JP EZ kit and broken 9mm firing pin

[blaster113]

I finally got the disco adjusted in my JP Ez kit so no more doubles/full auto. Lower is CMMG with KNS pins. Had the red spring in and was getting light strikes with CCI SP primers (sucks ass for 9mm, don't seat all the way. Fine in.40). Put in a gray hammer spring from a JP service rifle kit. That helped some with the light strikes, but then the firing pin in my CMMG bolt broke. Had a CMMG 9mm buffer and regular carbine spring in at the time.  The fired cases look unusual also.  The cases used to have the usual round hits, but now I swear the primers look like they came out of a major 9 Open gun. My load is 135 pf; a 125 gr BBI at about 1080 fps. 

 

At ignition, is the light hammer insufficient to properly keep the bolt in battery? My guess is I need to put back my extended heavy buffer and most likely the XP buffer spring. 

 

Im ready to rip all the JP stuff out and throw it in the trash. Or it'll be on sale in the classifieds very soon?.

[Aircooled6racer]

Hello: Try a 308 carbine spring with the 9mm buffer. Looks like some primer flow into the firing pin hole maybe caused by the bullet hitting the rifling from a short throat chamber? Could be unlocking too quick but the cases would be all blackened and you would see gases/flames coming out the ejection port. Don't ask. Thanks, Eric

[CZ85Combat]

That primer flow has nothing to do with JP parts.

[blaster113]

I have an XP buffer spring, that should take care of the primer flow?

 

never seen primer flow with the oem fire control parts, even when I used a regular carbine spring and 9mm buffer

[blaster113]

Must've had a bad firing pin which probably led to the primer flow before it finally broke in half.  Put the XP buffer spring back in, new firing pin, and even with a red hammer spring the JP kit is 100% and primers look good.  Man the JP trigger is nice, even at 4.25 lbs.  Now only bad thing is there's no excuse for missing a target...

Edited January 30, 2017 by blaster113
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