.750 from block to muzzle?

[HSNARC]

Are you guys aware of any higher end "hard use" barrels which have a profile similar to an M4, but have a .750 diameter barrel for the gas block and then another section the same diameter further out (preferably until the muzzle threads) so an A2 style front sight post can be pinned as close to the muzzle as possible while still maintaining the correct spacing for rifle length 2 piece hand-guards? Ideally it would be a 14.5 (pinned and welded) or 16 inch barrel with a pinned low profile gas block at the intermediate location and then the A2 out front for a nice long sight radius/hand-guard real estate.

I really like the idea of properly drilled and pinned gas blocks, never had issues with alignment or gas leaking from one. Not the story with the set screw models. I realize that stripped ar barrels seldom come pinned, and thats not an issue because it should be an easy task for a good smith. I just want a good quality chrome lined barrel in the proper length and profile for it to work.

 

[kl3309]

Google "dissapator barrel"

 

[...]

Google "dissapator barrel"

yup, i would recommend getting an actual "dissipator" over a mock-dissy....they are super light recoiling.

Del-Ton, Inc. AR-15 16'' Dissipator Rifle Kit

Del-Ton, Inc AR-15 AR15 16' Dissipator Rifle Kit. AR15 AR-15 16' dissipator rifle kit includes upper receiver, barrel, handguards, buttstock and lower parts kit. Completly assembled upper assembly has been test fired and head spaced.

www.del-ton.com

 

[PBWalsh]

Doesn’t a full rifle length gas tube on a 16” barrel lead to cyclic and dwell time issues?

 

[HSNARC]

yup, i would recommend getting an actual "dissipator" over a mock-dissy....they are super light recoiling.

Doesn’t a full rifle length gas tube on a 16” barrel lead to cyclic and dwell time issues?

This. I cant imagine that 1-2" of dwell time to be adequate for a duty rifle.

 

[RyanScott]

Doesn’t a full rifle length gas tube on a 16” barrel lead to cyclic and dwell time issues?

It can, and such a setup would only be acceptable in warm weather with hot ammunition—and even then, not for duty. An extra inch or two makes a big difference. That said, it’s a brilliant setup if you use it 100% suppressed, with a custom small porter barrel.

 

[...]

Doesn’t a full rifle length gas tube on a 16” barrel lead to cyclic and dwell time issues?

The only issues ive had with mine is with lower pressure ammo like wolf or Tula occasionally not cycling

M855 and m193 run 100%

 

[PBWalsh]

Is it a matter of properly cut gas hole size or time the bullet is in the barrel after passing the gas hole?

If its the former, surely someone could figure out a properly spec’d hole size to accommodate a rifle length, 16” barrel.

 

[RyanScott]

The proper size is .1” or up to .11” if you like cheap ammo. That’s not the problem. The problem is that with short dwell time it becomes finicky depending on weather and ammunition. A friend shoots a 15” rifle gas upper a lot. He’s in a swamp in Texas. If you took that to where I live and shot during the winter, you’d have trouble.

But, add a short can and 16/rifle is brilliant.

 

[...]

Is it a matter of properly cut gas hole size or time the bullet is in the barrel after passing the gas hole?

If its the former, surely someone could figure out a properly spec’d hole size to accommodate a rifle length, 16” barrel.

i think its a little of both, the short dwell time isnt helping anything, and there is only so large you can reasonably cut the gas hole....

that being said, for the most part, the Delton dissy runs great with warmer ammo.

you can also get a mock dissy with a carbine or midlength gas tube for greater reliability

https://palmettostatearmory.com/psa-16-mid-length-5-56-nato-1-7-nitride-dissipator-upper-black-no-bcg-or-ch-5165449779.html