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Thread: Factory Chamber vs. Criterion Chamber

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    Factory Chamber vs. Criterion Chamber

    As some of you know, I swapped my factory .308 barrel for a .308 Criterion on Friday. This afternoon, I spent a few hours resizing and prepping brass for load development. I'd saved about 70 pieces fired from my factory barrel, and shot 30 through the new barrel yesterday. While resizing, I noticed the brass from the factory barrel was very hard to full-length size (it was properly lubed), but the brass from the new barrel sized very easily. Is this likely caused by much closer tolerances on the Criterion barrel?

    Thanks!

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    Basic Member Robinhood's Avatar
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    I'm thinking about two things that make brass need more effort to size. Chamber dimensions and work hardening.
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    Quote Originally Posted by JoeJoe View Post
    As some of you know, I swapped my factory .308 barrel for a .308 Criterion on Friday. This afternoon, I spent a few hours resizing and prepping brass for load development. I'd saved about 70 pieces fired from my factory barrel, and shot 30 through the new barrel yesterday. While resizing, I noticed the brass from the factory barrel was very hard to full-length size (it was properly lubed), but the brass from the new barrel sized very easily. Is this likely caused by much closer tolerances on the Criterion barrel?

    Thanks!
    I would agree with robinhood... either tighter chamber on criterion ( all my criterion and shilen barrel brass resized easier) and just maybe needs annealed

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    Maybe and maybe not. Manufacturers of firearms can use a SAAMI min spec and or what is called a production chamber. Production chambers tend to be looser/bigger on sizes/tolerances.

    That being said headspace dimension from one barrel to the next and or to the same firearm can vary. This can make a difference.

    Also the same load run thru one barrel can react different in another barrel. Why? One is the chamber and also another are the actual bore and groove sizes can vary from barrel to barrel. A tighter bore/groove and or a tighter chamber can drive up pressures and or drop pressures. This has an effect on the brass/ammo etc...

    Custom barrel makers can and do use SAAMI min spec. Or theyíre own specíd chambers/reamers made to theyíre own design.

    The best thing to do would be to call Criterion and ask them if they can supply you with a copy of the chamber reamer print that they used. If we get asked I know by looking at the customers order what reamer we used.

    Also keep in mind that over time as a reamer is used it can cut differently or should I say very slightly to a different size. A good example....a reamer that cuts even a .0001Ē (either intentionally or not) under on the throat size and you get a different lot of bullets and or ammo can drive up the pressures easily 4K to 6K psi. Thatís data I recently was involved with ammunition test barrels and chamber sizes in the throat and what it can do.

    Keep in mind and Iíll say it again....even when the same reamer is used, headspace is theoretically set the same....a tighter or looser bore can effect pressures and have different effects on the brass.

    Yes brass work hardens over time not to mention different lots. Same as bullets....different lots of jackets as well as I do believe as the jackets are made they can work harden as well.

    We all deal with a lot of variables.

    It wouldnít hurt to call Criterion and ask if you can get a copy of the reamer print that was used in the barrel.

    Later, Frank
    Bartlein Barrels

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    I/we get asked a question pretty frequently. Do we have a match chamber/reamer? I have to ask the question back right away. Define match chamber? What do you want?

    Shorter/tighter throat/freebore?
    No turn neck?
    Tight neck?
    Tight case body?
    Or a combination of all of the above or some of the above?

    Sometimes before I even get a reply I will say right away....what are you using the gun for? Then go from there.

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    Quote Originally Posted by Shortbox4x4 View Post
    Maybe and maybe not. Manufacturers of firearms can use a SAAMI min spec and or what is called a production chamber. Production chambers tend to be looser/bigger on sizes/tolerances.

    That being said headspace dimension from one barrel to the next and or to the same firearm can vary. This can make a difference.

    Also the same load run thru one barrel can react different in another barrel. Why? One is the chamber and also another are the actual bore and groove sizes can vary from barrel to barrel. A tighter bore/groove and or a tighter chamber can drive up pressures and or drop pressures. This has an effect on the brass/ammo etc...

    Custom barrel makers can and do use SAAMI min spec. Or theyíre own specíd chambers/reamers made to theyíre own design.

