M1 Garand reloading primer issue

[Txwingshooter]

While not new to reloading, I have not experienced this before. I am using new Remington brass, WLR primers, 45 grs of IMR4895 with 168 grain HPBT bullets. The issue is that the primers are backing out on every round. I have reduced the load to 40 grains and have the same result. Overal length is right at the recommended max. I also had the same issue with factory M1 match 168 grain ammo. Any thoughts will be appreciated.

 

[cheygriz]

Switch to Remington 9 1/2 primers. They're Milspec.

 

[Walkalong]

Primers backing out is generally a low pressure thing, but I have no experience loading for Garands yet, as I just recently became a Garand owner. I have only loaded .06 for a bolt gun.

I'll be keeping an eye on this one.

Welcome to THR

 

[243winxb]

I also had the same issue with factory M1 match 168 grain ammo.

Very strange with factory, should not happen. A handload with to light of a powder charge might let the whole primer back out with new Remington brass. Or is the primer extruding in to the recess around the firing pin with the factory ammo? A photo would help, or check the photobucket link below for primer photos.

 

[MEHavey]

Normal firing pin strike first pushes the whole case forward in the chamber until it is stopped by by (a) the case shoulder hitting the chamber shoulder; or (b) the extractor. Normally, pressure expansion then locks the forward portion of the case to the chamber wall and (1) the primer immediately backs out of the case to meet the bolt face; and (2) the case then stretches back to meet the bolt face as well -- reseating the primer flush.

QUESTION: How much is the case stretching before/after firing?
QUESTION: Who is loading the factory M1/Match cartridges you mention? (Federal/Hornady/Other?)

DIAGNOSIS OPTION #1
Your 168HPBT/45gr/IMR4895 loading combination is not producing sufficient pressure to stretch the case back to the bolt face and reseat the primer. Lowering the powder charge just makes it worse. Kick the 168gr/IMR4895 powder charge up to "standard" [in YMMV quotes] 46.5-to-47.0gr
http://masterpostemple.bravepages.com/M1load.htm

DIAGNOSIS OPTION #2
Your Grarand's headspace is waaay over spec and the case cannot stretch beck enough to meet the bolt face at normal pressures. What is the source/pedigree of your Garand? (DCMP/Modern Commercial/Unknown?)

 

[243winxb]

Lets make sure we are talking 30-06 Springfield Caliber?? Not the 308 win. ?

 

[Txwingshooter]

Interesting responses - the rifle has just been rebarreled by Springfield and this was part of the break in if you will. The factory match ammo is Hornady. I just loaded and fired 3 rounds using Remington brass and CCI LR primers and did not have the same issue. I will work up to the higher loads tomorrow and see what the results are. Yes we are talking 30-06. I have not measured case stretch but will do so - started at 2.490. Thanks to all.

 

[USSR]

Yep, low pressure. 47.0 grains should take care of that problem.

Don

 

[rodregier]

Priimer pocket and primer diameter vary slightly from mfgr to mfgr. Given the suspected underpressure issue some primers could release from the pocket more easily than others.

If you tried two different mfgr primers in the same pockets you would probably find some difference in the amount of force necessary to seat the primers to the bottom of the pockets.

 

[medalguy]

I agree with low pressure. I load 168 gr Sierra HPBT in '06 with "more than 45 gr" of IMR4895 and don't have that problem. Try upping your load to say around 47 gr as suggested by USSR and see if they look better.