High primer and misfires in 30-06

[altitude_19]

I've been getting a lot of high primers and a few misfires. I'd say around half (or more) of my primers are high after discharge and 1-2 out of 20 rounds don't fire. Cartridge is 30-06 110 JHP over 47.6 gr IMR 3031 in twice fired brass (3rd loading). Can the primer pockets wearing out cause this? Is it strange it's happening so much when the brass is only on it's third loading?

 

[MtnCreek]

I'd say around half (or more) of my primers are high after discharge

You have too much head clearance, otherwise they wouldn't have room to back out.

1-2 out of 20 rounds don't fire

Most likely due to not seating them all the way in.

Can the primer pockets wearing out cause this?

If the pockets are loose when seating a primer, you've probably shot some at high pressure, considering you've just got 3 loads on them.

 

[243winxb]

110 GR. HDY SP IMR IMR 3031 .308" 3.170" 51.0 3252 47,200 PSI 54.9 3471 57,800 PSI Your below the starting load thats on the Hodgdon website.

 

[morcey2]

You're running below the minimum load, at least according to the Hodgdon load data. That's not necessarily a bad thing, but you can end up with some high primers due to low pressure.

When the primer is first ignited, it actually backs out of the primer pocket as space will allow. Once the pressure is high enough to force the case rearward flush with the bolt-head surface, the primer is reseated flush. I see the same thing with 8x57 domestic lawyer-loads in any of my mausers. Almost all of them will close on the no-go gauge, but none close on the field gauge.

The backed out primer is annoying, but generally harmless. You need to figure out why you're getting misfires. That's never a good thing. I don't know if 3031 is position-sensitive, but I don't think it is to a great extent. Are you getting a good, deep, solid dent in the primers?

Matt

ETA: what 243winxb said.

 

[altitude_19]

They are all seated by hand and below flush. Re-strikes don't set them off. Load data is from the Speer manual (using a Speer 1835 bullet) and I'm running ABOVE minimum load. These clock about 2850 FPS. I have been FL resizing and trimming to recommended length (2.484).

 

[rcmodel]

You can be creating artificial excess headspace by pushing the shoulder back too far during FL sizing.

That sets the case too deep in the chamber for some firing pins to hit the primer a full blow.

And also gives the primers room to back out when fired.

Back off the sizing die until the bolt will just close with slight resistance on a resized but empty case.

rc

 

[30Cal]

Agreed. Sounds like excessive headspace situation.

 

[ArchAngelCD]

You can be creating artificial excess headspace by pushing the shoulder back too far during FL sizing.

That sets the case too deep in the chamber for some firing pins to hit the primer a full blow.

And also gives the primers room to back out when fired.

Back off the sizing die until the bolt will just close with slight resistance on a resized but empty case.

rc

This is sound advice and will probably solve both your problems...

 

[gamestalker]

From what I can tell, you are significantly below the starting charge, which can certainly cause some issues with primers backing out. I would also venture to guess your cases are pretty sooty, and possibly even pressure dented at the shoulders or wall. Use published start charges, they have been developed to produce minimum to maximum operating pressures.

As for mis-fires, it is possible for a sub level charge to have sporadic ignition problems, though I've never seen it happen. I would be more inclined to think that those primers aren't completely seated. Primers need to be seated at least .004" below the case head, or until you can feel the anvil preloading against the bottom of the pocket.

And it is also possible that the oal os too long, thus causing the bullets to rest up against the lands. When the firing pin strikes the primer the cartridge will move forward, which displaces the energy of the FP strike. And if the brass is not properly head spaced, the projectile will be creating a false head space, which can definitely cause mis-fires.

GS

 

[morcey2]

gamestalker, he's looking at the jacketed HP pistol-style bullet in the Speer manual. He's just a hair over the max load in that listing for 3031. I'm looking at it right now, so he is using published data. If you look at the 110 gr rifle bullets (next page), it is under the max load but I don't thing the bullet he's using will handle the velocities a full load would give.

I do completely agree with your conclusions though.

Matt

 

[gamestalker]

Thanks for the heads up Matt!

GS

 

[243winxb]

Misfires

Misfires-clean the bolt and/or firing pin channel. Oil that has dried may slow the pin. Can even happen with a new rifles in cold weather. Lazy, spray bolt with WD 40.