Bear Creek AR-15 7.63x39 Firing Pin Spring??

[MrScharfenberger]

Hello All...

I'm a new guy to the forum and I have a question I've not been able to figure out on my own. I recently purchased a Bear Creek Arsenal AR-15 that fires the 7.62x39 Russian round. I love the gun, it hits hard & is cheap to shoot. My problem is that about 2 rounds out of every 30 don't go off. After being ejected I can see that the primer was hit & dented but no "BANG". Before buying the gun other people had mentioned in the reviews that this is pretty common and the fix is to replace the firing spring with a stiffer one. The only problem is I can't seem to find one. When I do find one I'm not sure I'll know if it is stiffer or not because I don't know the spec's on the stock firing pin spring.

If anybody knows where to get these I'd apprecaite it if you could post a link. Or at least a link to read the spec's on the stock firing pin spring.

Thanks in advance & I really enjoy this site so far.

C.S.

 

[easy]

None of my ARs have firing pin springs, all are free floating. Never heard of any having one either.

 

[<*(((><]

The 7.62x39 needs more firing pin protrusion to reliably ignite harder Russian primers then standard BCGs for 5.56. If I recall correctly the 7.62x39 pins should protrude 0.010” or so further from the bolt face than normal.

Some manufacturers mill the bolt face deeper to allow for more protrusion, have a longer pin, or turn the firing pin stop back to allow the pin to float forward further for more protrusion.

You may want to call Bear Creek and see what they do for the harder Russian ammo primers, it’s one of the three options above or none of the above. If none of the above you can buy an “enhanced firing pin” which is either longer length than stock OR has had the pin stop milled to allow for further protrusion.

You will need to check your firing pin protrusion from the bolt face compared to a 5.56 to see if it protrudes further. I don’t know if you have the means/tools to do so or not, but you could take it to a gunsmith and have them measure and compare the two protrusions between it and a standard BCG

 

[greyling22]

You could also just try and grind the hook off your hammer to increase the speed it hits with. It is what jp does to its hammers. There might also be an increased power hammer spring. Does a 2nd strike set off the rounds that didn't fire?

 

[MrScharfenberger]

The 7.62x39 needs more firing pin protrusion to reliably ignite harder Russian primers then standard BCGs for 5.56. If I recall correctly the 7.62x39 pins should protrude 0.010” or so further from the bolt face than normal.

Some manufacturers mill the bolt face deeper to allow for more protrusion, have a longer pin, or turn the firing pin stop back to allow the pin to float forward further for more protrusion.

You may want to call Bear Creek and see what they do for the harder Russian ammo primers, it’s one of the three options above or none of the above. If none of the above you can buy an “enhanced firing pin” which is either longer length than stock OR has had the pin stop milled to allow for further protrusion.

You will need to check your firing pin protrusion from the bolt face compared to a 5.56 to see if it protrudes further. I don’t know if you have the means/tools to do so or not, but you could take it to a gunsmith and have them measure and compare the two protrusions between it and a standard BCG

Thanks for the reply. That is very helpful. I do have the tools to measure it myself. I'll measure the protrusion on my Windham 5.56 AR and then compare that to the Bear Creek 7.62 firing pin protrusion. I know a lot more about motors & transmission that I do guns but I'm learning.

You could also just try and grind the hook off your hammer to increase the speed it hits with. It is what jp does to its hammers. There might also be an increased power hammer spring. Does a 2nd strike set off the rounds that didn't fire?

No. I've re-tried each round and they will not fire once the primer has been dimpled. Perhaps a hammer spring is what the others were referring to that reviewed this gun. They said once they put in a new spring the problem went away.

...no wonder I could not find anything about an AR firing pin spring. I love it when I look like a genius on the internet.

 

[<*(((><]

Once you have the correct protrusion and if you are still having problems then you would change your hammer spring to a heavier one. But my guess is with the correct protrusion it will ignite reliably. I have a AR47 and have had no problems for ~800 rounds of various steel case Russian ammo and have had no ignition problems. And I’ve used a milspec trigger for about 500 rounds with no problems and then the last 300 or so rounds have been with a LaRue trigger and no problems there either.

I just did a quick search and it seems the correct protrusion difference between standard and 7.62x39 is +0.012”-0.015” depending on brand.

 

[MrScharfenberger]

Reporting back:

I took the rifle out to Knob Creek in Kentucky this afternoon and ran about 250 rounds through it. In the 2nd magazine I had ever run through it I had 3 rounds that didn't go bang. Same as the first magazine. After that it never missed a beat and fired the other 220 rounds with no issues at all. Perhaps it was simply a "break in" thing. All rounds used were Wolf. I had put a Cabela's StrikeFire 3x red dot on it. I dialed it in and was killing oil bottles @ 75 yards. I love this rifle. It hits a lot harder than a 5.56. It has more kick but it is very manageable unlike my AK. The AK puts on a good show but I struggle to hit things with it.

 

[<*(((><]

Good to hear, I love mine, it’s my favorite AR to shoot right now. I have a preference for cheap calibers so it hits home there and the punch it gives is sweet.

Like I said before I’ve bought a host of different ammo to see reliability with mine and it’s been utterly reliable so far.

I have a primary arms red dot with a flip to side 3x magnifier and love the setup for the cartridge