Excess Firing Pin Protrusion?

[slappomatt]

I just got my new 6br back from pac-nor and durring my first match i had 2 rounds shear a small circle out of the back of the primer and it jamed the firing pin to the point that i had 12 or so rounds miss-fire. all durring a timed match.

the load was CCI 450/lapua 6br .272 neck sierra mk 107's 30gr varget/ .020 seated into lands of 28" 3 groove 8 twist heavy super match barrel. I saw the little circle of primer that it cut out. is this the same as primer peircing? the bolt lift was no problem. the firing pin seems to be about .05 or so sticking out of the bolt face. is that excessive? thanks!

 

[WayneShaw]

You don't say what action you have, but .050" is about right. I would look at the firing pin to pin hole clearance. It should probably be bushed for a tighter fit and smaller diameter. This should solve the blanked primers.

CCI's are the toughest primers, so you gotta fix what's wrong. But, every barrel is different, and you have to adjust your load for each.

 

[BoydAllen]

The technical term for what you describe is primer blanking. Check your firing pin spring tension and or firing pin weight in combination with spring weight. A lighter replacement pin makes having a heavy enough spring critical. But with a hot load a lazy spring combined with excessive tip clearance might cause the problem.

 

[slappomatt]

I have a remington SA action. I will be sending the bolt out to GREYTAN rifles probably today or tomorrow for bushing and ceramic coating. and I'll see how it goes from there. thanks for the advice!

 

[slappomatt]

well the bolt came back last thursday. looks great. the ceramic coating looks alot better than the mostly worn off parkerizing of the old bolt. with a little oil it works pretty smoothly. and the firing pin looks nice. Greytan was rec'ed by the 6br staff so i went with him. nice guy and very fast turn around. I would certainly 2nd their advice if you need any gunsmithing.

im thinking of having him add an external bolt top to my remington as my shilen trigger has no provisions for a bolt stop, and i just like the look of the action bolt stops. has anyone had this done to a factory action?

 

[Wild_Bill]

Hi the CCI primers are not the hardest the Remington 7 1/2 are much better they will fail last behind all other small rifle primers and a side they are hotter so they ignite slower powders well to. Try them and i will bet you may have better luck but i would also look at bushing the firing pin hole as that is the issue not the petrusion. Havi ti bushed to about 60-62 thou with 1 thou clearance on the radius.

Cheers Bill
Australia

 

[tmbryant]

I was talking with George Kelbly at the Hog Roast this weekend and we were discussing mainly Kelbly's new benchrest trigger. The subject of blanked primers was brought up. George said that they found that most times when primers are blanked its caused by the shoulder being pushed back too much when sizing cases. They had even found shoulders were being pushed back as much as .020". You might check to make sure that the shoulder is being pushed back no more than .001 to .002" when you are sizing the cases. I've been shooting a 6 Dasher and have had trouble with blanked primers, but have not checked to see how far the shoulder is moved back upon sizing. If you are shooting a Jewell trigger, you need to be especially careful not to blank primers as I had two triggers brought in a week ago that had broken pieces inside the trigger from the cocking piece blowing back from blanked primers and then slamming into the top trigger bar.