What's NEEDED to measure distance from lands?

[BillPa]

Here's the method I've used ... http://forum.snipershide.com/snipers-hide-reloading/44357-hand-loading-long-range-3-finding-start-oal.html



Now take a good rubber band and loop it over the scope and onto the back of the bolt to hold it in a forward position. This insertion of the dummy round needs a gentle touch with both your hands, and in the holding of the bolt by the rubber band..

What dimension is included in the measurement doing it this way?
http://i62.tinypic.com/hv5g8j.jpg

Hint, it will add .060"-.070" to the measurement.

[foxx]

Gotta be the


I dont know.

[foxx]

Unless you remove it, the extractor.

[RevM]

What dimension is included in the measurement doing it this way?

Hint, it will add .060"-.070" to the measurement.

As long as you've removed the extractor and made sure the firing pin is not protruding ... ??? Nothing???

ETA: wrote my reply while foxx was posting!

[foxx]

I might have beat you to it by a half minute, but I am sure I had to think a lot harder and longer than you!

[JTCrl]

I've used the Hornady comparator for a few years and learned early that the hole does not match the barrel, as Foxx stated above. If it did you could measure one bullet and use that measurement to load all bullets. You can't. In my rifle the Berger 55gn HPFB measures 1.995, the Berger 73gn HPBT measures 2.055, and the Hornady 60 Vmax measures 1.920. It also takes a bit of practice to get consistent measurements so you can repeat the "sweet spot" for your rifle shooting a particular bullet/load combination.

When success depends on how many times you can hit a dot the size of a pimple 200 yards away the small stuff matters.

[BillPa]

As long as you've removed the extractor and made sure the firing pin is not protruding ... ??? Nothing???



Nope, the primary extraction which is usually in the .060"-.070" range, the difference between the bolt being locked to battery and unlocked - pushed fully forward. Since the "to the land" dimension is from a closed locked breach face to the point a bullet ogive contacts the lands the amount of PE would added to the measurement.

For example, if his measurement was 3.00" with a PE of .050" the actual TTLL would be 2.950". Whoops!!!!

Bill

[FW Conch]

3.00" - .050" = 2.950" I think ??? :-))

[BillPa]

3.00" - .050" = 2.950" I think ??? :-))

You thunked right! I forgotted the "9" when type'n. :p

Bill

[foxx]

"Ah... I see... " , said the blind man as he picked up his hammer and saw.
and there's no getting around that, either.

[scooterf79]

Apparently Ive caused quite the response with this thread lol. Seriously though I appreciate the responses. Ill probably end up getting the tools but, for trial purposes Ill end up trying the socket just to see how close my rounds are to each other.
Lots of good info here.
Question the modified cases hornady sells...what if they dont make them for your cartridge? Can u modify one of your own to work?
Scooter

[justdave]

Apparently Ive caused quite the response with this thread lol. Seriously though I appreciate the responses. Ill probably end up getting the tools but, for trial purposes Ill end up trying the socket just to see how close my rounds are to each other.
Lots of good info here.
Question the modified cases hornady sells...what if they dont make them for your cartridge? Can u modify one of your own to work?
Scooter

You can drill and tap one of your cases to fit the rod, 5/16-24 (double check that) and carefully expand the neck with the chuck end of drill bits until you get the right bullet fit. That's how I made modified Ackley cases anyway.

[mike21]

You can drill and tap one of your cases to fit the rod, 5/16-24 (double check that) and carefully expand the neck with the chuck end of drill bits until you get the right bullet fit. That's how I made modified Ackley cases anyway.

Agree with dave...except the tap size that worked for me is 5/16-36. I recall having difficulties finding it locally, so I just ordered it online. I also used a spent (fired) case from each rifle chamber thinking that might eliminate shoulder inaccuracies from new brass or the modified case you buy from Hornady.

Here's a link to a thread addressing the topic from last fall. As you can see, there are different ways to skin this cat.

http://www.savageshooters.com/showthread.php?30527-Bullet-Seating-Depth-Measuring-Problem-Touch-Jamb-or

Good luck with whichever method you choose.

[RevM]

Nope, the primary extraction which is usually in the .060"-.070" range, the difference between the bolt being locked to battery and unlocked - pushed fully forward. Since the "to the land" dimension is from a closed locked breach face to the point a bullet ogive contacts the lands the amount of PE would added to the measurement.

For example, if his measurement was 3.00" with a PE of .050" the actual TTLL would be 2.950". Whoops!!!!

Bill


I've been stewing over this ... I don't think this is the case.

To use this method you get a first position (the zero position) from the closed and locked bolt face to muzzle with your cleaning rod and the first of two rod stop lock rings. Then you place the too long dummy cartridge in the gun and find a second position and lock in your second rod stop ... in this process you are only holding the dummy round in place with the rubber bands to make sure the bullet is gently held against the lands. The distance between the rod stops is the maximum COAL for that particular bullet. The Primary Extraction doesn't come into play because you capture it when finding your zero off the closed bolt face.

[foxx]

I've been stewing over this ... I don't think this is the case.

To use this method you get a first position (the zero position) from the closed and locked bolt face to muzzle with your cleaning rod and the first of two rod stop lock rings. Then you place the too long dummy cartridge in the gun and find a second position and lock in your second rod stop ... in this process you are only holding the dummy round in place with the rubber bands to make sure the bullet is gently held against the lands. The distance between the rod stops is the maximum COAL for that particular bullet. The Primary Extraction doesn't come into play because you capture it when finding your zero off the closed bolt face.

But the pic shows the bolt is not closed. The handle is UP and the rubber band is gently holding it closed, but not as tightly as it would be if you lowered the bolt "into battery".

[RevM]

Exactly. That's the second measurement just to determine the distance from the bullet tip to the muzzle.

[foxx]

I am not following you, Rev. I think what Bill is saying with the Savage 10/110's, is the cart is not actually seated firmly into the chamber unless the bolt is lowered, even with the rubber bands drawing it in. Are you addressing that?

[RevM]

Yes. The only measurement where it matters if the bolt is closed is the zero measurement. The first measurement you take is finding the position of the first rod stop ... in that case the bolt is fully closed on an empty chamber and you are positioning the first rod stop with the cleaning rod against the bolt face (again, with the bolt closed ... they don't show a picture of that one because there is nothing special about it). You then open the action, put the far too long dummy round in the chamber and use the bolt with the rubber band merely to hold the bullet up against the lands without jamming it ... you then lock down the second rod stop with the rod touching the tip of the bullet and make your measurement.

Theoretically you could get the same second rod stop position by leaving the bolt wide open and having another person hold that dummy bullet against the lands with their finger ... the bolt has nothing to do with the second measurement. It IS important (and it must be closed and locked in place) for the first - or zero - position determination.

[scooterf79]

Thanks for all the input guys.
Mike and Dave, thanks! I actually have a 280AI and thats the main reason I was asking. Thanks for the link!
Scooter