    The best thing to do would be to call Criterion and ask them if they can supply you with a copy of the chamber reamer print that they used. If we get asked I know by looking at the customers order what reamer we used.

    Also keep in mind that over time as a reamer is used it can cut differently or should I say very slightly to a different size. A good example....a reamer that cuts even a .0001Ē (either intentionally or not) under on the throat size and you get a different lot of bullets and or ammo can drive up the pressures easily 4K to 6K psi. Thatís data I recently was involved with ammunition test barrels and chamber sizes in the throat and what it can do.

    Keep in mind and Iíll say it again....even when the same reamer is used, headspace is theoretically set the same....a tighter or looser bore can effect pressures and have different effects on the brass.

    Yes brass work hardens over time not to mention different lots. Same as bullets....different lots of jackets as well as I do believe as the jackets are made they can work harden as well.

    We all deal with a lot of variables.

    It wouldnít hurt to call Criterion and ask if you can get a copy of the reamer print that was used in the barrel.

    Later, Frank
    Bartlein Barrels
    I definitely cannot argue against anything you said but criterion and shilen cut their chamber tighter than most production rifles. I've seen it time and time again on just how much tougher it is getting a go gauge into their chambers, I'm sure there is still variances but I can say from 1st hand experienced time and time again I'm always amazed out tight the chambers are on shilens and criterions, shilens even more so.. for example I can take any shilen s/s bare for AR or bolt and it takes a tad bit of force to go into battery, criterion is the same way but not as tight. Most factory rifles I have no resistance getting a go gauge into full battery but definitely your advice is solid

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    Thanks all.....one other observation I made, which makes me think the Criterion is a bit tighter, is the fired brass from my factory barrel would not fit into the Criterion.....before installing the new barrel, I dropped a factory shell into the chamber and it dropped right in.....doing the same thing with a once fired brass resulted in the last 1/2" or so of the brass sticking out (I was too chicken to shove it in there and see exactly how tight). Since the pressures are great enough to conform the brass to the chamber, made sense to me the factory chamber was a tad "loose".

    I appreciate all the insight!

    Joe

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    Quote Originally Posted by Ted_Feasel View Post
    I definitely cannot argue against anything you said but criterion and shilen cut their chamber tighter than most production rifles. I've seen it time and time again on just how much tougher it is getting a go gauge into their chambers, I'm sure there is still variances but I can say from 1st hand experienced time and time again I'm always amazed out tight the chambers are on shilens and criterions, shilens even more so.. for example I can take any shilen s/s bare for AR or bolt and it takes a tad bit of force to go into battery, criterion is the same way but not as tight. Most factory rifles I have no resistance getting a go gauge into full battery but definitely your advice is solid

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    The go or no go gage only measures from the bolt face to the datum line of the shoulder. It does not measure diameters.

    If the go gage is being difficult to install because of diameters possibly being to tight then I would question that.

    If the go gage goes in and stops at basically 0 headspace. Thatís different from being tight on the diameter. Tight on the diameter can cause problems.

    Look at a reamer print per say for 308win. Or 6BR etc...guys try and tighten up the diameter of the chamber at the .200Ē dimension from the case head. When you do this you can end up getting that tight bolt opening/double click per say. Guys think at times the loads are too hot but they made the chamber to tight on that diameter.

    Thatís why I say ask for a copy of the reamer print from the gunsmith or barrel maker that did the chamber work/install. Thatís the only way your going to know technically what reamer was used and to what spec the reamer was ground/made to. Otherwise itís a guess.

    To an extent we donít want a loose sloppy chamber but too tight causes problems as well. There has to be a balance.

    One ammo maker about a year ago wanted to order special 30cal ammunition test barrels for a special run of ammo for some target shooters. I wonít give out the exact caliber. So when they called to place the order I gave them theyíre options as to the reamer specís and bore specs of the most popular being used for that type of match shooting. They had no clue what was even being used to begin with. It took data from myself and another party and about 6 months for them to make a decision. I didnít want to just make what they originally asked for as it couldíve caused some very serious over pressures and after they looked at the data that was given to them they understood why and helped them make a better decision.

