Cutting a barrel

[electronman1729]

Have question about cutting a barrel. Can someone explain the difference in ballistic performance between a factory made say 12"(or what ever length) 1:7 twist barrel compared to a 12" that was cut from a 20" barrel with a 1:7 twist? Looking a doing another SBR, and finding the proper barrel has been difficult.
What difference in MOA would i see from a factory made short barrel vs a cut barrel of the same length?

[ray1970]

Going to depend on the quality of the original barrel but most likely you might actually see an improvement in accuracy since the barrel will get a new crown. Also, if it is a chrome lined barrel it probably isn't a good idea to cut it down as the chrome lining will most likely chip or flake where it is cut.

[ray1970]

What kind of barrel are you looking for? I haven't had trouble finding anything lately.

[electronman1729]

A 13" Barrel for a Galil SAR

[ray1970]

A 13" Barrel for a Galil SAR

Lol. Yeah, I noticed your other thread right after I asked.

That one might be a little tricky.

[electronman1729]

Lol. Yeah, I noticed your other thread right after I asked.

That one might be a little tricky.

Pic with the 16" barrel. (this is not mine, but another build from another forum)
The barrel which is 16" has a lame "condom" over the barrel to make it look cool

[sportbikeco]

http://www.ballisticsbytheinch.com/223rifle.html

Great website.

If I were in the position you are on that I would do one of two things.

1-Have my original chrome lined barrel cut down by someone who knew what they were doing and see how it worked. Im guessing in your application it would be just fine.

2-Buy a non chrome lined barrel and have it cut down. Do this if you can sell your original barrel to recoup money.

[Great-Kazoo]

Check with ak builder or apex for one.
http://www.apexgunparts.com/galil/im...compliant.html

http://armsofamerica.com/factorynewi...562238999.aspx

http://www.keepshooting.com/imi-fact...il-barrel.html



here's a real old add for one
http://www.copesdistributing.com/gal...el-p-3112.html

[BPTactical]

A general rule of thumb is your going lose about 100 FPS per inch removed relative to your starting length.
Something to consider- knocking an inch or two off of the average barrel should not be too big of an issue. When you start lopping off 6 inches or so you can run into excessive runout relative to the OD of the barrel. This is due to the dynamics of deep hole drilling, typically your bore will be closest to concentric at the ends. I have cut barrels back pretty far and had a couple end up looking like the wheels on a clown car, they were that eccentric.
Another consideration- if the bore is a chrome bore typically the bore is slightly oversized to compensate for the thickness of the chrome plating. When the bore is plated you will get a slightly heavier deposit of chrome near the muzzle and the chamber. Theoretically, you cut it back beyond that heavier deposit and you could be back far enough to be dealing with a slightly looser bore which will not help accuracy.
Just a couple of thoughts to ponder.

[SideShow Bob]

Another problem with cutting a 20" AR barrel down to a 12" one is that the gas port would need re-drilled as you would be cutting the existing one off. Also, the location for the new gas port would most likely need Milled to fit a gas block.
Of all the work involved, you could get a big name barrel of the desired size for the same or less cost.