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Everything is a balancing act.
For best extraction, you want to have the chamber pressure as low as possible. This implies a long gas port location.
In order to cycle the action, you need a particular amount of gas impulse. This is pressure x time. Time that the piston is under pressure is related to the distance from the gas port to the muzzle. More time implies a short gas port location or a long barrel.
Pressure in the gas system is related to the available chamber pressure and the gas port size.
The rifle length system extracts well under low chamber pressures, but requires a 20" barrel.
The carbine system suffers from early extraction and high gas port pressures but works well with barrels as short as 10"-12".
The midlength system splits the difference and works well with 14-16" barrels.
Black River Tactical
BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
BRT EZTUNE Preset Gas Tubes - CAR and MID
BRT Covert Comps 7.62, 5.56, 6X, 9mm
BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
BRT MicroPin Gas Blocks - .750" & .625"
BRT MicroTUNE Adjustable Gas Blocks
BRT CustomTUNE Gas Ports
Is a carbine system going to be more reliable with cheap low powered .223 that might short stroke a middy? Serious question.
C co 1/30th Infantry Regiment
3rd Brigade 3rd Infantry Division
2002-2006
OIF 1 and 3
IraqGunz:
No dude is going to get shot in the chest at 300 yards and look down and say "What is that, a 3 MOA group?"
these carbine vs mid threads are always an example of how poor the ar15 system is mechanically.
There's only 3 things we can manipulate on a 223/5.56mm ar15 for best performance.
1. gas port location
2. extractor tension.
3. 5.56mm NATO chamber.
Some things we can't change in the 223/5.56mm ar15 system is....
1. extractor circumference
2. weak rim on 223/5.56mm casing
3. poor taper on 223/5.56mm casing
4. lack of primary extraction on ar15 system
Yes the port size and buffer weight can definitely be changed for a desired result.What about also "manipulating" :
1. gas port size
2. buffer weight
The reason I didn't mention gas port size is because of the possibility of erosion indifference. Meaning, although an M4 barrel can be manufactured with a smaller gas port diameter, it will only delay the erosion process and will eventually end up as worn out as a regular M4 barrel gas port but with more rounds through.
I have no way of proving this and that's why I left it out. But the idea is that the size of the port will not decrease the violent abrasion/pressure of hot gas closer to the chamber as opposed to a gas port drilled closer to the muzzle of the same barrel length.
I left out buffer weight because I figured increasing the gas system length would be a better permanent solution. This would be purely opinion at this point.
I've only owned middies until recently. Honestly, when I picked up my first one, I simply preferred the look of the middies on a 16" barrel.
Now that I have a carbine length, I prefer the increased real estate and longer site radius of the mids.
If I had started with carbines, I don't think I'd spend the cash to replace them with mid-lengths unless someone could show me a controlled study showing significant reliability improvements, but I don't expect to buy carbine length gas unless I'm getting a shorty.
I would love hard evidence that proves a tiny bit of more space on the camming track is going to significantly increase extraction reliability for high pressure 5.56mm nato ammo, as well as 223 steel cased ammo in various 14.5/16" carbine/mid-length systems, assuming everything else is untouched.4. Dwell time (for example LMT enhanced carrier)
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