223 ignition issues

[jpmimproved]

Been working up a load for a 223 I had built a while back, and having a couple of issues with ignition. I’m thinking it may be a weak firing pin spring, but wanted some more seasoned shooters input. Out of 27 rounds, I had two fail to fire, and even fairly moderate loads(24-25.4 grns H4895), the primers were cratering significantly, but no anvil. No other pressure signs, case heads look clean and no sticky bolt.

 

[jpmimproved]

The primer on the far right is a new primer for comparison

 

[L.Sherm]

New Brass or once fired in your chamber?

 

[jpmimproved]

This was new lapua. .004” shorter at the datum than once fired

 

[jepp2]

I’m thinking it may be a weak firing pin spring

What rifle, how old? If you suspect the firing pin spring, I would disassemble and degrease the firing pin assembly and the inside of the bolt. I have had more issues with old grease than I have weak springs.

If I have a primer that fails to fire, I always try to fire it again. If it fires on the second strike, it probably wasn't seated properly to start with.

Is the cratering new? Your primers still have the radius at the shoulder (sometimes when the case datum to head length is short it will give the appearance of pressure as the primer gets driven out of the case, and then reseated into the case) but yours don't have that.

 

[jpmimproved]

I have decreased the bolt, I don’t run any lubricant on the firing pin besides a little dry graphite.

I actually did try firing it again, and it did not fire. After the first strike, they looked like very shallow indentions. I never had any failure to fires with CCI 200s, but just switched to rem 7 1/2s. I have almost always have had cratering with this rifle, and even some pressure issues with mild loads, having ejector swipe even with standard factory loads in Norma brass. I did have some concern that I may have had a carbon ring building pressure, as when I cleaned it after FAR too many rounds, it had a lot of build up ahead of the chamber.

 

[SWRichmond]

More Lapua factory brass with short headspace? This has been an issue with their 308 palma brass.

 

[gzig5]

What action do you have? I'd say you have something dragging, slowing the FP fall down. Check the cocking piece, safety and trigger.
Or, as mentioned, very short cases. If you can, neck up to 6mm and then back down and resize so you have a tight fit (zero headspace) in the chamber. That would rule out the brass. the PF hole looks large too, but hard to say if you have a light spring that isn't pushing back on the primer during firing.
FP springs are cheap, just throw a new standard weight in.

But, try one thing at a time so you know what the solution is.

add...you say you've had cratering issues in the past? I'd bet there is primer parts or junk limiting the FP fall in the front of the bolt. Pull it apart and clean the interior of the bolt thoroughly. Then get the bolt FP hole bushed. That is likely the source of your "pressure problems"

 

[jpmimproved]

It’s a model 7 action. Bushing the bolt is probably the next step. I have considered jamming the bullet when first firing new brass in order to fireform. If it’s a headspace issue, would this be a resolution?

 

[Pawnee Bill]

Send the bolt to Greg Tannel and have him put his firing pin and spring in your bolt and bush the firing pin. Problem solved.

 

[gzig5]

J-lock? I have two M7s that came with the J-lock and the spring does drag like hell in the bolt. They shot fine, but I replaced with PTG FP assemblys with standard weight pins just for piece of mind.
I agree that sending to Tannel is a good idea. Just make sure the cocking piece isn't dragging on the trigger housing excessively.

Seating a bullet .010-.020" long and then closing the bolt on it should clarify the headspace aspect of it, but I've never seen primers look like that which were fired with normal powder charges. I'd be surprised the heaspace would be that short. Case in point is some new 222 Mag brass I have. About one in five is .010" short in headspace. Other than ruining a decent group, that brass doesn't look any different than the others after firing.