How much of an increase in velocity would I see moving from a 20" barrel to a 22" barrel in a rifle?

Question

I'm thinking of this in a project with the 7.62 x 39 caliber. I will be shooting standard factory loads. I may use Winchester as they seem to be the most available in name brand.

Answer 1

shooting the same round in each barrel you will not notice a signifigant change in velocity. There has been a long held belief that a longer barrel means more accuracy, but that is not 100% true either, there have been several articles in several shooting magazines over the last several years that have debunked that myth pretty well. The only way you might see a signifcant change in velocity is if you have a really hot load that isn't getting a chance to burn most of the powder before the bullet leaves the barrel. Since it is 7.62x39 and you said you are using factory loads that generally will not be an issue. Using a particular brand just because there is more of it on the shelf is not a reason to buy it, neither is velocity, shoot a 5 shot group with several available brands and use what is the most accurate for your rifle. If you are loading for 7.62x39 which most people don't even bother with in that cal. then I would just work your load so you are getting the most accurate round you can get, don't get hung up on velocity, a faster bullet does not mean more accurate bullet.

Answer 2

Nothing wrong with Wolf in that caliber and they'll save you a ton of $.

Lots of semi-correct answers to this question. This round will not burn completely in either a 20 or 22 inch barrel, just look at the muzzle flash to confirm that, so you will gain some. How much will be determined by the comparative condition and quality of the barrels, the weight of the bullets, etc -- assuming both barrels are similar in internal construction.

Given similar quality, accuracy between a 20 and 22 inch barrel will increase more than you will typically see in a switch between 26 and 30 inch barrels, so expect a small improvement.

Only down side is slight weight increase and slight decrease in mobility. I like distance shooting, so I would make the change. Still, if distance is your objective, consider stepping up to 7.62 X 54R or go all the way to 50 bmg. I love making holes a mile away, but I only get to shoot the dang thing once a year because I don't have a place of my own, or in my part of Texas, where you can even see a mile away.

Have fun with the AK?

Answer 3

The 7.62x39 is a low pressure cartridge so the extra 2" of barrel will only add about 40fps which is not worth the cost of a new barrel.

Your better off spending the money on more ammo.

Answer 4

a lot of crap answers about barrel twist and other things that have nothing to do with it.

Henry S gave about the best answer.
About 40fps difference and probably not worth the price of the barrel.

Answer 5

It really comes down to twist how fast the rifling rotates the bullet. A long barrel with a slow twist will be the same as a short barrel with a fast twist.

Answer 6

It wont do a thing for velocity, it will however give you just that 2 extra inches and a little better accuracy. The only thing that will give you more velocity would be to try to hand make "hot" loads. Unless you are experienced and know what you are doing or a good learner, I wouldn't suggest making home-made "hot" loads. If not done right, hot loads will mess up your firearm, injure you, kill you, or all of the above.

My best advice is to consult a professional gunsmith at your local gun store. They will be able to give you the proper assistance you need and it will be done correctly if not perfectly.

Good Luck.

Answer 7

Maybe less than 100 fps.

Answer 8

Nothing to be gained by doing that*... Forget about it*...Waste of time and money*...