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1/25/2018 7:38:29 AM
Posted: 8/19/2003 5:15:06 PM EST
I wanting to know if there are any advantages to the mid length gas system offered buy Armalite and rock river arms.

is it more reliable?

are there any other advantages you gus can think of?

Link Posted: 8/19/2003 6:12:38 PM EST
[Last Edit: 8/19/2003 6:13:26 PM EST by SinistralRifleman]
Link Posted: 8/19/2003 6:26:50 PM EST
The PRI fatboy gas tube is a cheaper fix (assuming increasing the cyclic delay is the "fix" you're after) that will accomplish the same thing.
Link Posted: 8/19/2003 6:39:32 PM EST
I tried a PRI fatboy gastube in my M4 and it didn't have enough gas to cycle. I like a full length sight radius and want a short rifle so I am building a 16in DISSY carbine and plan to try it again. This time with a KAC low profile block and PRI front site and FF RAS. I think it will work great to smooth functioning and reduce pressure on the gas tube itself (my main concern as I am going to use a suppressor on it). I have read reviews where 280rds of fast suppressed fire have blown the tube on a 16in. I assume the PRI will last longer than that and I never expect to fire that much anyway but it will ease my worries reduce cyclic rate, smooth functioning, reduce blow back and fowling, etc. I like the idea of accomplishing the goal without going to an odd length gas tube that may be hard to find and replace (this way I need only carbine tubes for all my guns). Simplifying the number of critical spare parts. I really think a Bolt firing pin and gas tube are a pretty good kit for almost anything that can happen.
Link Posted: 8/19/2003 7:22:52 PM EST
Originally Posted By Green0: I tried a PRI fatboy gas tube in my M4 and it didn't have enough gas to cycle...
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I've heard this before, & it probably has to do w/ underpowered ammo. Increasing the size of the gas port might solve it. I've considered using the PRI in conjunction w/ increasing the gas port diameter to 0.091", see how that works. Troy industries sells bbl's that have a 0.091" port size option using a std gas tube, claiming that the increased size enhances reliability when the chamber gets really dirty, but how much more abuse/wear does the extractor take in prying expanded cases from the chamber under the faster cycling owed by the higher port pressures? I like the PRI's stainless steel construction over the std tube for increased durability of that material, but don't want its greater volume to cause under-functioning. I suspect there's a happy medium for the gas port size that'll keep the system reliable & still allow for increased gas dwell time. Of course, since you want an increased sight radius & parts commonality, the mid-length has got to be the way to go.
Link Posted: 8/19/2003 7:23:30 PM EST
I will ditto SinistralRifleman. To the addition that the mid lengths I have shot and as well info I have gleaned on midlengths is that they are much more reliable than the avg carbine. The MTBF for the midlengths is substantially upgraded - I myseld can only offer my experience, but it appears from what I have seen and peopel I talked with that it is mirrored in other users.
Link Posted: 8/19/2003 9:36:39 PM EST
can this advantage be accomplished with a pig tail gas system or the arm forte one that allows you to dial down the gas?
Link Posted: 8/19/2003 10:09:20 PM EST
Since I have only handled Bushmaster carbines, what exactly constitutes a midlength? How far forward is the gas port? Regards Cato
Link Posted: 8/19/2003 10:46:20 PM EST
Link Posted: 8/20/2003 1:12:38 AM EST
I have a mid-length RRA upper and it is very reliable and soft shooting, however, it is too heavy because RRA does not make std weight barrel. On the quest of getting an light weight upper with longer site radius in a 16", I've been trying to procure a new barrel from DPMS, it is an A2 profile 16" with the full length gas system. So far, no luck getting it even though it is listed in their catalogue[:(!]
Link Posted: 8/20/2003 4:17:15 AM EST
So when do you say that the midlength 1-7twist chromelined barrels were coming out?
Link Posted: 8/20/2003 5:07:20 AM EST
The recent SOF article, dealing with mid-lengths and the Surefire can, mentioned that there were M4 type feed ramp cuts in the Armalite upper. It also mentioned that the upper was "Mil-Spec". Can we assume that the chamber is 5.56, the twist rate is 1/7 and the barrel is chrome lined? Aside from the SIR #58 and the PRI handguard, are any other manufacturers offering, or definately planning to offer, M1913 railed handguard systems? Thanks. Regards, Jim
Link Posted: 8/20/2003 5:53:50 AM EST
Marty at Daniel Defense is working on a true mid-legnth FF Railed system.
Link Posted: 8/20/2003 11:19:15 AM EST
I run a Bushmaster 14.5" 1/7 M4 barrel with a PRI Fat boy without a hitch. The recoil push does seem a little softer than a regular 16" upper of mine. I have only put Federal XM193 and Winchester white box bulk from Walmart through it. I'm thinking about buliding a Dissapator upper soon, so let us know what works and what doesn't.
Link Posted: 8/23/2003 11:04:37 PM EST
will a pig tail gas tube do the same thing?
Link Posted: 8/24/2003 1:45:47 AM EST
I would think so Grinch. the pigtail would give you the same length gas tube as a standard 20" barreled gas tube. Heck, I've heard of several guys who have used an adjustable gas tube to accomplish the same task. I can't find any logical reason why either method shouldn't....
Link Posted: 8/24/2003 5:58:28 PM EST
If we are talking alternative methods... Handloaders can use faster or slower powders to tweak the pressure timing. Just one of the many advantages to handloading.
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