Light primer strikes

[Grizz1148]

Sorry if wrong forum.
I've had 5 out of 90 what I'm assuming are light strikes with a new rifle.
After removing bullet and powder I chambered the primed empty brass and they all fired. Measured firing pin protrusion and best I can tell it's .046-.047 which from my understanding is what bighorn says it's supposed to be.
Big horn sr3 action
Proof steel barrel
Peterson brass
Cci br4 primers
Any ideas? Don't have headspace gauges but fired brass measures .003-.004 longer than new brass.

 

[DoneNOut]

Do protrusion .049

 

[Varmint Hunter]

Excessive headspace allowing the cartridge to move forward and lessening the impact of the firing pin.
Just a wild guess.

 

[DoneNOut]

Excessive headspace allowing the cartridge to move forward and lessening the impact of the firing pin.
Just a wild guess.

Primers should be backing out then. Don't know. Not enough info.

 

[Grizz1148]

Do protrusion .049

Do protrusion .049

How is that done on big horn bolt?

 

[Grizz1148]

Primers should be backing out then. Don't know. Not enough info.

Primers weren't backed out. Wouldn't excessive headspace show up in the fired case measurements?

 

[DoneNOut]

Backed out primers will show excessive headspace. You have a case comparator to check fired vs unfired?

 

[Grizz1148]

Backed out primers will show excessive headspace. You have a case comparator to check fired vs unfired?

Primers weren't backed out as far as I could tell. I measured the shoulder of new and fired cases as stated in the op. Fired were .003-.004 longer.

 

[DoneNOut]

Not a headspace problem then. I've had brass elongate .020" after firing. So, you got a firing pin protrusion issue.

 

[Timeout]

Primers weren't backed out. Wouldn't excessive headspace show up in the fired case measurements?

It should show up when measuring a fired case. Were these handloads? Excessive moving of the shoulder rearward when full length resizing will result in your unfired cartridges exhibiting light primer strikes. Load and fire one case 3 times, measure the shoulder to base and set your FL die to "bump" the the shoulder back .001" - .002". If you don't have the equipment necessary to take the measurements, you can remove the firing pin assembly and the ejector and bump the shoulder back until the bolt just closes with a very light or minimal resistance. Back 50 years ago when I didn't fully understand the reloading processes, I had a rifle getting some FTF's which exhibited light primer strikes. I took the rifle to two different gunsmiths and they correctly said nothing wrong with the rifle. Frustrated, I sold the rifle. The whole ordeal was simply me not having my FL sizer die set correctly and shoving the cartridge shoulder rearward too far.

 

[Timeout]

Not a headspace problem then. I've had brass elongate .020" after firing. So, you got a firing pin protrusion issue.

There is a serious problem with brass elongating .020", especially if you are talking base to shoulder.

 

[Grizz1148]

It should show up when measuring a fired case. Were these handloads? Excessive moving of the shoulder rearward when full length resizing will result in your unfired cartridges exhibiting light primer strikes. Load and fire one case 3 times, measure the shoulder to base and set your FL die to "bump" the the shoulder back .001" - .002". If you don't have the equipment necessary to take the measurements, you can remove the firing pin assembly and the ejector and bump the shoulder back until the bolt just closes with a very light or minimal resistance. Back 50 years ago when I didn't fully understand the reloading processes, I had a rifle getting some FTF's which exhibited light primer strikes. I took the rifle to two different gunsmiths and they correctly said nothing wrong with the rifle. Frustrated, I sold the rifle. The whole ordeal was simply me not having my FL sizer die set correctly and shoving the cartridge shoulder rearward too far.

These were handloads on new Peterson brass.

 

[Grizz1148]

There is a serious problem with brass elongating .020", especially if you are talking base to shoulder.

Never said that. Said .003

 

[DoneNOut]

There is a serious problem with brass elongating .020", especially if you are talking base to shoulder.

300WM pretty routine since it originally headspaces off belt.