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View Full Version : Help clarify carbine vs. mid length vs. ext. mid and rifle length gas systems


Falstaff
05-17-2011, 11:06 AM
I am putting together a new rifle based on a nice stainless .223 wylde barrel. I want to order the Vltor VIS integral upper/handguard but there are several choices. Carbine, mid, extended mid and rifle length. I'm not sure if I have a carbine or mid length gas system.The distance from the barrel extension to the collar machined into the barrel for the sight base or gas block is just under 10" (9 7/8" actually).

If I measure from the collar that butts up to the threads of the upper I get around 8 7/8"

What does an "extended mid" carbine measure? Is it just an extended handguard over the gas block (for the "dissipator" look?)or is it an actual slightly longer gas system?

cmace22
05-17-2011, 11:55 AM
Carbine uses 7"
Mid uses 9"
Rifle uses 12"

Measured from Barrel nut face on extension to rear of FSB.

Looks like you have a mid. Although you could just call the manufacturer or look at the website.

If you want to cover the GB use an extended mid. If not a mid will leave the GB exposes.

tacticalcity
05-17-2011, 11:57 AM
Looks answered to me.

451040
05-17-2011, 11:57 AM
carbine vs. mid length vs. ext. mid and rifle length

Those are describing the length of the rail on the Vltor Vis:

VIS-1 - standard carbine 7"
http://www.brownells.com/userdocs/skus/p_100004949_1.jpg

VIS-2 - standard midlength 9"
http://www.brownells.com/userdocs/skus/p_100004950_1.jpg

VIS -2A - extended midlength 10"
http://www.brownells.com/userdocs/skus/p_100004947_1.jpg
the 2A covers the gas block of a mid length system
http://www.bravocompanyusa.com/v/vspfiles/photos/BCM-URG-16MD%20BFH%20VIS10-2.jpg

VIS-3 - standard rifle 12"
http://www.brownells.com/userdocs/skus/p_100004948_1.jpg
the 3 extends 2" past the gas block of a mid length system
http://www.bravocompanyusa.com/v/vspfiles/photos/BCM-URG-16MD%20SS410%20VIS12%20IBB-2.jpg

Falstaff
05-17-2011, 12:41 PM
Thanks for the info, an extended mid will be my choice.

cmace22
05-17-2011, 1:00 PM
Thanks for the info, an extended mid will be my choice.

Good choice!