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3/21/2007 8:37:52 PM EDT
Hello, I'm  FNG to this site, but have to say I like it. My first question is how much barrel is required in front of the gas block for proper function on a rifle lenght gas system? What I mean is can I cut 2 inchs off my 20" NM barrel and have it still function alright. Then are there any legal issues in having it retreaded so I can put a Smith Vortex on the end. Thanks and nice to be here.
3/21/2007 8:41:01 PM EDT
[#1]
17 inches or more, if you resize the gas port. 18 or more if you dont.
3/21/2007 10:26:29 PM EDT
[#2]
As long as you dont go under 16" your legal.
3/21/2007 10:38:02 PM EDT
[#3]
Except they have functioning issues that short.
3/22/2007 8:13:15 PM EDT
[#4]

Quoted:
Hello, I'm  FNG to this site, but have to say I like it. My first question is how much barrel is required in front of the gas block for proper function on a rifle lenght gas system?


Stay with at least 5" out there and all is well.

I open up gas ports as required when shortening to 17" or 18"
I recommend against 16" long barrels on the rifle length gas system.
3/22/2007 8:30:58 PM EDT
[#5]
Randall, one of these days you nede to explain to us exactly how a suppressor affects dwell time.  It would be interesting to see how a 16 inch barrel with an OPS 14th would work if the gas port was rifle length.
3/22/2007 8:39:03 PM EDT
[#6]
Thanks Randell, If I have it shortened to 18 " how much does the gas port need to be opened. I have a 20" RRA NM barrel. My intent is to shorten the barrel to 18", put a Vltor gas block on it and a rifle lenght 4 rail free float forearm.
3/22/2007 8:45:25 PM EDT
[#7]

Quoted:
Thanks Randell, If I have it shortened to 18 " how much does the gas port need to be opened. I have a 20" RRA NM barrel. My intent is to shorten the barrel to 18", put a Vltor gas block on it and a rifle lenght 4 rail free float forearm.


I would have Randal do the work you wont be disapointed.
3/22/2007 8:56:56 PM EDT
[#8]

Quoted:
Randall, one of these days you nede to explain to us exactly how a suppressor affects dwell time.  It would be interesting to see how a 16 inch barrel with an OPS 14th would work if the gas port was rifle length.


I don't have any practical experience with suppressors so I can't offer first hand knowledge.
I HAVE talked to Denny (GTS) about this and he has EXTENSIVE suppressor and machine gun experience going back a LONG time before AR15's even got mainstream popular.
Denny tells me (and I believe) that the length of the suppressor that's added to the barrel almost directly equates to adding the same amount of bore length to the barrel.
Now in the case of reflex designs, you gain more barrel length without as much actual measured length.
So, the longer the can, the more effective barrel length past the port.
Putting a can on a 16" barrel with rifle gas should make it run just fine.
3/22/2007 9:09:08 PM EDT
[#9]

Quoted:
Thanks Randell, If I have it shortened to 18 " how much does the gas port need to be opened. I have a 20" RRA NM barrel. My intent is to shorten the barrel to 18", put a Vltor gas block on it and a rifle lenght 4 rail free float forearm.


Since nobody else noticed that you started this thread with your post #1, I'll be the first to say "welcome"...

You may or may not know that I specialize in barrel and upper work.
That being the case, I can handle all of this for you.
I keep PRI gas blocks in stock which are almost identical to Vltor gas blocks, especially if you are going to cover them with an extended handguard system such as a LaRue 13.2 which I also have in-stock.

Pricing is listed on my shop services page.
Parts can be found on my parts page.

You might not have found it yet, but check out my how it works thread that's tacked in the troubleshooting section.
3/22/2007 11:26:48 PM EDT
[#10]
randall does excellent work i know this because i have had him do work for me before. if you are thinking about shortening your barrel ship it off to randall you will not be dissapointed.
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