Unusually Tight Chamber

I just finished putting together my first Savage build. It's chambered in .308. The action is a model 10 with a Shilen 1:10 twist. I have been shooting a .308 Mauser I built that had an Adams & Bennet barrel that was short chambered. I finished the chamber and head spaced it myself with the help of a fiend with a lathe. My COAL with a SMK 168 bullet touched the lands at 2.865 or so. I have had good luck jumping about .020 to the lands. I picked up some 155 gr. SMK's and tried to see how they fit my chamber in the Mauser. Wouldn't even touch the lands before they fell out of the case. I tried these same bullets in the Savage. They touched the lands at around 2.820. The 168 SMK's touched the lands with a COAL of 2.730! Anyone had the same experience with these Shilen or similar barrels? I'm so used to hearing about Remingtons that have a COAL of 2.90 and still not touch the lands. I would just like some feed back if this is unusual or not. I guess I won't be chasing the lands anytime soon!!!:confused:


Mark

Well, Thanks for all the input guys. This thread has been read by 90+ people and not a single reply...sigh. I just spent near a $1000 for good parts to put together a good shooting rifle, full length sized brass to fit this tight chamber and yet I can't seat a standard SMK 168 anywhere near the minimum OAL shown by any manual. I guess I'll have to try the guy I bought all this stuff from and see if he has a clue. I thought there would be one person that has dealt with Savages (this is a Savage forum, no?) that could give me a reasonable explanation as to why I can't chamber this bullet?

Sorry. I own over a dozen Savages, never had that problem. However, I also have never had that barrel.

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Originally Posted by PAPERKILLER

Well, Thanks for all the input guys. This thread has been read by 90+ people and not a single reply...sigh.

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Sorry, I just tuned back in.

I installed a factory 25-06 sporter barrel the other day. Two things I typically do, one make a chamber cast and two, check a few bullets on the land lengths.

Per the SAAMI cartridge print the overall cartridge length( case head to bullet tip) for the 25-06 is 3.010"-3,250". Here are the number I got for a few bullets.

Bullet - Comparator ogive length/COAL
100 Nosler BT.............. 2.691"/3.225"
100 Speer SP.............. 2.691"/3/172"
117 Sierra PH ............. 2.688"/3/146"
120 Nosler Solid base ... 2.693"/3.238"

As you can see all were under the maximum COAL of 3.250" in THAT chamber. It been my experience the freebore in Savage chambers tend to be close the middle of the spec.

Any help?

Bill

Het Bill,

Thanks for your input. It would seem there are some chambers that are shorter than SAAMi specs out there. In your case the heavies (120's) are .012 short. I could buy that the chamber is just a little short like that. But mine is 2.730 when SAAMI is 2.810! That's .080 short! The base of the bullet must be near or below the shoulder line, which might cause excessive pressure even on start load data. I'll call Shilen today and see if I can get any feed back from them. I do appreciate your feed back though.

Switch to a VLD bullet with a secant ogive. You will be able to seat out much further. The SMK's ogive starts pretty early compared to the VLD's. Your barrel does have a short throat for sure, you could send it back to Shilen, or you could also just have the throat reamed for whatever bullet you want. Being a 30 cal, most smiths will probably have the reamer.

I like tight chambers.

^^^^
who doesn't

it's not a tight chamber it is a short throat. There is a difference.

I wonder what reamer they used it sounds like it has tons of free bore. I wish my factory Savage 308 barrel had more.

I wonder if you are actually touching the lands or if it is just a tight throat like I have. Here is a thread I started in 2012:

http://www.savageshooters.com/showth...8-short-throat

Hey Jackpine,
Thanks for your link to your post about how tight your throat is on your Shilen barrel. I think this is exactly the problem I am/was having. I wanted to try some SMK 155 palmas anyway, so using a case with the slots cut in it to position a bullet into the throat? lands? I got a length of 2.810. So I decided to just load some up to 2.80 and shoot em. They worked fine. I now have the barrel broken in and the 155 palmas reach about 2.835/40 oal. I tried some hornady 168 hpbt which seem to have a longer point to ogive than the SMK's. I got a measurement of 2.828-32. So the throat has eroded enough to try those next. But the Sierra 168's are still short/tight at 2.765-70 so will just wait a while try those. How was your barrel for accuracy? Mine is shooting alright; around .75 MOA. I was hoping for something better. I have not done any load development yet, just finishing up a pound of Aliant PP2000mr. With the wild shortage of powder, I have had to be flexible about what I use to build loads with. I just try for a moderate load; for the 155's about 2700 fps. For the 168's I shoot for around 2600.

This rifle has been pretty frustrating for me. Probably around 1 MOA. I've only shot 175 SMKs through it. I'm going to try bedding the recoil lug this spring and if it doesn't improve I'll probably try a different barrel. But this is the first rifle I've put together and I'm fairly new at reloading so I guess I can't say for sure that the problem is the barrel.

Something else to consider: find a gunsmith or someone near you who has a borescope, and take a look at the area from the case mouth forward into the rifling. I've seen some barrels where the chamber was done in a hurry and wasn't actually concentric with the bore. In one case there was rifling all the way back to the case mouth on one side. That can/will severely screw with bullet seating, accuracy, etc.

Quote:

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Originally Posted by PAPERKILLER

I wanted to try some SMK 155 palmas anyway, so using a case with the slots cut in it to position a bullet into the throat? lands? I got a length of 2.810.

So I decided to just load some up to 2.80 and shoot em. They worked fine. I now have the barrel broken in and the 155 palmas reach about 2.835/40 oal.

