Cutting and Threading an AR barrel help

[Bako]

Newb question, first time on this particular discussion.

I have a 24 inch AR15 varmint barrel. It is stainless. I would like to cut it down to 18" and thread the end 1/2" x 28 TPI to receive a muzzle brake compensator.

Is this possible and if so, who does this kind of work?

Thanks.

[Fjold]

Yes, it's possible and fairly easy.

Talk to Randall, ie: ar15barrels

[xxdabroxx]

Newb question, first time on this particular discussion.

I have a 24 inch AR15 varmint barrel. It is stainless. I would like to cut it down to 18" and thread the end 1/2" x 28 TPI to receive a muzzle brake compensator.

Is this possible and if so, who does this kind of work?

Thanks.

what twist is it? If its a slow twist that may screw up shooting heavy bullets for you.

[stormy_clothing]

Yes, it possible and fairly easy.

Talk to Randall, ie: ar15barrels

ar15barrels.com he charges 70 bux for tear down cutting and threading and does an awesome job

[Bako]

Thanks folks.

I was thinking of a JP Enterprise tactical compensator. I guess I should buy it first and send it and the barrel to Randall. I think I also need a micrometer to measure the diameter of the bull barrel so it matches the compensator I order.

[gozuki]

I can help you with that. Pm me your phone #. I've done a few dozen for a couple manufacturers.

[gozuki]

I'm in Bako too...

[CRTguns]

what twist is it? If its a slow twist that may screw up shooting heavy bullets for you.

???


Slow twist don't shoot heavy bullets well anyway... The twist rate is given in how many inches for 360 degrees of rotation- not how many revolutions teh bullet makes in the barrel before leaving.


And- if you cut back to 18" you may have to open up gas port- std in 20 and 24" guns is .090"- you may have to go up another ten or fifteen thousanths.

[ar15barrels]

I think I also need a micrometer to measure the diameter of the bull barrel so it matches the compensator I order.

Your barrel should measure 0.920" forward of the gas block.
You will want the JP 5 series comp.
I would go with the 5/8-24 model simply because there's no good reason to thread for 1/2-28 when 5/8-24 is also an option.
This should be the one you want: http://www.jprifles.com/buy.php?item=JPTRE-5.58S.925
Send it along with the upper so I can index it to the barrel by machining rather than by shimming.

[Trapper]

The 5/8-24 has a .350 exit hole, wouldn't he want the 1/2-28 with the .270 exit?

http://www.jprifles.com/buy.php?item=JPTRE-5.12S.925

[fusionstar]

Turning down a bull .920 barrel down to thread 1/2"-28 isnt as good as 5/8"-24 Because of the extra metal that would have to be removed.

Also.. if you mess up threading 5/8"-24 you can always turn it down and thread it 1/2"-28

1/2"-28 is perfect for .750" barrels and is standard.

[CRTguns]

JP rifles... I can't figure out why they would not just leave the through bore small- so you could pick the caliber.

[Bako]

I called JP and discussed this thread. They advised against the 5/8 - 24 because of the bore issue. The tech I spoke with said the cutouts and the holes on top are designed specifically to work with the pressures released as the bullet goes through each hole of the caliber it was intended.

If you send a .223 bullet through a .308 hole, he said, there will be space around the bullet allowing gases to continue to move forward and diminish the effects of why you have the muzzle brake in the first place.

I will be ordering the 1/2 - 28 TPI because they don't sell the 5/8 variety in .223.