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    There's a 50/50 chance anytime you full-length resize with brass fired in a different rifle it will be more difficult to full-length resize in the newer rifle . . . if you are using the same dies. Different rifle makes have different chamber dimensions. Could be tighter chamber, could be shorter shoulder/headspace, etc.
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    Quote Originally Posted by Shortbox4x4 View Post
    The go or no go gage only measures from the bolt face to the datum line of the shoulder. It does not measure diameters.

    If the go gage is being difficult to install because of diameters possibly being to tight then I would question that.

    If the go gage goes in and stops at basically 0 headspace. Thatís different from being tight on the diameter. Tight on the diameter can cause problems.

    Look at a reamer print per say for 308win. Or 6BR etc...guys try and tighten up the diameter of the chamber at the .200Ē dimension from the case head. When you do this you can end up getting that tight bolt opening/double click per say. Guys think at times the loads are too hot but they made the chamber to tight on that diameter.

    Thatís why I say ask for a copy of the reamer print from the gunsmith or barrel maker that did the chamber work/install. Thatís the only way your going to know technically what reamer was used and to what spec the reamer was ground/made to. Otherwise itís a guess.

    To an extent we donít want a loose sloppy chamber but too tight causes problems as well. There has to be a balance.

    One ammo maker about a year ago wanted to order special 30cal ammunition test barrels for a special run of ammo for some target shooters. I wonít give out the exact caliber. So when they called to place the order I gave them theyíre options as to the reamer specís and bore specs of the most popular being used for that type of match shooting. They had no clue what was even being used to begin with. It took data from myself and another party and about 6 months for them to make a decision. I didnít want to just make what they originally asked for as it couldíve caused some very serious over pressures and after they looked at the data that was given to them they understood why and helped them make a better decision.
    The go gauge is tight from chamber diameters, I've measured the many times.. if it was headspace or would not go into battery at at all as clymer gauges as most I reckon dont flex.. I've actually taken ball gauges and compared them to caliper measurements and the chamber is just tighter.. its typical of match grade chambers, the hold it all to exact(or close as possible to coaxial center ) as possible.. believe me I'm by no means new to building championship grade rifles.. I'm just low key about it till now, I'm finally equipped to to do all my own machine work including bore and chamber. I have over 40 years time in learning gunsmithing and precision machining in general thank to my late great master machinist daddy

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    Quote Originally Posted by Shortbox4x4 View Post
    The go or no go gage only measures from the bolt face to the datum line of the shoulder. It does not measure diameters.

    If the go gage is being difficult to install because of diameters possibly being to tight then I would question that.

    If the go gage goes in and stops at basically 0 headspace. Thatís different from being tight on the diameter. Tight on the diameter can cause problems.

    Look at a reamer print per say for 308win. Or 6BR etc...guys try and tighten up the diameter of the chamber at the .200Ē dimension from the case head. When you do this you can end up getting that tight bolt opening/double click per say. Guys think at times the loads are too hot but they made the chamber to tight on that diameter.

    Thatís why I say ask for a copy of the reamer print from the gunsmith or barrel maker that did the chamber work/install. Thatís the only way your going to know technically what reamer was used and to what spec the reamer was ground/made to. Otherwise itís a guess.

    To an extent we donít want a loose sloppy chamber but too tight causes problems as well. There has to be a balance.

    One ammo maker about a year ago wanted to order special 30cal ammunition test barrels for a special run of ammo for some target shooters. I wonít give out the exact caliber. So when they called to place the order I gave them theyíre options as to the reamer specís and bore specs of the most popular being used for that type of match shooting. They had no clue what was even being used to begin with. It took data from myself and another party and about 6 months for them to make a decision. I didnít want to just make what they originally asked for as it couldíve caused some very serious over pressures and after they looked at the data that was given to them they understood why and helped them make a better decision.
    ^This.

