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6/13/2008 9:07:00 AM EDT
I need the correct Gas Port Diameters for various barrel lenghts

example;
20in barrel rifle length gas system = .000in dia gas port
18in barrel rifle length gas system = .000in dia gas port

14.5in barrel carbine length gas system = .000in dia gas port
10.5in barrel carbine length gas system = .000in dia gas port

I know this information has been posted in the past I just can not seem to find it and yes I tried the search. Currently my time on the internet is very limited and so I am asking for a helping hand.

Thanks in advance for your reply
6/13/2008 4:17:03 PM EDT
[#1]
I don't think every 16" barrel has the same diameter gas port.  It varies between manufactures.  ie. Bushmaster gas ports are larger than LMT as LMT was design more around shooting full power 556 ammo.
6/13/2008 5:23:28 PM EDT
[#2]
Barrel diameter at the port plays as well. Md. ar15 site has a chart.
6/14/2008 9:14:10 AM EDT
[#3]
I did could not find the information on the Maryland site.
What I really need to know is when working with barrels of .750 diameter at the port. How big of a hole must be drilled when going from a 14.5in to 10.5 inches barrel and starting with a standard 20in rifle barrel the diameter to drill the gas port after cutting the barrel to 18 inches.
Any help would be greatly appreciated
Thanks again

6/14/2008 6:33:17 PM EDT
[#4]
Maintenance faq. That is where a chart with this info. is at. Go back to the MD. site and its there. I tried to cut, paste, would not work for me-
6/14/2008 8:21:59 PM EDT
[#5]

Quoted:
I don't think every 16" barrel has the same diameter gas port.  It varies between manufactures.  ie. Bushmaster gas ports are larger than LMT as LMT was design more around shooting full power 556 ammo.

Documentation please?
6/15/2008 11:26:33 PM EDT
[#6]
Twist rate plays a part in gas port size as well.
6/16/2008 5:34:07 AM EDT
[#7]
Barrel Length (in) Barrel Diameter (in) Distance from Muzzle (in) Min Port Size (in) Max Port Size (in)
11.5 .625 3.850 .081 .089
11.5 .750 3.850 .086 .094
14.5 .625 8.375 .063 .078
14.5 .750 8.375 .070 .086
16 .625 8.375 .063 .078
16 .750 8.375 .070 .086
20 .625 6.875 .086 .093
20 .750 6.875 .093 .096
24 .825 N/A .089 .089


These were posted here a few years back.
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