16" Barrel and rifle lenght gas port location

[Marc]

I did read different post about barrel and gas port lenghts but I didn't found a lot of explanations about that configuration.
Is it because it's the baddest one in terms of realiabilty?
I would like to have some more advice about that.
Can it be good only with the use of a silencer and in relatively hot countries?
Many thanks.
Marc.
Belgium.
Sorry for my English. Not enough practice any more!

[gotm4]

I did read different post about barrel and gas port lenghts but I didn't found a lot of explanations about that configuration.
Is it because it's the baddest one in terms of realiabilty?
I would like to have some more advice about that.
Can it be good only with the use of a silencer and in relatively hot countries?
Many thanks.
Marc.
Belgium.
Sorry for my English. Not enough practice any more!

Welcome Marc.

A CAR length gas system is the hardest on parts and cycles the most violently. Its the reason why H, H2 and H3 buffers were developed along with stronger extractor springs and extractor enhancers like the Crane 0-ring and the MGI D-fender. (This is why I also recommend using M16 carriers when possible, to at least use the weight carrier the gun was designed around).

In the U.S. one must use a 16" barrel by law (unless they have a tax stamp for a licensed machinegun or short barreled rifle). So a mid-length (2 inches longer & roughly 9K psi less pressure) gas system is a better option since the barrel is 16" anyway. Mid-lengths run lower gas pressures and don't suffer the problems that 16" CAR gas lengths do. Which is hard extraction, shorter bolt life etc. Mid-lengths also give you 2" longer rails/handguards and get your iron sights further apart which is better for longer shots if using iron sights.

Yes gas pressures and bullet velocities increases as temperature increases. With a CAR gas system this could get really ugly in some hot climates if shooting a lot and shooting a lot rapidly. A mid-length or even a rifle length would do much better in that type of climate.

[Marc]

Hello gotm4. Thanks for your welcome and comments.

Can't you give me more comments about that configuration?

The goal is to know if that can be as realiable as a rifle using a carbine stock, spring and buffer with a chopped 20" barrel.

Thanks again.
Marc.

[KevinB]

Short answer "maybe"

You will likley have to have the port expanded to make a "disapator" style gun run.
IMHO there are not a lot of plusses to that design - other than a longer sight radius - and in the days of optics...

I've never known anyone with a setup like that that runs well.

[DRich]

I used to use this setup as my primary carbine. It's a DPMS 16" barrel with the rifle length gas system. Not sure if they still produce this variation or not. It was delivered as an HBAR, but I had it turned down under the hanguards. Very light and balanced well.

http://texbiker.com/pics/dpms1.jpg

It was ammo sensitive, but ran 100% with M193 or M855 in winter/summer. Went through the 3-day carbine class at Thunder ranch without an issue. However, it would short stroke on lighter loads. I wouldn't pick this configuration if absolute reliability was my main concern. The midlength and carbine gas systems are much more forgiving with 16" barrels, IMO.

[Marc]

Hello Kevin, thanks for your reply.

Hi DRich, thank you for your explanations.
I never use under power ammo only 5,56mm. NATO so I should make it work.