But the Sierra 168's are still short/tight at 2.765-70

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I think your mixing apples and bumper bolts with the 2.7XX-2.8xx" measurements. Your confusing the overall loaded cartridge length, casehead to the bullet tip ( COAL ) and the casehhead to bullet ogive on the lands. One has little if any relationship to the other. The only time COAL is important is when a cartridge needs to function loading into and feeding from a magazine.

Its why in my earlier post I listed two number for different bullets, the "comparator" and COAL ( casehead to bullet tip) lengths. The comparator length is only a number used to measure where a particular bullet's ogive contacts the lands. I only need what length bullet "A" bullet and bullet "B" contact the lands.
http://i43.tinypic.com/f0zsrp.jpg



Bill

Thanks Bill for your explanation of how to use a comparator. I agree that it is the right tool for the job. I am just too cheap to spring for a new tool that doesn't give me a ton of more usable data. While it may be true that I am not taking a correct measurement from the ogive to case head, I still can't chamber that 168 SMK bullet without it being near/below the shoulder/neck junction. My home made bullet holder simply gives me basic data on where the bullet stops it's forward travel in MY neck/throat. The 168 SMK still jams into the throat/lands at 2.730 OAL. A better measuring stick doesn't change that fact. My set up tells me that a Hornady 168 hpbt do seem to have a longer point/ ogive, so they allow me to fit them in my case without jamming them into the lands. I made the rounds 2.810 and figured I still have .020 to the lands. I am a retired shooter on a budget and have to really weigh how useful and truly needed tools are before I purchase them. I would rather spend the money on more bullets or powder. I have been using Lake City Match brass from 1966! I have annealed, full sized and trimmed the flash hole. It cost me $30 for 140 pieces of brass. I shoot factory second bullets as it's hard for me to shoot $.30 bullets. I am cheap, cheap, cheap. I would love to have a better full length die or a bunch of Lapua brass as I know it is better brass and will give me some additional accuracy. I don't sort bullets or cases by weight yet, and I don't turn necks, yet. I seem to have run into a wall at about .75 MOA with the new Savage I put together. It has been really frustrating that the Savage doesn't shoot any better than the Mauser I have 3000 rounds thru and shoots near 3" at 300 yards. So, in short; I may be in the market for a comparator. Or some better quality brass. Or maybe a good digital scale.

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Originally Posted by PAPERKILLER

Thanks Bill for your explanation of how to use a comparator. I agree that it is the right tool for the job. I am just too cheap to spring for a new tool that doesn't give me a ton of more usable data.

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You're financially conservative, I'm cheap! :p

Actually you can do the same thing with a six or eight point socket, a caliper and a split neck case. The socket takes the place of my fancy bushing on the bullet ogive. Your only looking for a number regardless what it is. If it works out to 2.00" or 2.500" it doesn't matter. You only need to know where bullets "A" and "B" contact the lands and adjust the seating depths accordingly.

Bill

Thanks for the thought Bill. So your suggesting using a small socket that touches somewhere near the ogive of the bullet, then measure oal to the top of the socket. Good thought, I'll try it.

...I finished the chamber and head spaced it myself with the help of a fiend with a lathe...

Don't get help from fiends - they'll deliberately screw your chamber up.

(Sorry, couldn't help myself)

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Originally Posted by PAPERKILLER

Thanks for the thought Bill. So your suggesting using a small socket that touches somewhere near the ogive of the bullet, then measure oal to the top of the socket. Good thought, I'll try it.

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Yeah, you only need a length for various bullets on the lands. The numbers you come up with won't be to any kind of a "Spec", they'll only to tell you bullet "A" is on the lands at X length and bullet "B" at another. Why its called a "Comparator" length.

Bill

Yea, the guy with the lathe WAS a fiend...He figured out how to wrestle a barrel that had been in place for 70 years without bending or breaking anything. Then he was able to set up his 60 year old lathe and finish reaming the chamber with my directions I had read on the net. He did a great job thought, the headspace was within a thousandth when we dropped the bolt on the go gauge. I learned a lot on that rifle. After chambering the $150 Adams & Bennett stainless fluted barrel, I free floated the barrel and then bedded it. I got into reloading and was able to hold MOA to 300 yards after breaking in the evil rough barrel with some basic reloads. I really like to tinker with rifle building/ tuning. So that's how I started this Savage build. I thought at the time that half of the accuracy in a rifle was the quality of the barrel, so bought a Shilen match barrel and screwed it to a model 12 receiver. I picked up a nice long range target stock and bedded the recoil lug. It seems really hard to bed the rear action screw with the trigger configuration. There is a pillar bedded there, but it actually doesn't contact the action. There is a bracket for the magazine sandwiched between the pillar top and the action. The stock is inlet for the bracket and I don't think the action is actually contacting it. I think it is causing some vibration. I can just hold MOA with this rifle to 300 yards. I really wanted to shot out to 600 yards, but wha'ts the point if I'm shooting 8 or 10 inch "groups". I took the rifle apart today (had to tap the barreled action out with a rubber mallet as the recoil lug is that tight, didn't use tape on the front of the recoil lug). I had some pond liner material that is .040 thick and cut a small square washer to try to tighten up the rear action to pillar and stock.


BillPa, Thanks for the idea of using a 7mm socket for a comparator. I measured a bunch of bullets and was getting much more accurate reading from ogive to case head. I had noticed the vagerites of OAL from one round to another, up to 10 or 12 thous. (I am shooting seconds). But the comparator lengths are much more consistant.