The load is as follows;
30-06 Sprg.
130 grain Hornady SP
55 grains AA Magnum Rifle Powder
Winchester Standard Primers
Rifle: Sporterized 1903A3

Question: Is .011 inch a safe amount for the primer to back out?
Note: The primer is flattened, "slightly"!

Thanks in advance; Chuck

Hey Chuck,

Be very, very careful. Anytime a primer backs out you should want to find out why.

Were the primers seated properly?

Is the powder temperature sensitive?

Are the bullets seated out too far?

Is the powder/primer combination too hot for the way your rifle is set up?

You should discuss these issues with your gunsmith and allow your gunsmith to check out your rifle.

You can never be too careful. Remember, the thing with fatal mistakes is that you only get one.

Good Shooting,

Smoker*

When you say the primer is lifting up from being seated .011(or whatever), does that mean its protruding that much above the head of the cartridge or is it lifting up even with the head of the cartridge? If its protruding above "even with the head of the cartridge", you have a bit of a head space problem and a under powered load. Or MRP is too slow for the application for which you are using it. To begin with, I would go to a heavier bullet or a faster powder. If you stick to the 130's, 4895 or 4064 comes to mind. If you switch to 165 or 180gr bullets, 4350 et al, comes to mind. After you have fired the rounds using full house loadings, adjust your resizing die so that it does not set the shoulders back when you resize. That should take care of your headspace problem. If you repeatedly stretch the case out and then set it back again, you will end up with a head seperation. But if you fire form the brass to your chamber with the first firing, you should not have a problem.
If the primer is merely coming back "even with the head of the cartridge", that's normal and don't worry about it.

The distance (.011)is the primer backing part way out of the primer pocket! Not flush with the case head!

Outside air temperature was around 65 degrees!

I pretty much figured this would happen! Accurate Arms MRP powder is "slow" and you are to use IMR-4831 or H-4831 loading data!

I want to use "light" loads, so I guess I need to use a faster powder!

Thanks Guys; Chuck

The primer backing out is caused by excessive headspace or oversizing your brass. Have experienced the same problem. Solution: start with a mild load (for safety) but set the bullet firmly into the lands. I use about .010. This keeps the case back against the bolt face when firing. If this does not entirely cure the problem increase the load while maintaining the lands contact until the cases are better fireformed.

If you load real hot without keeping the case back against the bolt head the case stretches significantly as others have mentioned. You may not get more than 2 loads before the head separates. It did that exact thing with my new .223 Model 700.

Regarding measuring lands contact, I have not had good luck with Stoney Point. I mention this as I had used the Stoney Pt equipment and had an overall reading of 2.732 fairly consistently. When I used the "dent the neck" method, lands contact came at 2.750 (.018 diff.) I mention this so you can be sure you are making positive contact with the lands to keep the case back against the bolt.
Ron

Chuck, I have an older Kreighoff Mauser 7X57 that had the primers backing out .010 to .012. I got lots of feedback here on AR about what to do to alleviate the problem. I ended up sending it to a recommended gunsmith to have it rechambered. After I got it back I had to work a little to get my reloads correctly resized to match the new chamber. But with the newly rechambered gun no more backing out primers (safety first) and it shoots REAL nice. If you would like the name of the barrel gunsmith let me know and I'll pass it along. He was very reasonable and quick turnaround too. I might add that he mentioned that if the gun has been rechambered once already it probably can't be rechambered again. Mike