Gunco Forums banner

Green moutan barrel blank (7.62x39)

15K views 63 replies 23 participants last post by  1biggun 
#1 ·
#36 ·
My .50 cal Green Mountain barrel has a noticeable burr on the muzzle end, which is also a bit smaller than the chamber end.

I don't have enough experience with blanks to know how common this sort of thing is. The bore was nice and shiny, so I decided to ignore it and continue.
 
#37 ·
on mine the burr end is a bit bigger. I im sure it makes a differance and Id like to know how to tell. the barrel is saw cut on both ends so Im sure it was cut. from a longer blank

Im guessing the burrs are were the tooling was pulled out of the barrel but I dont know if that the muzzel or the breach end. Im thinking you would want the bullet going the directionthe tooling was but I have no reall reasoning oter than any burrs or ruff ness would be pointing to the exit of the tooling. I think I need to call them and ask WTF.

This would make a really cool looking bull barrel gun maybe add a intrigal break like magna porting although I doubt there would be much of a kick with this heavy of a barrel.
 
#41 ·
That would be cool if they would offer a longer .311 blank I'd buy one I'm sure.

One thing I noticed though, is their 27x1.2 8mm blank for about 96 bucks. I totally am thinking of getting it and having it turned as thick at all its dimensions as possible while still accepting my m76 barrel components hehe is roughly 26 inches too much barrel for 8x57? It would be my super 76 hehe
 
#43 ·
Nice haha I need to get that blank then, though my m76 would maybe go from heavy to shoulder spasm heavy haha. But it would be cool. I can imagine it now if I keep it as close to 27 inches as I can with the flash hider it might be almost 30 inches haha awesome.
 
#44 ·
Id keep it a around 24" 26 being the longest. i dont think you will gain much after 24. rememaber the you only want as long of a barrel as needed to get the best velocity VS barrel stiffness the shorter the barrel the less it will walk and flex etc. If i could get the speed out of a shorter stiffer barrel I would. Unless your looking for a certain look Id gow ith a practical length. 8mm is pretty close to a 30-06 in case capacity etc and you seldom see 26: barreld 30-06's any more most are 22" or 24".

Im going to try a super heavy barrel pistol at some point with about a 13" barrel I think one of the reasons mY AMD 65 is more accurate than many of my 16" barrels rifles is that the short barrel is stiffer and actualy braced by the suoer tight fitting gas tube that holds my scope mount. If these GM barrels will give any type of decent accuracy then Ill try one on a hunting pistol. Im not expecting much for $30 BTW.
 
#45 ·
thanks big gun i was realisticly thinking somewhere between 24 and 26 inches. from what i've been reading there are some gains to be had with 8mm having a 26 inch barrel over a 24" when reloading and slower powder and it doesn't really seem to hinder factory/surplus perfomance, also instead of tappering like the factory m76 barrel i will have it step keeping each part of the barrel as thick as i can with it being just slightly smaller than the gas block all the way till the last few inches where i'll step it down for my front sight/fh. or is the gradual tapper the m76 has a better design?
 
#46 ·
Well I gave them a call. Talked to them about just labeling the land and grove dimensions of the barrel since it can be used for more things than 7.62x39. Also inquired about a longer barrel blank, they are looking at it but are going to be doing some AR barrels for a bit.
 
#47 ·
I ordered two of the GM blanks, which came in last week. I just checked the bores, and one is .314, the other .315 across the grooves.

All my AK barrels are in the shop at the moment, but my Mosin was handy and miked at .315.

This is just with a dial caliper.
 
#48 ·
I just checked the bores, and one is .314, the other .315 across the grooves.
HMMMMM they said they were air guaged at one point I think. it never said how tight they held there tolerances. I dont expect much for $30 but well see what they can do.

I have a ruger bolt action that was very very accurate Im tempted to screw a barrel on it to see defenitivly what is possable in a 7.62x39 perhaps a .308 barrel as well. the action has a 1"-16 thread so it would be doable.
 
#49 ·
Keep in mind a caliper is not the same thing as slugging the bore and throwing a micrometer on the slug. Calipers are great when close tolerances aren’t needed.
 
#51 ·
GM offers economy barrels AKA "biggest bang for the buck". I too am interested in 1BG accuracy test. He will show what to expect from these barrels. If it was my M76 I'd spend a little more money on a premium barrel (Shilen, Pacnor, etc...). If absolute accuracy is your goal with all the work involved don't cut corners as I doubt the GM 8mm barrel fill satisfy. Will say the GM 500 S&W barrel I use provides good MOP accuracy (minute of pig). I built it with 100yd accuracy in mind and my only kill opportunity was a 130yds on a 40LB Javelina. I'm getting 4" groups @ 100 with a Millett red dot. YMMV. willie
 
#53 ·
Is there any word on these barrels from someone who has ordered one? Im tempted to get a couple just as learning tools but it would be a nice side benefit if it would be better than the surplus barrels with good ammo. I know it all depends on if you can finish it right though.
 
#54 ·
For a $30 barrel they seem nice. Is it a top grade barrel? I don't think so.
But as you mentioned, for something to learn on, I think they would be perfect for that.

And welcome to the forum
 
#56 ·
Nice! I'm thinking of getting that 76 barrel. Now I talked to my machinist buddy and he said he could do a run of profiled but unchambered barrels on his cnc lathe, big gun, was that that you that was interested in unchambered profiled barrels?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top