Home Forums Hunting & Shooting Gunsmithing light primer strikes

My brother's Marlin X7 misfired 3 times this evening. After fooling with the bolt assembly, dissasembly, good shot of brake cleaner etc, we got to wondering if we were not fully closing the bolt.

I always thought if the bolt handle was not fully down the firing pin would not move at all, but we were getting light primer strikes.

We ran out of daylight to test the theory, so are we possibly on the right track, or is there some more logical things to check first?

The firing pin is still going to move, but unless the handle is all the way down, in battery, the cocking notch will not be aligned causing the cocking cam surface to interfere with the cocking pieces forward momentum. By the way, that's why bolt handles jump. Anyway, did this just suddenly happen? Factory or handloads?

Just with handloads, and bolt is all the way down. We were very deliberately testing this evening.

Even with the bolt up some, the factory loads always went off.

My model 70 shot all the handloads that we could not get the marlin to set off.

I'm beginning to think weak firing pin spring, as it is very obvious the dent in the primer is much lighter with the Marlin.

Possibly the Federal factory loads use a softer primer? my reloads use Winchester WLR.

How far are you pushing the shoulder back when you size your handloads? -Al

what al said!

Ed

That crossed my mind as I am full length resizing, but wouldn't the primer back out when we do get it to fire?

Also the headspace on the Marlin that is misfiring seems shorter than the model 70 that shoots the loads fine. I say that because when I misadjusted the dies last year, the loads would not chamber in the Marlin, but would chamber in the mod 70. After bumping the shoulders back the reloads fired fine in both rifles.

Any way I can measure a resized case on the shoulder?

I suppose I could have adjusted the die down a little more this year, but then I would think the Mod 70 really would have a problem, unless...
Would the claw extractor hold the shell enough to fire in the CRF 70? If that's the case I suppose I should look for case separation signs?

Bottom line..you have to know how far you're pushing the shoulder back on any handloads.

The best way is to use the Hornady/Stoney Point tool.
http://www.hornady.com/store/Lock-N-Load-Headspace-Kit-With-Body-1-Each/

Remove the primer from a fired case, and check the base-datum figure. Now you can set the f.l. die to bump the shoulder back .0015-.002. If you have two guns chambered the same, it's an easy matter to set the f.l. die up for the chamber with the shortest base-datum figure, then use a die shim (of the difference) to shim the die up for the 'longer' chamber.