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ChicagoTex, nice explanation.
Why, thank you.ChicagoTex, nice explanation.
my rifle gas 16" .. has gas port of .110
runs everything i feed it .. reliably and smoothly.
i like it alot.
i started this life with nothing.....kept most of it.
I've played around with gas port size and location quite a bit... you can get a 16" with Rifle Length system to run... but as I recall, all of the test guns were single shots when we froze them.
Short story is we did not spend a lot of time on the concept, because the 16" with Mid-Length will always be a better solution.
Please let me know if I have offended you...
I would like to move on to my next task.
I provide legal consultation and training - specializing in the Law of Gravity.
As for port size, location, dwell and all of that... seems a lot of folks don't get the "big picture"
The only real important pressure is the max/operating pressure inside of the BCG - that pressure is a function of the following:
Gas Pressure at the port
Port Size
Barrel diameter
Time the pressure stays high (dwell)
Lock Time - the time the BCG remains locked, while pressure is allowed to build
Changing any on of these will change the pressure in the BCG - and of course, changing any one of these will most likely mean one or more of the others needs to be changed to compensate.
Please let me know if I have offended you...
I would like to move on to my next task.
I provide legal consultation and training - specializing in the Law of Gravity.
Neither of the 20" M16A2-profile Colt barrels I had cut down to 16.1", crowned and rethreaded ran well with anything less than MX193/XM855 power 5.56mm. They also stopped running when they got a little dirty, the additional friction was too much. I'd clean it, it would run another 2-300 rounds, and then start short stroking. I had my gunsmith open up the gas ports to .105, and they cycled a bit more violently than I liked, and still didn't like Wolf ammo. Even then, the gun didn't like any USGI mags with anything less than full power, new springs. This was about 9 years ago, better mags weren't an option at pre-2004-sunset prices, and PMAGS were still in the future. Eventually, I just sold both barrels off with disclaimers.
I wouldn't do it again, it seemed there was no margin for error for weak mag or extractor springs, worn parts, filthy or dry internal conditions ...the gun only worked under ideal circumstances. It was a way to use a barrel I had gotten for cheap - even then, 20" barrels were not as in-demand- and was free to have cut down, as I worked with a gunsmith's shop on site.
I've used mid-length gas with 14.5" and 16" barrels with great success, and rifle gas with 18" and 20" barrels with similar success. I now have a 16" "Dissipator" clone from PSA, with mid-length gas tube under rifle length MOE handguards out to a FSB. It scratches my weird itch to own a 16" that looks like a cut down 20", and works as well as any other 16" Middy I own. Best of all possible worlds.
Well, it's 16" and rifle length gas .... but it's 308.
KAC SR-25 ECC
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By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest. - Confucius
I'm pretty sure Delton makes one of these barrels that you are looking for, however I agree with the above poster that you won't have proper dwell and will have an oversized gas port. Better in my opinion to go 16" with a mid length.
-Thomas
Member, ISRA; Life Member, NRA; USCCA Certified Instructor; NRA Certified Instructor, AGI Certified Gunsmith, Illinois Concealed Carry Instructor
www.alphakoncepts.com www.gunrights4illinois.com
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