What do you want it for? Recoil reduction or flash reduction?
Well, depending on where you live, you have various options.
For instance, if you lived near me, you could come here and do it yourself.
Well, I'm not sure. Does 7.62x39 actually have enough recoil to warrant a comp?
About all I have experience with is 20" AR's in 5.56mm, so I'm a little spoiled there.
Also, Kansas City, KS area, so Houston would be rather a bit of a drive.