7.62 x 39 upper question

[GB in WY]

I think this is the proper place to ask about what I need to change, if any thing, so that I won't damage the gun (or me!). What, if any, change is need to shoot a 7.62 x39 upper with a stock M4 clone lower? Do I need to change the buffer (maybe a heavier one?) or buffer spring?(again maybe an extra strength one?) I have fired a few rounds and while I had zero issues with function, I did notice more recoil and don't want to break anything. While I have some experience with the AR platform, it is mostly with stock 5.56/.223 guns and I have decided that I should build, or have built, a dedicated lower for this upper and think it makes sense to ask if I need to do anything special to make it last as well as function. Any thoughts? Thanks in advance.

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[browningautorifle]

I run an H2 buffer anyway and you can start there and go to an H3 if you're still uncomfortable. I don't think you'll hurt anything anyway. Change the bolt and barrel, mags and get out and warm it up. Lower is the same.

[GB in WY]

Thanks, Jim!

[fjruple]

I found that I had to put an extra power hammer spring into mine due to light primer strikes on the military Russian 7.62x39mm cartridges.

--fjruple

[browningautorifle]

an extra power hammer spring

That could easily be a fact...

[MikieG]

I built a midlength gas length, 16", piston driven rifle. To get it to run wslmart tula ammo, i did the following...
1 opened gas port to .125".
2 used the light weight Adams Arms BCG
3 chose MGI HYDRA super bolt
4 installed Wolf extra power hammer spring
5 used LWRCI adjustable recoil spring anf Lwrci buffer piston.
Rifle runs all x39 mag mfgs mags reliably.
I am very happy with rifle.

[m1903rifle]

Just get a 300 AAC upper and forget the 7.62X39. Not a lot of difference down range and you can use the regular AR-15 mags.

[browningautorifle]

get a 300 AAC upper and forget the 7.62X39.

With the ammo availability in the US, I'd agree. Here in Canada though, we still have to make 300 to make it affordable.