Anyone played with a 12.5" Mid-length Gas System?

[Jmacken37]

I like the recoil impulse on a 14.5" mid-length gas system better than the recoil impulse on a 14.5" carbine-length gas system.

Would I like the recoil impulse on a 12.5" mid-length gas system better than a 12.5" carbine-length setup?

The reason I'm even considering this is this barrel/gas block combo I ran across that looks intriguing...

govnah_12_5_mid.jpg

http://micromoa.com/12-5-midlength-5...rrel-w-govnah/

I have no affiliation with the company.

[Junkie]

I would expect it to be a picky eater. 16" rifle gassed "dissipators" tend to be hard to make run well, and this is a similar concept.

[bp7178]

I would expect it to be a picky eater. 16" rifle gassed "dissipators" tend to be hard to make run well, and this is a similar concept.

All of the dissys I've seen were all carbine gas, but had a FSB installed at the rifle position to make the sight radius as long as possible.

[Steve-0-]

I messed with an early warsport upper that was proprietary as all hell. I ended up cutting down an FN 14.5 middy to 12 and opening the port to .096 and it would cycle PMC on an H Buffer with an A2. That being said, I didnt feel any real advantage in recoil over a properly ported 12.5 carbine length upper. It was minimal.

[Junkie]

All of the dissys I've seen were all carbine gas, but had a FSB installed at the rifle position to make the sight radius as long as possible.

Both styles are available, many people call the style you speak of mock dissipators. I suppose a Colt 605 would have been a better example.

[scooter22]

BCM 12.5" Kino and be done with it

[cgjane]

BCM 12.5" Kino and be done with it

THIS. If all you are after is more rail.

[Jwknutson17]

Depends on the gas port size. And that Govnah?? gas block. Properly ported 12.5 carbine barrels can have very little impulse. I know a few guys on here that run 12.5 mids and have great results with the barrel ported properly (aka large) to run reliably. If running a suppressor I would say go for it. If not, I would rather spend my money on a properly ported barrel and run an A5 system to achieve same results with increased reliability.

I have no experience with Govnah so I don't know what if any part that plays in the system your looking at.

[Rayrevolver]

I was going to build a suppressed only 12.5" Mid using that Micromoa barrel. I decided that was not crazy enough and am trying an 11.5 Mid + SLR sentry. It has a huge port .095" to run unsuppressed I suppose. I bought a cheap Trek TM and will see how it all works out.

The guy from AR Performance sells a 12.5 Mid also and if you search you can find the last thread where they discussed 12.5" Mids.

It wasn't that long ago that people poo-poo'd the 14.5 Mid as being too finicky, but they seem to be accepted today. A proper 12.5" Mid should be ok too (looks like the same dwell time as a 10.5" carbine, no?). I think my 11.5 Mid might be a nightmare...

[Junkie]

The farther from the breech you are, the lower the pressure gets and the higher the velocity gets, so I would expect you'd need more barrel length past the gas port for a longer gas system. Dwell time for the midlength will be shorter than for the carbine with the same distance from gas port to muzzle, and pressure will be lower as well. That's not to say it can't be made to work though.