    Example:
    Iíve got an Obermeyer spec 7-08 reamer built by the NW tool maker that starts with a P. Itís too tight. The first chamber I reamed with it I thought I had a primary extraction issue. My chambers usually get bigger not smaller....lol. So I reamed another one. Same. So I tried another action. Same again. After a conversation with a custom action maker in PA that Iím a loyal customer to, I sent the reamer to Dave Manson to have him check out with his optical comparator. Long story short he was unable to fix it due to dimensional issues. I was able to polish one of them out just enough that I donít have to use a small base die every time as I did before. The other I havenít messed with as I still get grumpy about it. The reamer is a nice sharp little paper weight now.

    Anyway, through all, the go gauge was never tight. If a go gauge is tight in diameter, Iíd say there is something wrong with the gauge or the hole itís going into. I doubt Shilen or Criterion sends out undersized chambers as a standard practice. Minimum spec....sure.

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    Quote Originally Posted by gbflyer View Post
    ^This.

    Example:
    Iíve got an Obermeyer spec 7-08 reamer built by the NW tool maker that starts with a P. Itís too tight. The first chamber I reamed with it I thought I had a primary extraction issue. My chambers usually get bigger not smaller....lol. So I reamed another one. Same. So I tried another action. Same again. After a conversation with a custom action maker in PA that Iím a loyal customer to, I sent the reamer to Dave Manson to have him check out with his optical comparator. Long story short he was unable to fix it due to dimensional issues. I was able to polish one of them out just enough that I donít have to use a small base die every time as I did before. The other I havenít messed with as I still get grumpy about it. The reamer is a nice sharp little paper weight now.

    Anyway, through all, the go gauge was never tight. If a go gauge is tight in diameter, Iíd say there is something wrong with the gauge or the hole itís going into. I doubt Shilen or Criterion sends out undersized chambers as a standard practice. Minimum spec....sure.
    I agree with what you are saying.. just been my experience that match chamber are.to the minimum if not a little less

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    Ted, I like you bringing up about working with the older generation of machinist and what they bring to the table. What is being taught in schools now a days doesn’t even compare to what they taught in the past and the tooling/machining knowledge is being lost in my opinion.

    A new rifle manufacturer is asking us and a button barrel maker to supply them with for the most part finished barrels. They want to offer both types. The chamber spec is a SAAMI min spec chamber. The headspace tolerance on the print is -.001” to +.001”. Which is a total of .002”. Even if you would check a barrel from the same maker and theoretically speaking the very same reamer was used and now throw in receiver and bolt tolerances it would possibly appear that one chamber is tighter than the other but it might not necessarily be the case. They might also be spec the headspace that way so when they go to put the barrel onto the receiver if the headspace is too tight they can go in with they’re reamer/tool and touch the chamber up and set the headspace. Which in our case we have no control over what reamer/tool they are using and by adding another tool and set up to the mix how it cuts and what the final dimensions end up being.

    Between the receiver and bolt and barrel tolerances at times you are stacking the dimensions. Sometimes this works and sometimes it works against you. Even on custom actions or lets call it guns I’ve seen plenty of instances where they say that the firearm will accept a drop in barrel made to a given spec and it doesn’t. That’s why I say the best fit is still when you fit the barrel to the action on a individual bases.

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    Quote Originally Posted by Shortbox4x4 View Post
    Ted, I like you bringing up about working with the older generation of machinist and what they bring to the table. What is being taught in schools now a days doesnít even compare to what they taught in the past and the tooling/machining knowledge is being lost in my opinion.

    A new rifle manufacturer is asking us and a button barrel maker to supply them with for the most part finished barrels. They want to offer both types. The chamber spec is a SAAMI min spec chamber. The headspace tolerance on the print is -.001Ē to +.001Ē. Which is a total of .002Ē. Even if you would check a barrel from the same maker and theoretically speaking the very same reamer was used and now throw in receiver and bolt tolerances it would possibly appear that one chamber is tighter than the other but it might not necessarily be the case. They might also be spec the headspace that way so when they go to put the barrel onto the receiver if the headspace is too tight they can go in with theyíre reamer/tool and touch the chamber up and set the headspace. Which in our case we have no control over what reamer/tool they are using and by adding another tool and set up to the mix how it cuts and what the final dimensions end up being.

