13.7" Midlength?

[Ubaderb]

I just ordered Triarc Sytems 13.7" Track Barrel which is a mid-Length. Hurry up SHOT show and end so I can get my stuff! ...Will report back once I get everything put together. But good to know there's another option on the market.

https://www.triarcsystems.com/rifles...ck-barrel.html

Meant to include this in my previous reply, but I went ahead and emailed them to see what they said about the barrel. I’ve heard good things about Triarc.

[Clint]

Wouldn't a 13.7" mid have roughly the same dwell time as a 11.5" carbine, what with the gas port being 2" further out?

Granted, the bullet is going faster there, but still...

Yes, the distance is longer but the velocity is higher, so power time ends up nearly identical.

The gas system is longer, so pressure is lower, of course.

The key to a good gas system configuration is not just matching the power time of some other configuration, but balancing it with the gas system length to create optimal timing while keeping the available gas drive on a workable range.

[Ubaderb]

Yes, the distance is longer but the velocity is higher, so power time ends up nearly identical.

The gas system is longer, so pressure is lower, of course.

The key to a good gas system configuration is not just matching the power time of some other configuration, but balancing it with the gas system length to create optimal timing while keeping the available gas drive on a workable range.

So considering all of that, what would be the optimal gas port size be for my setup? I assume that's what you mean by this correct?

[Clint]

The key to a good gas system configuration is not just matching the power time of some other configuration, but balancing it with the gas system length to create optimal timing while keeping the available gas drive in a workable range.

So considering all of that, what would be the optimal gas port size be for my setup? I assume that's what you mean by this correct?

All that was in reference to selecting a configuration (combination) of gas system length and barrel length before the gas port is "sized".

The gas port size takes the "available gas drive" and scales it down to the actual gas drive.


As for the size,

The 13.7 should actually be great for mixed suppressed use, especially if cut down from a 14.5 or 16" mid with no port modifications.

[Grip]

what would be the best 50/50 mixed use port size for a 13.7" mid gas barrel?

[Boba Fett v2]

This is a Noveske 13.7 middy barrel build. Currently running an A5H2. Nice and smooth. No issues. Will be testing it with a Saker 556 can later this week. Muzzle device is a Dead Air three prong flash hider, which bring the overall length to just over 16" (pictured with a Dead Air pyro mounted of course)

[AAMP84]

This is a Noveske 13.7 middy barrel build. Currently running an A5H2. Nice and smooth. No issues. Will be testing it with a Saker 556 can later this week. Muzzle device is a Dead Air three prong flash hider, which bring the overall length to just over 16" (pictured with a Dead Air pyro mounted of course)

Nice! I was wondering if the Pyro would work with the MK8.

[Grip]

This is a Noveske 13.7 middy barrel build. Currently running an A5H2. Nice and smooth. No issues. Will be testing it with a Saker 556 can later this week. Muzzle device is a Dead Air three prong flash hider, which bring the overall length to just over 16" (pictured with a Dead Air pyro mounted of course)

my gun ran flawlessly until I added a suppressor. Curious to see what results you get with the A5 setup. also what ammo will you be shooting?

[Boba Fett v2]

my gun ran flawlessly until I added a suppressor. Curious to see what results you get with the A5 setup. also what ammo will you be shooting?

Running Federal XM193 for this test run.

This video demonstrates firing unsuppressed, with the Pyro attached and finally with the Saker 556. The last string did not appear to be a malfunction of the weapon, but a failure of the magazine to lock the bolt back after the last round. ETA2: the rounds are ejecting just forward of the 3 o'clock position when running the can, a little bit over-gassed, so that could've attributed to the bolt not lacking back right there, but again it seemed to run fine in the newer USGI mags. ETA3: Also, as my good friend E-man930 pointed out, the ejection pattern here seems a little erratic, not severe, but perhaps not as optimal as it could be. The spring within the buffer itself (originally an H4, but was converted down to an H2) might be contributing to it. Will continue to fine tune as applicable.



Used five mags during the test run. Of the five, two magazines failed to lock back after rounds complete, which was an older gen PMAG and a 3rd gen USGI mag. The two mags that worked flawlessly were the latest gen USGI mags (blue followers). One mag was causing a type III malfunction, which was one of the older gen USGI mags. Once that mag was ditched, the rifle ran flawlessly suppressed for the remainder of the session. 120 rounds total were expended. Didn't have a lot of time to run more, but I hope to get back out within a week or so to continue experimenting with different ammo and magazines.

ETA: the fireball from the pyro is insane

[msnyder0609]

I received the Triarc 13.7" Track barrel today. Won't be able to shoot it for a few days, but I wanted to post a bit of info for you guys now that I have it in hand.

It measures exactly 13.75. Trying to be as accurate as possible with calipers (no pin gauges on hand) the port appears to be roughly .077.

In regards to the barrel length. For those considering pinning a Dead Air flash hider, it looks like a spacer would be needed to get to 16.1. 13.75 + 2.70 = 16.45, subtract .60 (right?) for the threads and that puts you at 15.85.

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