Help clarify carbine vs. mid length vs. ext. mid and rifle length gas systems

[Falstaff]

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]

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]

Looks answered to me.

[451040]

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"


VIS-2 - standard midlength 9"


VIS -2A - extended midlength 10"

the 2A covers the gas block of a mid length system


VIS-3 - standard rifle 12"

the 3 extends 2" past the gas block of a mid length system

[Falstaff]

Thanks for the info, an extended mid will be my choice.

[cmace22]

Thanks for the info, an extended mid will be my choice.

Good choice!