BCM 14.5" mid-length barrel gas block - adjustable or not

[Benito]

My research tells me that the BCM 14.5 middies have a gas port diameter of 0.078" (if someone could verify this, that would be great).
The question I have is whether this particular barrel/gas system/gas port combo should be paired with an adjustable gas block if running suppressed, if one wants a relatively tame, non-severely over gassed, beat itself to death setup to run suppressed while still being able to cycle a variety of brass cases 5.56 and .223 factory ammo with no can.
The dwell time and gas port size seem to be a bit lower that most other combos (except for can-dedicated barrels like Faxon's 11.5/12.5 mid lengths, which will not cycle unsuppressed).
Curious what people's experiences/insights are on this.

[Rascally]

Since it's a BCM, I'm pretty sure it would run. Would it be optimal, probably not. While an adjustable gas block would make it easier to get close to optimal in both conditions (suppressed and unsuppressed), it is one more complication and thing to go wrong, plus you'd need to have the allen wrench to adjust it. I guess you could just carry an extra buffer and swap those out when switching... Does Noveskie still make the Switchblock?

[Jwknutson17]

My research tells me that the BCM 14.5 middies have a gas port diameter of 0.078" (if someone could verify this, that would be great).
The question I have is whether this particular barrel/gas system/gas port combo should be paired with an adjustable gas block if running suppressed, if one wants a relatively tame, non-severely over gassed, beat itself to death setup to run suppressed while still being able to cycle a variety of brass cases 5.56 and .223 factory ammo with no can.
The dwell time and gas port size seem to be a bit lower that most other combos (except for can-dedicated barrels like Faxon's 11.5/12.5 mid lengths, which will not cycle unsuppressed).
Curious what people's experiences/insights are on this.

I have measured the 3 that I own BCM mid 14.5 gas ports all in the .076-8 range. I have run all 3 of these guns suppressed. You will want an Adj gas block from my experiences. No point and spending all this money trying to bandaid it when you can go to the source. Get a SLR and run a H2 or A5H2 and tune it down. Unless you are going to buy a specific barrel with a specific port, and chop it down, the Adj gas block is the way to go.

[scooter22]

I have measured the 3 that I own BCM mid 14.5 gas ports all in the .076-8 range. I have run all 3 of these guns suppressed. You will want an Adj gas block from my experiences. No point and spending all this money trying to bandaid it when you can go to the source. Get a SLR and run a H2 or A5H2 and tune it down. Unless you are going to buy a specific barrel with a specific port, and chop it down, the Adj gas block is the way to go.

Yep. Virtually every barrel is over-gassed these days. Adjustable block is the way to go if you're going to suppress.

[markm]

BCM's 14.5 middies are NOT over gassed. In fact, I buffer down my 14.5 middies to an H2 carbine system to allow for .223 pressure ammo. I run a dedicated suppressed 14.5 middy with no adjustable gas system. Not needed in my opinion.

[Benito]

Good info. Thanks gentlemen

[Ryno12]

I agree with Mark. I saw no need for an adjustable GB when I was running my 14.5" BCM suppressed. I used an H2 buffer whether I was shooting canned or not.

[Benito]

I agree with Mark. I saw no need for an adjustable GB when I was running my 14.5" BCM suppressed. I used an H2 buffer whether I was shooting canned or not.

Ryno and markm, I am curious about how/why you determined that. Did you have a baseline for comparison like an very added suppressed carbine gas system gun, or one with a large gas port, observe the ejection pattern, measure the bolt carrier velocity, etc.
Where does your 14.5 middie eject the cases when suppressed (1, 2, 3, 4 o'clock, etc)

[markm]

Ryno and markm, I am curious about how/why you determined that. Did you have a baseline for comparison like an very added suppressed carbine gas system gun, or one with a large gas port, observe the ejection pattern, measure the bolt carrier velocity, etc.

Yes to all of the above. I've got too many examples to list... but off the top of my head, I've...

1. Compared BCM's 14.5 middy against a 14.5 middy with an .080" port. The .080" port isn't too much gas, and probably ideal if you shoot a lot of mild ammo.

2. I've compared the BCM middy against an over gassed carbine in full auto fire. BCM's was miles smoother and more controllable.

3. I ran a BCM middy full auto without a suppressor for 8-10 rounds, mounted the can and mag changed for another 8-10 rounds for a video that showed the cyclic rate impact of the suppressor.

I've done a bunch of other ammo, and recoil impulse tests that, although not perfectly scientific, have given me a pretty damned good idea of what works in the 14.5 middy.

[jpmuscle]

Side note. Is it possible to weld up and re-drill a gas port to the proper (i.e. smaller) diameter? Assuming its a relatively low round barrel with zero port erosion? Just a ponder as I've never read of it being done (yes, I realize that's probably a clue).