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Old July 01, 2018, 09:33   #1
Gazz
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Making a Pistol Barrel from a Rifle Barrel?

I was given a takeoff barrel from an AR by a police department armorer. It showed some roughness just forward the gas vent and I guess that was why it was replaced. I tried it on a build and it is all over the place on the target - 12" groups at 50 yards. So now I'm wondering if it could be shortened to remove the rough part which would put the gas port about 2" (or maybe less) from the muzzle. I wonder if I would have to open up the gas port or even move it back a bit. Anybody have any experience with something like this?
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Old July 01, 2018, 09:53   #2
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Ar barrels are so cheap, I'm not sure why go to the expense unless you have a lathe to do the work.
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Old July 01, 2018, 10:08   #3
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The expense would be buying a new barrel. I do have a lathe and cutting and threading would take me no more than 45 minutes and I will probably just do it. My question was has anybody else done this and what were their experiences with the gas port location.
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Old July 01, 2018, 10:20   #4
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What is the length of the barrel and what gas system is it drilled for? What profile does it have?

You might fix its problem by simply recrowning the muzzle.
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Old July 01, 2018, 10:57   #5
Gazz
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It is a 20" Colt pencil barrel. Looking at it closer, the roughness begins just in front of the gas port so maybe moving the gas port would be required. When I say roughness I am talking about no or barely evident rifling that goes to about the muzzle. I don't think crowning would help.
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Old July 01, 2018, 11:04   #6
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Quote:
Originally Posted by Gazz View Post
It is a 20" Colt pencil barrel. Looking at it closer, the roughness begins just in front of the gas port so maybe moving the gas port would be required. When I say roughness I am talking about no or barely evident rifling that goes to about the muzzle. I don't think crowning would help.
I think pencil barrel will be too small diameter at the gas block journal.
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Old July 01, 2018, 11:31   #7
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If moving the gas port is required and it is looking like that is what will need to be done, the barrel diameter gets large enough (.625") about 2" behind the existing gas port. I guess its the Yankee in me that does not want to scrap something that could be used.
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Old July 01, 2018, 11:34   #8
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If have enough meat on barrel and turning a new gas block journal is not an issue would weld up gas port, cut, crown and move gas port back. Gas port two inches from muzzle and dwell time of projectile in barrel after passing port will possibly force you to open port and run gun overgassed. Have been given over a dozen barrels and cut, welded, crowned and more but some just went in a pile that will never be used unless build a non functioning display model.

Have you considered lapping bore to smooth up area of roughness? Several ways to skin this cat from pulling an abrasive lap through by hand or using something like Tubbs lapping rounds of different grits to smooth bore without chopping. Google "hand lapping" and "fire lapping" then maybe give one a try.

http://www.rifleshootermag.com/gunsm...g_finish_0723/
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Old July 01, 2018, 14:46   #9
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https://www.ar15.com/forums/ar-15/Is...__/123-550259/
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