Optimal Barrel Length for the 7.62X39
- Thread starter Ryu
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TooTaxed
Member
Interesting question...I don't know the answer, but for range shooting I much prefer the SKS, with it's longer barrel and sight radius, to the AK. 
natedog
Member
16" or 20" are both fine. I don't think the 7.62x39mm round gains all that much from extra barrel length; I believe the RPK (24" barrel) only has about 100FPS over the 16"- definetly not enough to justify 8" more barrel. I like the 16" barreled AKs and Para-SKS. Sight radius is shorter, but hey, these aren't match rifles in the first place.
As far as accuracy goes, barrel length does not directly affect that.
The quality of the barrel does make a big difference.
A rigid receiver also helps.
For velocity, I think the military 7.62x39 ammo is optimised for a 16" barrel.
You may get more out of a longer barrel, but not a whole lot more.
I also think it is possible to reload for much better performance.
The quality of the barrel does make a big difference.
A rigid receiver also helps.
For velocity, I think the military 7.62x39 ammo is optimised for a 16" barrel.
You may get more out of a longer barrel, but not a whole lot more.
I also think it is possible to reload for much better performance.
"As far as accuracy goes, barrel length does not directly affect that."
I'm not sure I agree with that statement. I mean an AR with an 8" barrel is not as accurate as one with a 20" barrel. I can see it not changing to accuracy out to a set distance as an 8" AR may be every bit as accurate as the 20" out to 100 yards but I don't think that would remain true out to 400 yards. But I'm no expert.
I guess I'll have it cut down to 16" and have a great little carbine.
I'm not sure I agree with that statement. I mean an AR with an 8" barrel is not as accurate as one with a 20" barrel. I can see it not changing to accuracy out to a set distance as an 8" AR may be every bit as accurate as the 20" out to 100 yards but I don't think that would remain true out to 400 yards. But I'm no expert.
I guess I'll have it cut down to 16" and have a great little carbine.
Feanaro
Member
Ryu: I think you are talking about bullet drop, something normally left out of accuracy concerns. Can the rifle make the same sized groups, no matter whether you have to aim to inches or two feet high at XYZ yards, with different size barrels? All other things being equal, the groups should be the same. Or so I would think.
Owen
Moderator Emeritus
The barrel length is not very important for the accuracy of the rifle. The barrel length becomes an issue when you start losing sight radius. If you are using optics, no sight radius is lost with a short barrel.
A rigid receiver, the quaity of the barrel, and the quality of the ammunition are all much more important than the length.
Case in point, the bench rest guys are generally using 16-18" barrels now.
A rigid receiver, the quaity of the barrel, and the quality of the ammunition are all much more important than the length.
Case in point, the bench rest guys are generally using 16-18" barrels now.
DMK
Member
Another point to consider regarding barrel length and accuracy is sight radius. An 8" AR barrel has a *much* shorter distance between sights than a 20" AR barrel. Some competition rifles have an extra length of over bored tube attached to the end of their barrels just to extend that sight radius.
If you are talking scoped rifles, then a slightly shorter barrel of the same diameter is stiffer than a longer barrel and may actually be more accurate with all other variables equal.
Of course when you are getting down to 8" barrels in a rifle caliber, you are leaving a lot of powder to burn after the bullet has left the muzzle, which means lower velocities than that caliber is designed to be operated at and that can probably do some odd things.
Personally, I always wondered what the difference in velocity was between a 16" AK and a 20" SKS. I have a gut feeling that 7.62x39 is slowing down in an RPK barrel after 20" but I can't find any hard data anywhere.
If you are talking scoped rifles, then a slightly shorter barrel of the same diameter is stiffer than a longer barrel and may actually be more accurate with all other variables equal.
Of course when you are getting down to 8" barrels in a rifle caliber, you are leaving a lot of powder to burn after the bullet has left the muzzle, which means lower velocities than that caliber is designed to be operated at and that can probably do some odd things.
Yea, you'll be fine around 16" to 18". I'm not sure whether you are talking about a bolt action or AK/SKS, but I think the biggest problem with the AK and SKS is sight radius. If you could move that rear sight back 3"-4", it makes a big difference. Case in point: The Tech-Sights rear sight upgrade for the SKS. It made a huge difference for me and others have said the same thing here.
Personally, I always wondered what the difference in velocity was between a 16" AK and a 20" SKS. I have a gut feeling that 7.62x39 is slowing down in an RPK barrel after 20" but I can't find any hard data anywhere.
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