    Between the receiver and bolt and barrel tolerances at times you are stacking the dimensions. Sometimes this works and sometimes it works against you. Even on custom actions or lets call it guns Iíve seen plenty of instances where they say that the firearm will accept a drop in barrel made to a given spec and it doesnít. Thatís why I say the best fit is still when you fit the barrel to the action on a individual bases.
    I definitely agree having a barrel customer fit to a specific action can have its advantages. So far I can do everything needed except barrel work.. that will be one of my next big investments. I have thr blessing of having a very old gunsmith teaching me all he knows.

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    Thanks for bringing this up as it brings back some fond memories. I wish I could have learned everything my father-in-law knew about machine work. He was trained at Brown and Sharpe in the 50's and worked for Bendix. Later worked for Shakespeare then went in the Navy. He was playing with barrel rifling and planned on building a Sharps from scratch before he passed away.

    I love the folks on this forum. A great wealth of information to be had.

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    Quote Originally Posted by charlie b View Post
    Thanks for bringing this up as it brings back some fond memories. I wish I could have learned everything my father-in-law knew about machine work. He was trained at Brown and Sharpe in the 50's and worked for Bendix. Later worked for Shakespeare then went in the Navy. He was playing with barrel rifling and planned on building a Sharps from scratch before he passed away.

    I love the folks on this forum. A great wealth of information to be had.
    It really does bring me good memories. My daddy was a master at machining , he was one of those people if he needed a tool, he would just make it. He thought me alot and got me into gunsmithing, he was my range buddy also, when he passed last year alot of wisdom and knowledge were lost but I absorbed alot from him. I dont have a range buddy anymore either.

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    Sorry for your loss but envious at the same time. My father died of cancer when I was very young.

    I have never seen a chamber gauge that was very close to touching the bore. What brand of gauges did you use when you had one stuck in the chamber ID?
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    Quote Originally Posted by Ted_Feasel View Post
    I definitely cannot argue against anything you said but criterion and shilen cut their chamber tighter than most production rifles. I've seen it time and time again on just how much tougher it is getting a go gauge into their chambers,
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    Apples and Oranges.
    A chamber is cut to the dimensions of the reamer. Assuming the manufacturer cuts the entire chamber with a single reamer, it's a form tool and will be ground to SAAMI (or CIP ) specs for a factory barrel. This is because it's critical that factory barrels, be able to shoot all factory ammo, within the specified tolerances.

    Headspace on a Savage is controlled by how far you screw the barrel into the receiver, the chambers are cut so that there's specified case/go-gauge protrusion of around .125.
    Nothing to do with the reamer. Want light resistance with bolt close on a factory barrel? Re-set to zero headspace.

    Like Frank said, custom reamers may have tighter necks, longer freebore, and other slight modifications. Criterion does offer non-SAAMI chambers (such as "Match" which usually means more freebore), but again- different than a "tight" chamber.

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    Thanks tobnpr for the nice comment!

    Also guys just because a reamer is ground to a given spec doesn’t mean it will cut to spec!!!!!

    Like gbflyer had the problem with the 7-08Obermeyer reamer. We had to grab a new reamer for 50bmg for doing a batch of ammunition pressure test barrels. We have to measure the chambers in 10 different areas with ball gages and have to depth mic to the ball gage. We are given tolerances we have to hold for each individual gage.

    The reamer was cutting big on five of the different gages. I sent the reamer back to the manufacturer for them to inspect it. They told me it was in spec. I said it might be in spec but it’s not cutting to spec. So I sent one of the barrels with the inspection report along with the gages. I told them to measure the chamber and tell me what they get. All I got back was the reamer was in spec! I said I was done. Send my tooling back. We scrapped almost $5k worth of barrels. I refuse to buy anything from that maker anymore. Any of they’re tools come into our shop for like a customer fitting etc....we take the tool and will run it into a piece of scrap barrel etc...and we will see how it cuts for finish and size as well as how it cuts before we run it into a good/finished barrel.

    Later, Frank
    Bartlein Barrels

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    Quote Originally Posted by Shortbox4x4 View Post
    I sent the reamer back to the manufacturer for them to inspect it. They told me it was in spec. I said it might be in spec but itís not cutting to spec. So I sent one of the barrels with the inspection report along with the gages. I told them to measure the chamber and tell me what they get. All I got back was the reamer was in spec! I said I was done. Send my tooling back. We scrapped almost $5k worth of barrels. I refuse to buy anything from that maker anymore. Any of theyíre tools come into our shop for like a customer fitting etc....we take the tool and will run it into a piece of scrap barrel etc...and we will see how it cuts for finish and size as well as how it cuts before we run it into a good/finished barrel.

