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Posted: 2/14/2016 11:20:09 PM EST
[Last Edit: 2/15/2016 2:01:04 AM EST by WaltARAK]
I recently purchased a Faxon 7.62x39 piston upper and their stripped AR lower. I installed a Geissele SSA trigger that ignited Wolf 7.62x39 without problem during the barrel break-in protocol. However, I purchased 500 rounds of Golden Tiger 7.62x39 and that's when the problems began. I had about 15% FTF, although most FTFs ignited on the 2nd attempt. At about the 200 round mark, I installed a Wolff Extra Power hammer spring. I still had about a 15% FTF with the remaining 300 rounds or so of the GT.

In between, I successfully ignited more 7.62x39 Wolf, and then Tula and Hornady SST. Faxon sent me a replacement firing pin and I also tried a Black Rifle Arms enhanced 7.62x39 FP. Same FTF issue with the GT about a 15% FTF.

I used calipers to measure the FP protrusion from the bolt face. I measured from the lugs/lip to the bolt face, and then the lugs/lip to the tip of the protruding pin - and took the difference between the two measurements. The Faxon FP gave the most pin protrusion at .049".

My understanding is that Baranul makes commercial ammo for Bear, Wolf, and Tula - all of which use a SAMMI spec primer for commercial export loads, which is softer the mil-spec primer used by GT. I took a look at the primer strikes on the empty Hornady casings and they did look deeper than the primer strikes on the GT that ignited. Regardless, shouldn't the Geissele SSA with the Wolff XP hammer spring ignite the GT with as much success with the Wolf, Tula and Hornady? Any comments and suggestions will be appreciated!

Here is a picture of 11 rounds (2 that did not ignite)

Link Posted: 2/14/2016 11:48:34 PM EST
It has been a recent problem. I haven't had any problems out of my recent batch.

Link Posted: 2/15/2016 2:29:47 AM EST
Thanks MP. I didn't know that. Here is a sample of what I experienced:

Link Posted: 2/15/2016 8:27:20 AM EST
Link Posted: 2/15/2016 11:08:04 AM EST
The consensus of a couple long gun Yodas at the range also attribute the GT FTFs to faulty ammunition and not the weapon - in particular the firing pin that appears to have done its job based on apparent adequate primer strikes. From the picture, and especially in person, it appears that the two GT rounds that did not ignite had their primers cave inward - a distinct difference from the primers that did ignite, including several successful rounds of GT. As mentioned, the Geissele SSA and a Wolff Extra Power hammer spring along with .049" of firing pin head protrusion from the bolt face should all equate to robust primer strikes. Maybe I just received a bad production run of the GT, although a 15% FTF rate out of 500 rounds is rather disheartening when considering that all other 7.62x39 ammo (Wolf, Tula and Hornady SST) ignited without issue from the same weapon albeit with the Wolff Extra Power hammer spring.

Incidentally, here is an informative summary of certain primers:

Regarding the Faxon 7.62x39 upper and stripped AR lower that I built-out, it has functioned flawlessly aside from the FTF GT ammo. The only jam was a single round of Tula that upon inspection had a burr on the casing near the primer that caused it to misfeed. I keep the gas selector knob usually at the minimum setting. The CPD 30 round mags have also functioned flawlessly after just over 500 rounds. It's an enjoyable platform.
Link Posted: 2/15/2016 11:35:12 AM EST
Link Posted: 2/20/2016 11:09:52 PM EST
Now it appears that I have to give the the Russian Golden Tiger 7.62x39 ammo the benefit of the doubt. I decided to re-replace the Wolff Extra Power hammer spring with another one of the same from an authorized Wolff dealer just in case I received a bad one off of eBay. Also, I took about .002" off the bolt tail so that the firing pin protrusion is now about .051 from the bolt face.

I then fired the remaining GT from the same lot that previously had about a 15% FTF rate. Sure enough, all GT fired without problem including several more rounds of GT from a new lot. Research shows that an AR-AK platform needs at least a .050" firing pin protrusion to ignite some of the hearty Russian primers. The added firing pin protrusion resulted in not a single FTF with the GT but also with Hornady SST and Wolff 7.62x39.ammo.

Lesson learned.
Link Posted: 2/21/2016 2:53:51 AM EST
[Last Edit: 2/21/2016 3:02:51 AM EST by Hilljack]
Have some older GT that my Maadi will not set off. Primers are set too deep, I'd guess. Had some trouble getting some of it to ignite in an AR(Faxon barrel) also. Did the firing pin mod and all of it goes bang now.
Link Posted: 2/21/2016 11:11:54 AM EST
Yeah, it's amazing what an additional .002 - .003 firing pin protrusion will do. I'm really pleased with my Faxon AK upper.
Link Posted: 2/23/2016 8:36:09 AM EST
Manufacturers can only make enhanced firing pins protrude so much or it puts piercing primers on other ammunition at risk. I would have stuck with steel case ammunition like Wolff than to go with ammunition like Tula or Golden Tigers that have known issues with deep set primers, and felt comfortable in knowing I can switch between it and brass without concern of possibly piercing primers.
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