Ideal gas port size for 12.5" barrel ?

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[ARCHIVED THREAD] - Ideal gas port size for 12.5" barrel ?

Posted: 9/18/2009 5:54:06 AM EDT

Based on experience does there seem to be an ideally dimension for gas port diameter on a 12.5" barrel?

This is asked from the perspective of cutting down a 14.5" MRP barrel to 12.5"

From other posts I have gleaned gas-port "spec" to be:
10.5" .093"
11.5" .081"
14" .063"
16" .063"

Inference says an ideal gas port size for 12.5 may be somewhere around .070" or so?

Thanks for any inputl

Posted: 9/18/2009 8:32:51 AM EDT

[#1]

I just finished cutting a 20' Bushmaster bbl. down to 11.5

I started at 0.59 and ended up at 0.70. The bolt would activate the mag catch with military m193 @ 66.5

@ 0.70, federal 223E had enough umph to lock the bolt on an empty mag

Posted: 9/18/2009 8:50:21 AM EDT

[#2]

Quoted:
I just finished cutting a 20' Bushmaster bbl. down to 11.5

I started at 0.59 and ended up at 0.70. The bolt would activate the mag catch with military m193 @ 66.5

@ 0.70, federal 223E had enough umph to lock the bolt on an empty mag

What happens when you have to shoot substandard ammo? Rifle fails?

"Ill never run steel cased ammo" may not hold water when SHTF.

Posted: 9/18/2009 1:22:40 PM EDT

[#3]

I'm just giving him some input.

The gun is working well with the lightest ammo I have in the shop. Besides, I live in America where ts NEVER hits the f.

Posted: 9/18/2009 4:40:04 PM EDT

[#4]

I built my 10.3 barrel..

I started at 0.070 but with a full bolt carrier it was not enough to lock the bolt back on an emply mag... I finished using 0.082" and it works fine, with a Mc farland gas ring, and using good quality ammo..

I kept a sporter cut bolt carrier to use with crap ammo..

Posted: 9/18/2009 4:49:32 PM EDT

[#5]

Anywhere from .078-.081.

Posted: 9/19/2009 5:23:59 AM EDT

[#6]

Based on input looks like a .080 gas port and then variable buffers (H or H2) should produce a
weapon reliable on various types of ammunition.

Thanks for the input.

[ARCHIVED THREAD] - Ideal gas port size for 12.5" barrel ?

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