Home AR-15 Ridiculous 4.5" 5.56 Barrel on AR15 Pistol First Shots (Shouldering Arm Brace...

Ridiculous 4.5" 5.56 Barrel on AR15 Pistol First Shots (Shouldering Arm Brace Now Illegal)

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Story behind 4.5″ Snub Nose AR Pistol

It’s a long story & you can find video on all the transformations this barrel has gone through to finally find its home.

The barrel started life as a 16″ 5.56 DPMS barrel on my first AR15. When I started my pistol/SBR project I was more into other calibers. I had converted my DPMS AR to 300 blackout & was using the DPMS barrel as a dedicated 22lr.

Then I decided to cut it down to 4.5″ & rethreaded it as a separate upper for my AR pistol. I used the CNC Warrior thread cut die to do it but it was a bitch because the thickness of the barrel was wider than the die. I marked the width I needed & then to an angle grinder to it. Its by far the ugliest thread job I’ve ever don but it’s got good threads & is concentric to the bore.

Then I decided to get the Taccom 17″ dedicated 22lr barrel which basically made the DPMS barrel obsolete. So this barrel just sat & sat & i felt so bad inside.

So about a month or so ago I decided that I was going to repurpose it. My current AR pistol had a 14.5″ barrel & I was going to put it on my clear rifle lower but it had to be pin & welded. I took that to the gunsmith & asked him about the AR gas system. With his info I decided to make my 4.5″ DPMS barrel semi auto instead of single shot.

I used the low profile gas block to measure where I needed to drill the gas port (3/32 drill bit) & used an old carbine gas tube. I cut down the gas tube exactly 1″ from the end of the barrel & had to bend it so it would properly align with the bcg. I also had to file the end of the gas tube to the same size & taper of the original end piece.

I had all the parts except an extra upper receiver & muzzle brake. After the first firing, I realized that I needed to remove access lube from the bcg firing pin & also install a Wolff extra power hammer spring. – 9/16/2014

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35 COMMENTS

  1. Hey you seem to respond to your videos. Do you have any idea where I could get my hands on a 6" upper receiver? I want soooo bad to get my hands on an AR pistol that fires 300 blackouts.

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