Subsonics out of 16" unsuppressed

[SBPA]

I have the freefloat 16" pistol gas and have had since April. Mostly shoot supers out of it as I am still developing loads. Have a word doc that is still being added to but will post it when complete with all the loads, velocity, ect.

Have not had one problem with 123, 125, 130 up to 147 gr supersonic. Does not seem over gassed, no undue marks on buffer, carrier key not hitting back of receiver at all and I am pushing the envelope to see what it can do.

Have shot it with a spare A2 stock lower and carbine lower. No buffer or spring changes, no feeding issues in 4 types of mags and no cycling issues in super or subsonic although I am just starting the sub loads this weekend (180gr). CMMG 175 & Rem 220 subs did cycle fine with and without YHM can attached. CMMG subs did have a bit of unburnt powder.

Have tried a few (10) super through the can and no problem noted but I cannot see myself doing that much because this has the subsonic semi option.

[Foster]

Others have posted (else where) that they have had reliable performance with subsonics out of their 16" carbine length gas systems. I am trying to determine the best coarse of action to get that last little bit needed to achieve the same results. I am not sure if it might be my lower (from a RRA 5.56). I have heard others consider changing to a lighter buffer spring but that does not seem like the direction to go - my take is that opening the diameter of the gas port is the first choice. I was hoping to get some first hand recommendation or a CMMG recommendation.

[USBP379]

My 16" carbine CMMG upper seems to run fine with supers and subs. Not a whole lot of rounds fired but so far so good.

Model 1 Sales makes a 300 Whisper dedicated buffer and spring. If this is a dedicated lower, that might be the way to go.

http://model1sales.com/index.cfm?fuseac ... ory_id=428

[Foster]

Thanks for the info USBP379. I might give that a try.

[USBP379]

Thanks for the info USBP379. I might give that a try.

Let us know how it works.

[Foster]

Well, sounds like it will be a while before my stamp shows up so I places an order for the buffer and spring. Once I have a range report I will post it. Thanks again for the info.

[Bigjakewelch]

I have one (CMMG) with 600+ rounds thru it and it runs subs and suppers fine. Zero issues. It has the carbine gas port with no modifications to it. About to build a SBR in 9" for a supressor. Starting ATF paper work thru a trust this week. Good luck with your feeding issue.

[Foster]

Bigjakewelch, is weapon all cmmg? I my lower is RRA which in its original configuration is a 5.56 which I don't think should matter but wondering if the spring and buffer might be just a bit heavy for subsonics.

[Bigjakewelch]

Bigjakewelch, is weapon all cmmg? I my lower is RRA which in its original configuration is a 5.56 which I don't think should matter but wondering if the spring and buffer might be just a bit heavy for subsonics.

Just the upper is CMMG. I have an Anvil Arms lower that I built with a RRA LPK. The buffer assembly is RRA also. I haven't had a problem with it feeding anything. I went thru all types of ammo configurations wanting to see what worked best out of it. It ate everything that I put thru it. Not sure if it helps you out but good luck. You might want to check and see if your gas key is staked properly. You also might want to check diference with other buffer springs.

[pre86]

I just purchaced one from AIM surplus. Not here yet, but the price was right. Less than $580 including shipping for the carbine version FYI.