9MM Velocity in Pistol vs Rifle

[bobbob]

I know I can expect around 1200 FPS in a Beretta with a 115 grain bullet. If I put
that same bullet through a Kel-Tec Sub 2000 with an 18 inch barrel what might it bump
the velocity up to? Thanks

 

[BobsArmory]

This is just a rough guess but the 9mm was designed to run in a short pistol barrel so they use fast burning powders like Unique, Bullseye and W-231. The pressure curve peaks very quickly then drops off just as fast.

So I would think that if you are getting 1,200 FPS in a full sized pistol I would guesstimate that you would only see an additional 175 to 200 FPS gain in velocity in an 18" barrel since the pressure will drop off dramatically after the bullet travels 10" or 12" down the barrel.

See if you have a shooting range nearby that has a chronograph that you can use to verify. Or better yet, get one for yourself, they aren't that expensive. I would love to see the results!

 

[turbodieselfreak]

You'll have to chrony individual loads to be sure. One of the gun rags tested this very subject many years ago, and found that some cartridges actually lost velocity in a longer barrel. The powder charge was spent before the bullet exited the muzzle, and friction from the rifling caused the velocity to drop.

 

[Zoridog]

I went through a pistol caliber carbine phase many years ago. If my memory serves, standard velocity calibers picked up about 150 fps in carbine length barrels and magnums gained 500 fps. The bullets are designed to perform best at handgun velocity so it's a good thing that the 9mm gains "only" a couple hundred fps.

The great benefit of a carbine is accuracy. Offhand at 50 yards you can keep all rounds in the black. With a handgun I'm happy to hit the paper at that range.

 

[Pablo]

Originally Posted By: bobbob
I know I can expect around 1200 FPS in a Beretta with a 115 grain bullet. If I put
that same bullet through a Kel-Tec Sub 2000 with an 18 inch barrel what might it bump
the velocity up to? Thanks


Around 200-300, with +P 9mm pushing up to 400 extra FPS. Nothing to sneeze at. I love shooting +P from my 9mm and .45ACP carbines. I get this from one of my favorite sites: Velocity By the Inch

 

[Loobed]

I calculated about 1400 to 1450 fps.

You didn't say which model Beretta or the barrel length, so I figured it was a 92 with 5" barrel.

If your Beretta has a 4" barrel, than add another 30-50 fps.

 

[Loobed]

Originally Posted By: Zoridog


The great benefit of a carbine is accuracy. Offhand at 50 yards you can keep all rounds in the black. With a handgun I'm happy to hit the paper at that range.


Another benefit of a carbine shooting pistol ammo is the cost. Pistol ammo is cheaper than rifle ammo.

 

[bsmithwins]

Actual test results here: http://www.ballisticsbytheinch.com/9luger.html

Looks like you get ~200fps extra from most loads.

BSW

 

[2cool]

I studied the BBTI results carefully and the general conclusion I find is that if you have a short length/diameter ratio, such as automatic pistol rounds, you get less of a boost percentage wise vs. revolver rounds.
You can probably get more solid information on the Hi-Point or other carbine sites.
FWIW, the champ of getting a boost from a longer tube is a .357 magnum. The Lee 2nd edition lists a 125gr. XTP from an 8" barrel @ 1450 fps, and 2150 from an 18" barrel. The muzzle energy almost doubles!!!