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- Thread starter gunsdora
- Start date
- Location
- Western Manitoba
If you go to SAAMI.org site and look up centerfire rifle chamber drawings, the 8x57 shows min at 1.8743" and the max at 1.8843" for a .0100" difference. This measurement is from case head base (bolt face) to a theory datum point part way along shoulder. I cut circles from different thickness of blades from feeler gauge set, just smaller than the case head. With small dab of white grease, they will stick to bolt face. Try different thicknesses with the GO gauge. Assuming your GO gauge is perfectly SAAMI minimum, then you should not be able to close on a .010" shim. Keep trying with thinner shims if you want, but close on GO and doesn't close on GO+.010" puts your chamber within SAAMI tolerances for factory ammunition. No idea what original military specs were or how you would source those gauges. If you handload, you can adjust your sizing die to accommodate longer chambers (within reason - say up to .005" beyond NOGO) - but if you are beyond NOGO, do not expect factory ammunition to work reliably.
- Location
- Western Manitoba
I do not have 8x57 gauges on hand so I am going from what I found on Internet - appears that Forster GO gauge is 1.874", NOGO is 1.880" and FIELD is 1.8843". So, assuming that your GO gauge is a true SAAMI minimum, you are .005-.006 larger than GO, which is pretty much at NOGO. If you were installing a barrel, and if you have 75% or more bearing on both locking lugs, you would say you are good. There is still another .004" to go to FIELD length, so your set-up would not close on a FIELD gauge, again, assuming that your GO gauge is truly a perfect SAAMI minimum.
Many causes for backed out primers, but given your headspace measurements, I would be thinking you are shooting relatively mild loads - firing pin strike pushes case forward, brass is sealing and grabbing on chamber walls and the case head is not being pushed all the way back to bolt face, resulting in slight primer protrusion. You can prevent this by backing up your sizing die, then sizing fired cases one at a time, try in your chamber, turn in a bit more, etc. When you are close, the case will not chamber because squishing the circumference pushes the shoulder forward. Continuing to work down 1/8 turn at a time should get you to point where your sized brass just chambers snugly. No more protruding primers. The best gauge to use for setting your sizing die is your rifle's bolt and chamber. If you are loading for many rifle of same cartridge, follow the manufacturer's instructions for full length sizing and the cartridge will fit in any rifle that is in tolerance (and you may get protruding primers in some).
Many causes for backed out primers, but given your headspace measurements, I would be thinking you are shooting relatively mild loads - firing pin strike pushes case forward, brass is sealing and grabbing on chamber walls and the case head is not being pushed all the way back to bolt face, resulting in slight primer protrusion. You can prevent this by backing up your sizing die, then sizing fired cases one at a time, try in your chamber, turn in a bit more, etc. When you are close, the case will not chamber because squishing the circumference pushes the shoulder forward. Continuing to work down 1/8 turn at a time should get you to point where your sized brass just chambers snugly. No more protruding primers. The best gauge to use for setting your sizing die is your rifle's bolt and chamber. If you are loading for many rifle of same cartridge, follow the manufacturer's instructions for full length sizing and the cartridge will fit in any rifle that is in tolerance (and you may get protruding primers in some).
Gunsdora, if you're handloading for the rifle, why are you concerned?????
Once the case is fire formed, neck resize only and go from there.
The condition you're describing isn't at all uncommon when it comes to mixmasters. This doesn't make the rifle unsafe.
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Once the case is fire formed, neck resize only and go from there.
The condition you're describing isn't at all uncommon when it comes to mixmasters. This doesn't make the rifle unsafe.
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Gunsdora, if you're handloading for the rifle, why are you concerned?????
Once the case is fire formed, neck resize only and go from there.
The condition you're describing isn't at all uncommon when it comes to mixmasters. This doesn't make the rifle unsafe.
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Julian Hatcher has a very interesting paragraph about headspace in his book "Hatchers Notebook"
Julian Hatcher has a very interesting paragraph about headspace in his book "Hatchers Notebook"
I've read it. He was commenting on grossly over maximum headspace. Not so much because of catastrophic failure but because of primer issues with leakage burning rings in the bolt face and maybe allowing debris and gas to get into the shooters face.
From Gunsdora's description, a few thou isn't going to be an issue.
Have you ever blown out cartridges to match chambers for a wildcat or to fireform new brass to a custom rifle?? Over max headspace is usually extreme.
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- Location
- Western Manitoba
I have only used a neck sizing die on a 7x57. After a couple firings, the case was getting tight to chamber, so you end up having to full length size at some point, anyway. The issue is learning how to set the full length sizing die so you closely match your chamber length. That may or may not result in your shell holder against the bottom of the die bottom. You can full length size, just make sure your product fits snugly in your chamber, and your primer issue will go away.
Just to satisfy yourself, take one of your full length sized cartridges . Cut a little circle from printer paper (its about .004" thick) Or one thickness of scotch tape (its about .002" thick). Put it on your cartridge face. Chances are you will be able to chamber and close the bolt. That is showing you how much longer your chamber is, compared to the cartridge - or, how much too much you are pushing your cartridge shoulder back, by the way you have set your full length sizing die. Back it out an 1/8 turn and try another fired case until case just nicely chambers.
Again, as you insert a fired cartridge (that does chamber in your rifle) into a full length sizer, the first actions are the die is squeezing down the circumference of the body. That pushes the shoulder of the case forward in the die. If you do this 1/8 of a turn at a time, you will get to a point where your cartridge will no longer chamber in your rifle - the shoulder is now pushed forward from where it was when fired in you chamber. Keep advancing the die a bit at a turn and you will reach a setting where the case will just nicely chamber - now you have the body squeezed down a bit, and the case head to shoulder is basically the same as your bolt face to chamber shoulder. Case can not move forward on the firing pin strike, therefore primer can't protrude. Some guns have stretch - a friend had a Savage 99 that would protrude primers all the time, but Mausers with both locking lugs bearing will not have noticeable stretch.
Just to satisfy yourself, take one of your full length sized cartridges . Cut a little circle from printer paper (its about .004" thick) Or one thickness of scotch tape (its about .002" thick). Put it on your cartridge face. Chances are you will be able to chamber and close the bolt. That is showing you how much longer your chamber is, compared to the cartridge - or, how much too much you are pushing your cartridge shoulder back, by the way you have set your full length sizing die. Back it out an 1/8 turn and try another fired case until case just nicely chambers.
Again, as you insert a fired cartridge (that does chamber in your rifle) into a full length sizer, the first actions are the die is squeezing down the circumference of the body. That pushes the shoulder of the case forward in the die. If you do this 1/8 of a turn at a time, you will get to a point where your cartridge will no longer chamber in your rifle - the shoulder is now pushed forward from where it was when fired in you chamber. Keep advancing the die a bit at a turn and you will reach a setting where the case will just nicely chamber - now you have the body squeezed down a bit, and the case head to shoulder is basically the same as your bolt face to chamber shoulder. Case can not move forward on the firing pin strike, therefore primer can't protrude. Some guns have stretch - a friend had a Savage 99 that would protrude primers all the time, but Mausers with both locking lugs bearing will not have noticeable stretch.
- Location
- Western Manitoba
In Post #3 you said you reload with used brass. Sounds like you do not own either neck or full length die. Were the protruding primers on factory ammunition or on handholds that you had made up?
