Over-gassed 11.5.. cut to 10.5 help at all??

[MegademiC]

https://en.m.wikipedia.org/wiki/Choked_flow

https://en.m.wikipedia.org/wiki/Orifice_plate

From choked flow:

"The choked flow of gases is useful in many engineering applications because the mass flow rate is independent of the downstream pressure, and depends only on the temperature and pressure and hence the density of the gas on the upstream side of the restriction. Under choked conditions, valves and calibrated orifice plates can be used to produce a desired mass flow rate."

Thanks, I was specifically referring to the behavior of supersonic gasses, and the theory behind what causes them to slow down... or is that explained by the above and I'm just not getting it?

[Junkie]

The difference in "dwell time" between a 14.5" and a 16" (or even a 20") barrel is a fraction of a micro second.

If "dwell time" made a difference, suppressors would not affect carrier speeds. Suppressors increase carrier speed because they increase the amount of time it takes pressures in the bore to drop after the bullet exits. Gas operated rifle operate on residual pressure, the pressure in the bore after the bullet exits

It's entirely possible for a variable to make a difference, but not be the only thing that makes a difference.

[Clint]

Thanks, I was specifically referring to the behavior of supersonic gasses, and the theory behind what causes them to slow down... or is that explained by the above and I'm just not getting it?

Supersonic and Subsonic flows react completely opposite when encountering nozzles, diffusers and orifices.

https://en.wikipedia.org/wiki/Compre..._Laval_nozzles

[markm]

Why rocksett?

Just adds a little "glue" to hold it in place. The insert can only go so far IN or OUT anyway. I'm just anal about things.

[BufordTJustice]

No need to overthink things.

In our experience, the insertable ports flow very similarly to the equal size barrel port.

You may get some variations in gas drive with different barrels, but most of those differences can be attributed to variations in bore diameter and gas block/gas tube leaks.

The size of the existing barrel port does not change the required insert size.

Given the relevent application parameters, we can recommend a size that works nicely on the first try better than 90% of the time.

Yeah, due to the early unlocking relative to longer barrels and gas system lengths, I suspect chamber dimensions may play a larger role in SBRs than in their​ bigger brothers.

Regarding Mark's observations on SBRs, I've found that as well that each barrel is its own animal to a degree when dealing with different manufacturers, even quality ones.

I think this is where it is critical to have a properly bored 556 NATO chamber for an SBR.

[markm]

Regarding Mark's observations on SBRs, I've found that as well that each barrel is its own animal to a degree when dealing with different manufacturers, even quality ones.

I think this is where it is critical to have a properly bored 556 NATO chamber for an SBR.

Yep. None of the guns we've messed with are problematic. We can just observe recoil impulse variances when jumping from gun to gun.

[MegademiC]

Supersonic and Subsonic flows react completely opposite when encountering nozzles, diffusers and orifices.

https://en.wikipedia.org/wiki/Compre..._Laval_nozzles

Good stuff thanks!

[JG007]

Surprised I haven't seen gunsmiths offering to 'comp' a barrel by drilling holes at the end to reduce gas. Easier than chopping and you don't have to re crown and thread

[jpmuscle]

WAY better heat tolerance than Loctite, if you were wondering why a threadlocker.

Right. But there is no way for the port to come out?

[jpmuscle]

Additional question. Is it possible for a port to be welded and redrilled with no detrimental effects?

Full disclosure I dont know sciency engineering stuff lol