Protruding Fired Primers

[SUB VET II]

Most rounds fired yesterday resulted in the primers protruding from case head.

Load is 48 grains 4895w/150 gr. SHPBT. Primer Win. Do I have a head space

problem? Comments and thanks in advance.

Information

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[MEHavey]

If that's 30-06, that is a classic mild 2700fps/40,000psi load

But also since the case apparently did not stretch back to reseat the primer, you can't necessarily check by looking/measuring the headspace of the fired case.

Out of curiosity, what *was* the case stretch (if any)?

[SUB VET II]

Case stretch--None--

[slamfire1]

These cases had a load of 150 SMK 47.5 grains IMR 4895 CCI #34 primers. Fired in a M1903A3 (I think)

The primers are backed back, about .003".

This is a classic case of low pressures a clean chamber and clean ammo.

When the primer ignites the powder charge the pressures rise. A couple of things happen earlier on, pressure locks the case neck to the front of the chamber and the primer is backed out by pressure. Then as pressure builds, the case body stretches to the bolt face, effectively stuffing the primer back in the pocket.

In this incident, the pressure was not enough to stretch the case. (Which is just fine, as too much case stretching will create case head separations)

If the case was lubricated when fired, the whole case would slide to the bolt face never letting the primer back out. On less than max loads, you will find that the primers on lubricated cases often have rounded edges, where the same load in a dry case, the primers are flattened. Due to the primer being stuffed back in the case after sidewall expansion.

[SUB VET II]

Thank you "Slam Fire" Am going to increase load to 49gr's of 4895 from the previous 48gr's. My 03's do well with 48 grs.

[snakehunter]

If I were you, I'd try 5 rounds at 48.5gr first.

[Mike]

Hi,I'd try some factory ammo, or have your head space checked.Regards,Mike

[Devil Dog]

I have found that 46.5 grains of IMR4895 over 150 grain bullets is my most accurate load. As I increase powder my accuracy suffers. Maybe you should put up with some primer protrusion.

[slamfire1]

If you are shooting these loads in a Garand, 48.0 grains is as high as you should go. At least in my opinion. This rifle was fielded in 1936 with ammo that is not hot by todays standards, and yet was specifically tailored to the operating system of the rifle.

I tested my loads in several rifles. In a Garand I want to be below 2700 fps with a 150. When I have chronographed 50's military ball, that stuff runs under 2700 fps. So that is where I want to be with my reloads.

I found 47.5 grains to be an accurate load and in my opinion, close to max in a Garand.

M1 Garand 5 827 ZZZ Standard Grade Rifle


150 gr Sierra Match HPBT 47.5 IMR 4895 CCI#34 WWII cases OAL 3.290
24 Mar 04 T= 70 ° F

Ave Vel = 2619
Std Dev = 28
ES = 101
Low = 2559
High = 2660
N = 16

M1 Garand 5 925 ZZZ Standard Grade Rifle


150 gr Sierra Match HPBT 47.5 IMR 4895 CCI#34 WWII cases OAL 3.290
24 Mar 04 T= 70 ° F

Ave Vel = 2630
Std Dev = 33
ES = 109
Low = 2580
High = 2689
N = 16

[SUB VET II]

Thanks all for excellent input. Yes 49 grs of 4895 may be a little high for the rifle. In their declining youth (as mine) something might break. Will ponder the question and report results. By the by; anyone else with primer protusion?