    Later, Frank
    Bartlein Barrels

    Just a guess from the clues above....reamer manufacturer starts with a "P"?

    Similar horror story was related recently by Chad Dixon. Scary...

    I'm amazed at the prices I see used reamers selling for on Fleabay. Even with a seller that says something like "got this in a lot, don't know anything about them", people actually pay money for them.

    I wouldn't want if for free. Well, maybe free...but I wouldn't touch it until I'd sent it to Manson to be checked and re-ground (assuming it could even be done).

    IMO, the barrel is THE most important part of the many variables that are needed for precision accuracy. Number 2, is the chamber.
    Without highly specialized equipment (that none of us have), we can't measure the geometry of any reamer. We need to rely on the reputation of the manufacturer- just like barrels.
    We can't air gauge them- which is why we rely on the top dogs like Bartlein.

    Interesting story, Frank. Thanks for passing it along.

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    Quote Originally Posted by tobnpr View Post
    Just a guess from the clues above....reamer manufacturer starts with a "P"?

    Similar horror story was related recently by Chad Dixon. Scary...

    I'm amazed at the prices I see used reamers selling for on Fleabay. Even with a seller that says something like "got this in a lot, don't know anything about them", people actually pay money for them.

    I wouldn't want if for free. Well, maybe free...but I wouldn't touch it until I'd sent it to Manson to be checked and re-ground (assuming it could even be done).

    IMO, the barrel is THE most important part of the many variables that are needed for precision accuracy. Number 2, is the chamber.
    Without highly specialized equipment (that none of us have), we can't measure the geometry of any reamer. We need to rely on the reputation of the manufacturer- just like barrels.
    We can't air gauge them- which is why we rely on the top dogs like Bartlein.

    Interesting story, Frank. Thanks for passing it along.
    I've always used clymer reamers and clymer hs gauges, never had problems, I've had a few custom touches and always bought clymer for my smith to use. I hope soon to start doing my own reaming.. I've got the mechanics and technical skills to do it just not equipment ... YET:)

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    Quote Originally Posted by tobnpr View Post
    Just a guess from the clues above....reamer manufacturer starts with a "P"?

    Similar horror story was related recently by Chad Dixon. Scary...

    I'm amazed at the prices I see used reamers selling for on Fleabay. Even with a seller that says something like "got this in a lot, don't know anything about them", people actually pay money for them.

    I wouldn't want if for free. Well, maybe free...but I wouldn't touch it until I'd sent it to Manson to be checked and re-ground (assuming it could even be done).

    IMO, the barrel is THE most important part of the many variables that are needed for precision accuracy. Number 2, is the chamber.
    Without highly specialized equipment (that none of us have), we can't measure the geometry of any reamer. We need to rely on the reputation of the manufacturer- just like barrels.
    We can't air gauge them- which is why we rely on the top dogs like Bartlein.

    Interesting story, Frank. Thanks for passing it along.
    Hahahaha. Iím one of those suckers that showed my ignorance on a used EBay reamer...300 H&H...new of course. Wonít cut hot butter. I still have it, keep it around as a reminder to never do it again.

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    Quote Originally Posted by tobnpr View Post
    Just a guess from the clues above....reamer manufacturer starts with a "P"?

    Similar horror story was related recently by Chad Dixon. Scary...

    I'm amazed at the prices I see used reamers selling for on Fleabay. Even with a seller that says something like "got this in a lot, don't know anything about them", people actually pay money for them.

    I wouldn't want if for free. Well, maybe free...but I wouldn't touch it until I'd sent it to Manson to be checked and re-ground (assuming it could even be done).

    IMO, the barrel is THE most important part of the many variables that are needed for precision accuracy. Number 2, is the chamber.
    Without highly specialized equipment (that none of us have), we can't measure the geometry of any reamer. We need to rely on the reputation of the manufacturer- just like barrels.
    We can't air gauge them- which is why we rely on the top dogs like Bartlein.

