7.62x39 Ar-15

I'm thinking of a 18" or 20" barrel, it has more to do with I already have a bunch of 7.62x39 and don't want a be running a bunch of different calibers.
I've seen a few tests done with x39 ar-15's with different types of ammo, the results run from 5 inch groups and 1inch grounds at 100m. A lot of the test were done with Ar-15's with 14-16inch barrels.

As for a target rifle I've been thinking of going with a bolt action 5.56.
 
Hermid said:
I'm thinking of a 18" or 20" barrel, it has more to do with I already have a bunch of 7.62x39 and don't want a be running a bunch of different calibers.
I've seen a few tests done with x39 ar-15's with different types of ammo, the results run from 5 inch groups and 1inch grounds at 100m. A lot of the test were done with Ar-15's with 14-16inch barrels.

As for a target rifle I've been thinking of going with a bolt action 5.56.
Click to expand...

cz 527
 
Hermid said:
I'm thinking of a 18" or 20" barrel, it has more to do with I already have a bunch of 7.62x39 and don't want a be running a bunch of different calibers.
I've seen a few tests done with x39 ar-15's with different types of ammo, the results run from 5 inch groups and 1inch grounds at 100m. A lot of the test were done with Ar-15's with 14-16inch barrels.

As for a target rifle I've been thinking of going with a bolt action 5.56.
Click to expand...

Why 18-20"?
 
Hermid said:
I'm thinking of a 18" or 20" barrel, it has more to do with I already have a bunch of 7.62x39 and don't want a be running a bunch of different calibers.
I've seen a few tests done with x39 ar-15's with different types of ammo, the results run from 5 inch groups and 1inch grounds at 100m. A lot of the test were done with Ar-15's with 14-16inch barrels.

As for a target rifle I've been thinking of going with a bolt action 5.56.
Click to expand...
Word of advice about choosing the length of the gas system for 7.62 in a 18" - 20". Select the mid length over the rifle and ensure the port size is large enough.
 
TheWhole9Yards said:
Why 18-20"?
Click to expand...

Better accuracy, 20inch would be ideal if they ever reclassify the AR-15 by barrel length, because an M43 AR-15 would be ideal for deer hunting.

Also how heavy are the NEA barrels?

I also found this: ht tp://www.luckygunner.com/lounge/762x39-accuracy/
 
Sqr said:
Word of advice about choosing the length of the gas system for 7.62 in a 18" - 20". Select the mid length over the rifle and ensure the port size is large enough.
Click to expand...

Does this apply to carbine length? The port size need to be large too?
 
I mite do a custom build:
Thinking of this: ht tps://www.ar15part.com/product-p/20762x39ssu1x10fsg2exrl.htm
 
SteelCap said:
Does this apply to carbine length? The port size need to be large too?
Click to expand...
A Carbine length for a 7.62 is more forgiving when shooting a wide range of quality or inferior ammo. As for the gas port, it is proportionally larger in 30 Caliber then it is for the 5.56 for the same barrel lengths. Personally I would select a mid length over a Carbine system for a 16" and greater 30 cal.

A 30 caliber AR15 can be controlled more easily when it is Carbine over gas then under gassed from a rifle length gas system. Utilizing heavier buffers, FA BCG's, buffer springs and adjustable gas blocks is common place for carbine gas system 16"-20" barrels. An under gassed 30 caliber is very very frustrating to fine tune, believe me on that one.

You will notice that many 300 AAC and 7.62's long barrels are routinely fabricated with the majority Carbine and secondly Mid length GS. Even a few companies fabricate 16" - 18" in pistol length systems, however I would avoid these.
 
Last edited:
Sqr said:
A Carbine length for a 7.62 is more forgiving when shooting a wide range of quality or inferior ammo. As for the gas port, it is proportionally larger in 30 Caliber then it is for the 5.56 for the same barrel lengths. Personally I would select a mid length over a Carbine system for a 16" and greater 30 cal.

A 30 caliber AR15 can be controlled more easily when it is Carbine over gas then under gassed from a rifle length gas system. Utilizing heavier buffers, FA BCG's, buffer springs and adjustable gas blocks is common place for carbine gas system 16"-20" barrels. An under gassed 30 caliber is very very frustrating to fine tune, believe me on that one.

You will notice that many 300 AAC and 7.62's long barrels are routinely fabricated with the majority Carbine and secondly Mid length GS. Even a few companies fabricate 16" - 18" in pistol length systems, however I would avoid these.
Click to expand...

When I was speccing out my 16 inch x39 upper, I asked for a mid-length gas system, as I thought it would be smoother. The builder, Steve Adelmann, of Citizen Arms, who is a former Delta god, counciled against it. His assertion was that, 7.62x39 didn't have the pressure to run reliably with a mid length system. I took him at his word and went with his recommendation. The upper came with 3 test groups using premium European ammo, that I don't know and can't pronounce the names of even if I did. All 3 groups were under 1 inch with the best being just over .75 inch. The rifle will reliably shoot Czech and Norcy surplus under 2 inchs at 100. My friends identical rifle, which was built at the same time, has shot a 2.75 inch group at 300 meters with Norcy surplus. The ammo isn't capable of that consistently, but you'd be surprised what chinese surplus is capable of given the right platform. The downside, the upper cost about 2/3rds of what my x39 XCR cost. You do get what you pay for.
 
teddy49 said:
When I was speccing out my 16 inch x39 upper, I asked for a mid-length gas system, as I thought it would be smoother. The builder, Steve Adelmann, of Citizen Arms, who is a former Delta god, counciled against it. His assertion was that, 7.62x39 didn't have the pressure to run reliably with a mid length system. I took him at his word and went with his recommendation. The upper came with 3 test groups using premium European ammo, that I don't know and can't pronounce the names of even if I did. All 3 groups were under 1 inch with the best being just over .75 inch. The rifle will reliably shoot Czech and Norcy surplus under 2 inchs at 100. My friends identical rifle, which was built at the same time, has shot a 2.75 inch group at 300 meters with Norcy surplus. The ammo isn't capable of that consistently, but you'd be surprised what chinese surplus is capable of given the right platform. The downside, the upper cost about 2/3rds of what my x39 XCR cost. You do get what you pay for.
Click to expand...

I would not argue against his recommendations. As he has pointed out that it is "more reliable" for all brands of ammo and you are also correct that a mid is smoother and less violent.

However it is more sensitive to the ammo you select and will not operate unless the proper gas port size is drilled. If you reload and find the optimum ammo configuration and it is dialed in generally a mid length is more pleasant to shoot. You can get a fine shooting and smooth rifle length 20" in barrel, however this requires a .125 gas port and is very very picky on the ammo setup. That setup is very problematic.
 
Last edited:
Sqr said:
You will notice that many 300 AAC and 7.62's long barrels are routinely fabricated with the majority Carbine and secondly Mid length GS. Even a few companies fabricate 16" - 18" in pistol length systems, however I would avoid these.
Click to expand...

In my hours long search, this is exactly what I found and same applies to both DI and piston. Piston however are scarce and can count the fabricators with one hand.
 
You must log in or register to reply here.
Back
Top Bottom