SBR Guru's, Your Opinions Please............ [Archive]

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5POINT56

10-26-07, 11:16

This is about a CMMG product and company statement. I am not seeking opinions on CMMG as a company.
I am seeking opinions on a particular SBR upper and their statements about an improvement for SBR reliability.

With that out of the way, here we go.....

CMMG M2SG 10.3 Upper

http://cmmginc.secure-mall.com/shop/images/731.JPG

New 10.3" M2SG MedCon upper. The M2SG upper features a unique secondary micro gas block that diverts gas early into a standard gas tube with a second hole.
Gas diverted forward enters an expansion chamber, created by forward portion of the gas tube, making initial unlock “softer”.
This saves wear and tear on the weapon. Since the gas port is further from the muzzle there is greater residual pressure to ensure increased reliability with ammo ranging from 45 to 77 gr.

Here are my question:

1) LMT has a very good rep all the way around, and their SBR uppers get great reviews...without the "enhancements" noted above.
Is CMMG on to something or is this a fix for a non-existant problem?

2) Is there merit to this CMMG upper design? If so, what? Would it actually improve reliability in your opinion?

Rana

10-26-07, 13:43

I don't have any experience with the CMMG upper, so I can't comment on it.

The LMT 10" is the heat though. With proper ammo the LMT is the the way to fly for a DI SBR. The LMT is a reasonably priced and proven piece of equipment.

I have put 1K's of rounds through 10 " LMT uppers & they RUN!

markm

10-26-07, 14:01

Wow. I've never seen this set up. I'm no fan of anything shorter than 11.5"....

tag for others' opinions.

Paulinski

10-26-07, 14:17

Could this be another gimmic by CMMG (the extra gas port)?:confused:

Somehow LMT, Noveske, Bravo Company upper have only one gas port and they run!

5POINT56

10-26-07, 14:32

Could this be another gimmic by CMMG (the extra gas port)?:confused:

Somehow LMT, Noveske, Bravo Company upper have only one gas port and they run!

Another gimmick?

I asked simply because I'm not well versed on what makes an SBR truly reliable...and CMMG seems to feel they have a winner here.

Does it have merit?

shark31

10-26-07, 15:05

Could this be another gimmic by CMMG (the extra gas port)?:confused:

Somehow LMT, Noveske, Bravo Company upper have only one gas port and they run!

Well this CMMG only has one gasport as well. I imagine it does increase dwell time. However, I feel that there isn't much wrong with an equivelant LMT, BCM, or Colt.

Derek_Connor

10-26-07, 16:22

...................is this a fix for a non-existant problem?

I believe you have answered your own question.

Colt/LMT/Noveske dont seem to need a secondary gas block...

Properly sized and placed gas port should "do the trick"

5POINT56

10-26-07, 17:57

I believe you have answered your own question.

Colt/LMT/Noveske dont seem to need a secondary gas block...

Properly sized and placed gas port should "do the trick"

As good as Colt & LMT are, those two companies, sat on their laurels for years (especially Colt) until the AWB disappeared and the rest of the private sector went NUTS with amazing AR innovation.

Both are playing catch up now. (While their garden variety guns are still outstanding)

So, to me, waiting for Colt & LMT to innovate change isn't the best barometer reading on things....but I hear what you're saying. LMT SBR uppers have a well deserved rep for quality.

S-1

10-27-07, 01:46

I agree with Rana.

If you're looking for a 10.5" upper, the LMT is the way to go.

vinesr6

10-27-07, 16:57

They've had this set-up for a while now, not sure if it helps with reliability. I remember Steve did a similar (somewhat) set-up using an 11.5" bbl.

shark31

10-28-07, 09:49

It's basically an inproved version of the pigtail gastube, draw your own conclusions.

WasatchAR

11-02-07, 08:20

I have had several uppers with problems that could be related to port size. Having a 11 inch barrel can fix some reliability issues, but my 10 inch Noveske has not missed a beat.

C4IGrant

11-02-07, 09:05