    Interesting story, Frank. Thanks for passing it along.
    Yes and like reamers/tools on Ebay there are places that will rent reamers. We once in a while get a customer saying, ďOh Iíll rent the reamer and send it to you for the build.Ē I say we wonít use the rental tools either. There is no history on them. How many times theyíve been used? The last time itís been resharpened etc...The only way we would use the tool is if the customer or the rental shop guaranteed us that if it scraps the barrel someone is paying for the barrel. Otherwise we end up eating it.

    Weíve had brand new reamers where they wouldnít even cut supplied to us by customers and or directly from the reamer maker and where we ordered the tool. We had a customer send in his complete rifle to us (we requested the whole thing be sent to us) because it wouldnít shoot. Barrel had 200 rounds on it in 6.5x284. I couldnít warranty the barrel. Interesting part was he had his own reamer. Not knowing how the gunsmith did the work etc...the reamer tore the shoulder of the chamber and tore the throat of the bore of the barrel as well. There was no saving it. There was so much build up on the chamber reamer that it was clearly caused by the tool and or the gunsmith wasnít using enough coolant/cutting oil or was pushing it to hard. I made a offer to the customer to help him out and asked if he wanted us to ship the rifle back to the smith. He said no. This was the second rifle the guy built and he had problems with the first one as well. He asked us to do all the work to fix it. This was just like 3 months ago.

    Going back to reamers not cutting to size and you think you have a match chamber because it feels tight....you cannot go by feel. We had a reamer we used for several test barrels in 30cal (Iím with holding actual chamber spec as itís not important). Shipped them all out at one time. Presto get a phone call from one of the ammo makers. They had some ammo that wouldnít chamber and some that would. That didnít make any sense. Told them to ship both barrels back to us. They also sent some samples of ammunition as well as some reference ammo. (Reference ammo is used for calibrating equipment and confirming things with the test barrels. The general public has no access to reference ammo). Sure enough during inspection some ammo chambered and some didnít. So I pulled all the technical drawings and started measuring everything. The reference ammo (would like to meet the rocket scientist that wrote the spec.) made the ammo have a max allowable dimension on the bullets to be .3090Ē (again doesnít make sense in a standard .308 caliber barrel) and wrote the spec.of the freebore diameter of the throat of the chamber to be .3090Ē diameter as well. Guess what reamer cut to .3088Ē/.3089Ē. This tighter .0001/.0002Ē undersize drove up pressures 4K to 6kpsi. The freebore is like .187Ē long and straight. So I used our bore gages to measure the throat area. We took the reamer print and the reamer to a shop that does with us and vice versa and is only 10 minutes away. They have a clean room and two CMM machines (basically $100k+ measuring equipment). They measured the reamer for us and guess what. What they measured vs our bore gages where identical. So I called the other two ammo/bullet makers that we made the same caliber barrels for at the same time. One place said yes this has been a problem. The other place thru them in the test fixtures and confirmed the same pressure problem and same chambering problem. So they went to the industry and are rewriting the tolerances spec for that particular caliber.

    You never want say any caliber where the throat is size on size with bullet diameters. Your just asking for problems. From pressure, to accuracy to feeding and reliability issues. I called the reamer maker and ordered another brand new reamer. Ran it into the barrels and sure enough it just barely cut/cleaned up the throat. All pressures dropped to normal spec and no more ammo being tight in the chambers. That .0001Ē tightness in the throat would stop the rounds from chambering (not forcing) by the rim thickness of the cartridge sticking out of the chamber.

  24. #24
    Team Savage
    Join Date
    Dec 2018
    Posts
    145
    Quote Originally Posted by gbflyer View Post
    Hahahaha. I’m one of those suckers that showed my ignorance on a used EBay reamer...300 H&H...new of course. Won’t cut hot butter. I still have it, keep it around as a reminder to never do it again.
    Unless the tool is completely junk...you can send it to places like JGS and they can resharpen it. If it’s a solid pilot reamer have them to convert it to a removable pilot/bushing type. I want to say to convert it to a bushing it’s like $35 for that.

