10.3" gas port size please

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11-02-2016, 16:32
Robb

10.3" gas port size please

Long story is the kid got his tax stamp for a SBR, so we're having a COLT 16" barrel cut down to 10.3".
This is for 5.56/223, not suppressed AT THIS TIME. A can MAY be in the future depending on how life goes. The barrel will retain the fixed Colt factory front sight.
Son does not care to run an adjustable gas block, he likes the look of the standard front sight.
Ive read the diameters for gas ports run from .070 with .083 being used by Daniel Defense and .093 by Colt.

Again, Someday we may want to get a can, but for now it will be shot unsuppressed.

The smith I took it to asked me what gas port I wanted, didn't know what to say. He recommended .0925 (I think that's what he said).

What would you folks recommend?
Thanks,
Robb
11-02-2016, 16:37
kwando

http://www.gandrtactical.com/cgi-bin...on&key=SP64049

Stock colt 10.3" is .070
11-02-2016, 16:55
Robb

Okay, I read .093 earlier, I guess we'll go with .070.
11-10-2016, 17:32
gat_wrench

.076, and get an adjustable gas block. .076 is a bit over-gassed with a standard block but will run most ammo. DD's "mk18" ports are .08- something, and they're a bit hot in my opinion. .069-.070 works great with a can, but not always w/out. May want to run an H1 or an H2 buffer
11-10-2016, 18:05
XXFattyHunterXX

I have a factory non-cut down DD 10.3 barrel .070 port, their mk12 gas block, Wolff XP spring and Spikes T2 buffer. Works every time suppressed or non-suppressed.
Until Geissele SD-3G, shooting PMC bronze 223, trigger won't reset, Perfecta and all 5.56 no problem.
11-11-2016, 21:30
Robb

We went with a .070, I'll keep the buffer weights in mind in case we run into relialibility issues
11-11-2016, 21:41
SA Friday

Quote:

Originally Posted by Robb

We went with a .070, I'll keep the buffer weights in mind in case we run into relialibility issues

.070, H2 buffer, Tubbs flat wire spring.
or
.070, H buffer, Tubbs spring, adjustable gas key BCG
or
.070, carbine or H buffer, Tubbs spring, adjustable gas block

.070 is a little bigger than what it should be, but with such a short dwell time on a 10.5" barrel it needs more punch up front to make it consistently work with anemic ammo (PMC 223) all the way to 5.56 ammo. Every time I see someone go too small on the gas port on a 10.3/10.5", it becomes a short stroke nightmare. LMT's are notorious for this. Have them stay in this size range initially. If needed, it can always have the A-fram removed and the port honed out a tad more to get the timing right. Can't put metal back in that gas port though.
11-13-2016, 19:11
jerrymrc

Quote:

Originally Posted by SA Friday

Can't put metal back in that gas port though.

This. Always can go bigger, little more difficult to go smaller. [Beer]
11-13-2016, 19:27
Great-Kazoo

Quote:

Originally Posted by jerrymrc

This. Always can go bigger, little more difficult to go smaller. [Beer]

Wait till you hit 60+