Help w/ 10.3 10.5 SBR...

[ACMcGaha]

*** see my earlier post... Inexpensive set that allows you to check gas port. ADCO just did a phenomenal job on the barrel I just sent them for 10.30" and .070 gas port. I highly recommend them, their door to my door in 7 days. Just curious, besides drilling, how would you adjust the port?


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[Ming_the_Merciless]

Does anyone have any leads on a 10.3-.5" barrel that has the smaller gas port I'm after?
Is my only solution to buy a longer barrel and have it cut down?
Can anyone chime in with their experience running 10.5 both suppressed and unsuppressed with a STANDARD gas block?

I run a 10.5" Noveske N4 light barrel with low profile gas block on my MK18 clone (not the stainless but chrome lined FN 249 barrel blank). I don't remember exactly what I mic'ed the gas port at prior to installing the block, but I think I pin gauged it to ~0.069". When I run mine suppressed, Surefire 762-RC, it hasn't caused any noteworthy issues that I'm aware of yet. A buddy of mine also has the same barrel, he Form 1 his own can, and it runs fine as well. Both of us running H2 buffers with Springco Tactical Spring Blue.

http://www.rainierarms.com/noveske-n...barrel-10-5-lp

The benefit is it comes with a pinned gas block, so you don't have to buy the pinning jigs, for the dimple or straight/taper cross pin. If you order direct, see if you can get them to send it without it pinned. As it can be a b!$#% to out.

Just curious, besides drilling, how would you adjust the port?

If you can't do it at the port, then the gas block can be regulated. There's a number of difficult aftermarket regulators, some requiring tools, some not. From factory, off the top of my head, I can name Noveske, LMT, and LaRue that have their own proprietary designs that comes in-house with their rifles.

[ACMcGaha]

Adjustable gas blocks only work if the gas port is large enough to allow the volume of gas that you are looking for - the upper limit if you will. That was in reference to sidewaysil80 saying he was surprised ADCO drilled barrels. I'm wondering how else the gas port could be enlarged.


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[Ming_the_Merciless]

Adjustable gas blocks only work if the gas port is large enough to allow the volume of gas that you are looking for - the upper limit if you will. That was in reference to sidewaysil80 saying he was surprised ADCO drilled barrels. I'm wondering how else the gas port could be enlarged.

I'm tracking with you - there's no other way to enlarge it. The only way, is what you did, take it to a competent smith that has a good mill with zero run out. Sort of off tangent, which reminds me of seeing something unique, an gas port drilled at an angle, in line with where the gas erosion starts.



But my google-fu is weak today, I can't remember where I've seen that before.

[ACMcGaha]

Interesting.


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[jerrysimons]

Anybody know the gas-port size of PSA's CHF 10.5" ?

[Robb Jensen]

A 10.5" LMT or Noveske 10.5" N4 barrel will have the correct barrel gas port of .071" , not sure where you found .070" info.

[Lincoln7]

Anybody know the gas-port size of PSA's CHF 10.5" ?

Mine measured out to approx .078" using drill bit and calipers. I installed an adjustable gas block on mine.

[jerrysimons]

Mine measured out to approx .078" using drill bit and calipers. I installed an adjustable gas block on mine.

Thanks. I guess there is just no replacement for a LMT 10.5 FSB upper.

Are not LMT barrels cryo treated? I don't think they are CHF.

[JG007]

So was there a recent post about LMT having a big port?

I called noveske, the guy was cool but said they cant give out port size. He did say the (10.5) N4 was correct mil spec size, and that the SS is not mil spec, (tighter chamber and larger port for reliability I presume?)

If I can verify the N4 size that could be good, Im also looking into the rainier