  25. #25
    Basic Member
    Join Date
    Jan 2015
    Posts
    399
    Quote Originally Posted by Shortbox4x4 View Post
    Yes and like reamers/tools on Ebay there are places that will rent reamers. We once in a while get a customer saying, ďOh Iíll rent the reamer and send it to you for the build.Ē I say we wonít use the rental tools either. There is no history on them. How many times theyíve been used? The last time itís been resharpened etc...The only way we would use the tool is if the customer or the rental shop guaranteed us that if it scraps the barrel someone is paying for the barrel. Otherwise we end up eating it.

    Weíve had brand new reamers where they wouldnít even cut supplied to us by customers and or directly from the reamer maker and where we ordered the tool. We had a customer send in his complete rifle to us (we requested the whole thing be sent to us) because it wouldnít shoot. Barrel had 200 rounds on it in 6.5x284. I couldnít warranty the barrel. Interesting part was he had his own reamer. Not knowing how the gunsmith did the work etc...the reamer tore the shoulder of the chamber and tore the throat of the bore of the barrel as well. There was no saving it. There was so much build up on the chamber reamer that it was clearly caused by the tool and or the gunsmith wasnít using enough coolant/cutting oil or was pushing it to hard. I made a offer to the customer to help him out and asked if he wanted us to ship the rifle back to the smith. He said no. This was the second rifle the guy built and he had problems with the first one as well. He asked us to do all the work to fix it. This was just like 3 months ago.

    Going back to reamers not cutting to size and you think you have a match chamber because it feels tight....you cannot go by feel. We had a reamer we used for several test barrels in 30cal (Iím with holding actual chamber spec as itís not important). Shipped them all out at one time. Presto get a phone call from one of the ammo makers. They had some ammo that wouldnít chamber and some that would. That didnít make any sense. Told them to ship both barrels back to us. They also sent some samples of ammunition as well as some reference ammo. (Reference ammo is used for calibrating equipment and confirming things with the test barrels. The general public has no access to reference ammo). Sure enough during inspection some ammo chambered and some didnít. So I pulled all the technical drawings and started measuring everything. The reference ammo (would like to meet the rocket scientist that wrote the spec.) made the ammo have a max allowable dimension on the bullets to be .3090Ē (again doesnít make sense in a standard .308 caliber barrel) and wrote the spec.of the freebore diameter of the throat of the chamber to be .3090Ē diameter as well. Guess what reamer cut to .3088Ē/.3089Ē. This tighter .0001/.0002Ē undersize drove up pressures 4K to 6kpsi. The freebore is like .187Ē long and straight. So I used our bore gages to measure the throat area. We took the reamer print and the reamer to a shop that does with us and vice versa and is only 10 minutes away. They have a clean room and two CMM machines (basically $100k+ measuring equipment). They measured the reamer for us and guess what. What they measured vs our bore gages where identical. So I called the other two ammo/bullet makers that we made the same caliber barrels for at the same time. One place said yes this has been a problem. The other place thru them in the test fixtures and confirmed the same pressure problem and same chambering problem. So they went to the industry and are rewriting the tolerances spec for that particular caliber.

    You never want say any caliber where the throat is size on size with bullet diameters. Your just asking for problems. From pressure, to accuracy to feeding and reliability issues. I called the reamer maker and ordered another brand new reamer. Ran it into the barrels and sure enough it just barely cut/cleaned up the throat. All pressures dropped to normal spec and no more ammo being tight in the chambers. That .0001Ē tightness in the throat would stop the rounds from chambering (not forcing) by the rim thickness of the cartridge sticking out of the chamber.
    Really appreciate your knowledge sharing. Not a lot of pros are into it. Thank you.

    I have had decent luck with 4D Rentals but Iím not doing customer work, just for my own stuff. Winter in the part of Alaska that I live in is wet and dark, working in my shop/buying a couple barrels a year is cheaper than alcohol and reefer. . But yeah Iíve rented 5 from him so far, the only one that I had an issue with was a revolver cylinder reamer. I would not rent reamers if I was a professional though, for sure. If I have to eat a barrel, Iím the upset customer. Haha.

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