Carbine VS. Midlength

[JR TACTICAL]

I have been in recent discussion with a person I respect in the AR world and he has been telling me that midlenght gas systems are the way to go.

He has told me that the midlength system works far more efficient because of the increased length of the gas tube and says that it runs cleaner and has less felt recoil because the has has more time to burn inside the barrel.

I myself only have experience with carbine systems and have never shot a midlength but I recently purchased a DD V5 Upper that is on its way. Do you think I made a good choice???

What is better carbine or midlength

[TehLlama]

You made a good choice. Quality Carbine >> low end midlength.

For 16" barrels midlength does give you less gas (marginally cleaner, less recoil impulse), but a carbine of the same length will probably run a bit longer while dirty.

Barrel material, chamber dimensions, and crown for the barrel, and quality of BCG components are far more relevant to function and accuracy than gas port placement. DD Mk5 - you did good.

[JR TACTICAL]

Why would the carbine run longer when dirty? is it because there is more gas being directed to the gas key in the shorter system?

[BufordTJustice]

Why would the carbine run longer when dirty? is it because there is more gas being directed to the gas key in the shorter system?

Winner winner chicken dinner.

What makes the carbine batter the bolt/bolt-carrier harder and increases the recoil impulse also CAN add to reliability. However, running a bolt carrier group with one of the newer, advanced coatings to reduce friction can take back any 'reliability losses' (whether real or imagined) that may have been lost by the lower gas port pressure. Coatings from Fail Zero, ION Bond, and hard chrome greatly add to any carbine's reliability.

However, I think it would be important to add that 20" rifles, the 'most reliable' iteration of the AR platform, have only about HALF of the gas port pressure of a 16" M4 carbine w/ carbine gas system.

It's a balance between port pressure and dwell time (determined by the length of barrel between the gas port and the muzzle). I'm not sure of the perfect balance, but midlength 14.5" and 16" carbines are darn close to the 20" barreled rifle-gas-system ideal. Sleep well at night with your middy. :)

[ForTehNguyen]

i dunno about cleaner but the middys operating pressures are significantly lower and closer to the rifle gas system, bolt velocity is lower, less recoil, increased sight radius, longer handguard if you need.

All these "features" like M4 feed ramps, extractor 0 rings, higher tension extractors were all made because of the imbalances created when the gas system was cut down.

Armalite Technical Note 48, The Effects of Barrel Design and Heat on Reliability
http://www.armalite.com/images/Tech%20Notes%5CTech%20Note%2048,%20Barrel%20Design,%20Heat,%20and%20Reliability,%20030824%E2%80%A6.pdf

[Boss Hogg]

If you spring/buffer a carbine properly, it will run reliably.

The difference in recoil between it and a midlength isn't nearly as big as you'd expect.

This kit is similar to what Mike Pannone used in his BCM 14.5" carbine "torture test" (2,000 rounds with no lube)
http://www.bhigear.com/bhienhancedm4sopmodboltupgradekit.aspx

[Jay Cunningham]

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