11.5" Barrel Optimum Gas Port Size

[Clint]

Is there any data that even suggests an optimum size?

Every barrel length has an Optimum gas system length and every combination has an Optimum gas port size.

11.5" carbine happens to be one of those OPTIMUM configurations.


Availability in the fall.

Yes on FSB compatibility.

The port sizes aren't set until final testing, but we expect they'll likely be in the high .06x for the standard and low .06x for the suppressor version.

Rest assured they'll NOT be over gassed.

The larger threads are to make the barrel stronger and more accurate.

1/2-28 threads leave very little meat at the critical muzzle crown.

These two M4C threads cover most of the discussion.

https://www.m4carbine.net/showthread...ds-on-5-56-223
https://www.m4carbine.net/showthread...oulder-Barrels

[prepare]

Every barrel length has an Optimum gas system length and every combination has an Optimum gas port size.

11.5" carbine happens to be one of those OPTIMUM configurations.


Availability in the fall.

Yes on FSB compatibility.

The port sizes aren't set until final testing, but we expect they'll likely be in the high .06x for the standard and low .06x for the suppressor version.

Rest assured they'll NOT be over gassed.

The larger threads are to make the barrel stronger and more accurate.

1/2-28 threads leave very little meat at the critical muzzle crown.

These two M4C threads cover most of the discussion.

https://www.m4carbine.net/showthread...ds-on-5-56-223
https://www.m4carbine.net/showthread...oulder-Barrels

Very interesting!
1. What is the criteria for optimum? Reliability to cycle properly, ejection, recoil impulse, mitigate barrel erosion and bolt wear, etc.
2. How is the testing done? Do start with a particular barrel and gas port size and incrementally go smaller while capturing data?

[Clint]

OPTIMUM gas drive starts with matching the gas system length with the barrel length for the cartridge pressure curve to maintain timing ratios in a certain range within the limits of available gas drive.

This is capped off with the final port sizing, with the objective being the widest operational envelope, lowest stress and soft recoil impulse.

More discussion in the mega thread.

https://www.m4carbine.net/showthread...gth-Gas-System

Very interesting!
1. What is the criteria for optimum? Reliability to cycle properly, ejection, recoil impulse, mitigate barrel erosion and bolt wear, etc.
2. How is the testing done? Do start with a particular barrel and gas port size and incrementally go smaller while capturing data?

[JulyAZ]

OPTIMUM gas drive starts with matching the gas system length with the barrel length for the cartridge pressure curve to maintain timing ratios in a certain range within the limits of available gas drive.

This is capped off with the final port sizing, with the objective being the widest operational envelope, lowest stress and soft recoil impulse.

More discussion in the mega thread.

https://www.m4carbine.net/showthread...gth-Gas-System

Sooo...when will we get the 10.3? Lol


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[1168]

Sooo...when will we get the 10.3? Lol


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.....ported for dedicated suppressor use.

[Furbyballer]

Clint, are you going to tune your barrel to a specific 556 load and suppressor? I would be interested to know which 30 cal cans you use in your testing and which performs the best with your barrel. As of now, I can't think of any dedicated 556 cans off the top of my head that use 5/8 x 24 threads.

[MQ105]

The Griffin M4SD series of 5.56 suppressors will attach to the muzzle devices in 5/8 x 24. I'm not sure about other manufacturers.

[markm]

A 30 cal can on an SBR has some appeal. I like the idea of extra baffle diameter for reduced risk of baffle strikes and reduced back pressure.

[Clint]

The Suppressor Gas Drive barrels will be setup for normal function with 7.62 suppressors, which tend to be lower back pressure.

Cycling will speed up a bit if used with higher back pressure 5.56 suppressors, but should still be in a good range.

Clint, are you going to tune your barrel to a specific 556 load and suppressor? I would be interested to know which 30 cal cans you use in your testing and which performs the best with your barrel. As of now, I can't think of any dedicated 556 cans off the top of my head that use 5/8 x 24 threads.

[snackgunner]

Clint would the aac 7.62-sdn-6 suppressor work with this barrel?

Edit : Im reading 5/8x24 i think thats what the 51t 7.62 mount thread is so should be good I think

I like this. I have a sdn6 but dont use it for anything since i dont have any rifle caliber but 5.56 since Im poor. Will go with one of these barrels then