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View Full Version : 18" barrel, midlength or riflelength gas system?


tomd1584
10-04-2009, 9:17 PM
I read a thread over on M4carbine a few weeks ago and now I cant seem to find it.

I'm looking to buy another upper, an 18" and for some reason I remember reading that the midlength gas system is a better fit than the rifle length. Is this correct?

Ideally I'd like to swap onto my only lower, will this run reliably with a H1 buffer?

Thank you,

-Tom

rabagley
10-04-2009, 9:21 PM
Why use an H1 buffer? 18" rifle should work just fine, and in general, use the longest gas system that will reliably cycle the action.

tomd1584
10-04-2009, 9:25 PM
Right now I have a 14.7" upper and use a H1 buffer.

If the 18" will cycle properly with that buffer, it will save me money from buying another one when I switch uppers.

hopefully that clarifies.

Edit: what buffer do you guys usually use with an 18" barrel?

Crusader
10-04-2009, 10:02 PM
I would go with a rifle length system on an 18" barrel... cleaner, less recoil, and in my opinion more comfortable/flexible options.

pacrimguru
10-04-2009, 10:04 PM
i have an 18" with midlength and tried both stardard and H1 buffers with it. both worked perfectly, but i liked the H1 better.

tomd1584
10-04-2009, 10:52 PM
i have an 18" with midlength and tried both stardard and H1 buffers with it. both worked perfectly, but i liked the H1 better.

thanks for the help, I'm hoping to place an order sometime this week.

-Tom

evollep3
10-05-2009, 12:02 AM
i have a 18" WOA midlength and the H1 cycles great

slappomatt
10-05-2009, 6:57 AM
rifle for sure. I plan on doing that some day as well.

pacrimguru
10-05-2009, 9:06 AM
i have an 18" with midlength and tried both stardard and H1 buffers with it. both worked perfectly, but i liked the H1 better.

doh! correction, i don't know what i was thinking, i have a RIFLE length 18" barrel. not a middy. sorry about that! the rifle length system runs smooooth with an H1.

eaglemike
10-05-2009, 9:08 AM
I built an 18" rifle length, using a CMMG barrel. Runs like a timex.

all the best,
Mike

BHPFan
10-05-2009, 9:18 AM
Either will suit fine, but I prefer rifle length.

tomd1584
10-05-2009, 9:26 AM
doh! correction, i don't know what i was thinking, i have a RIFLE length 18" barrel. not a middy. sorry about that! the rifle length system runs smooooth with an H1.

Thank you for your clarification!

I built an 18" rifle length, using a CMMG barrel. Runs like a timex.

all the best,
Mike

THank you. Thats exactly the upper I'm looking at.

Either will suit fine, but I prefer rifle length.

Again, thank you for your input.

ar15barrels
10-05-2009, 9:27 AM
For warm weather (above 40 degrees f), go with a rifle length gas system.
If you will be using it in sub-freezing weather with weak ammo, go mid-length.

The reason everyone with mid-length 18" barrels are running H1 buffers is that the 18" mid-length barrel is an over-gassed design just like a 16" carbine.
18" barrels can be optimized with an intermediate-length gas system that falls between mid-length and rifle length.