CMMG Guard radially delayed vs. SiG MPX short piston

[Les Snyder]

just wondering if anyone has done a side by side comparison of the two systems .... your perception as to recoil and scope movement... thanks

[cking]

Yes, on first reading I thought MPX short piston would be the way to go, but upon seeing them running and the amount of changes and problems. It is easy to over gas them with too fast of a powder, they were tearing themselves apart. Notice how they kill triggers. Extractors, bolts, gas bleeder. Now the CMMG Guard radial delay taps allot energy and has np piston or gas tapping. So it runs cleaner than MPX. My experience is flatwire/hyd buffer setup Guard , versus stock MPX. To me the guard is softer and smoother

[jcmusika]

I too am interested in people's observations between the 2 models

[Aircooled6racer]

Hello: I have now shot both the Guard and the Sig MPX. The Sig shoots softer than the Guard. The guard was all stock using my AR9mm 124gr reloads which are 131-134 in my AR9 and the owner says his load was a little hotter than mine. My Sig load is in the 138-141 range using 115's. The Guard does shoot pretty flat and I think it could use a little tuning in the buffer setup as well as a lighter handguard. I did notice a double recoil impulse on the Guard which could be the AR15 carbine buffer or the bolt coming unlocked. It will be interseting to see how the Guard holds up. I think both will work very well for competition or plinking. An AR9 blowback works well also with the right setup. Pick one and shoot it alot. Thanks, Eric

[BartCarter]

On 4/15/2018 at 8:47 PM, cking said:

Yes, on first reading I thought MPX short piston would be the way to go, but upon seeing them running and the amount of changes and problems. It is easy to over gas them with too fast of a powder, they were tearing themselves apart. Notice how they kill triggers. Extractors, bolts, gas bleeder. Now the CMMG Guard radial delay taps allot energy and has np piston or gas tapping. So it runs cleaner than MPX. My experience is flatwire/hyd buffer setup Guard , versus stock MPX. To me the guard is softer and smoother

 

Upon reading your previous posts, I changed to a hydraulic buffer.  And thanks for the response about the AR15 length buffer.  I have the flatwire spring, but haven't put it in yet.  Although the difference is not night and day, I do like it better.

 

On the buffer, there is one available for the "less powerful" 300 Blackout. 

 

KYN-RB5000L

KynShot Hydraulic Recoil Buffer AR-15 Carbine (3.25") - LIGHT

 

I chose this one, but I don't know what the effect is for a 9mm over the standard AR15.  Anyone know?

[BartCarter]

Shot the TPC Carbine Class this weekend.  3 days, over 1600 rounds for me as you can really shoot as much as you want.  I did a quick clean and lube every night (around 500 rounds a day).  There were only 8 students with 3 instructors.  The instructors were not only knowledgeable being able to actually instruct, but were all world class shooters.  Class was exceptional and I was finally able to put into action many concepts that I knew, but couldn't perform because of shooting the way most of us are taught.  Now for those 20,000 repetitions to ingrain the new. 

 

My Guard ran without a hitch.  Fiocchi 115s.  I am probably at about 4-5,000 rounds by now.  Everything worked as designed.  When I say "my" Guard, it was built with the Guard lower, BCG and 8.5" barrel.  In retrospect, I would use their upper too instead of milling out the ejection port in an upper that I already had.  I have never had any problem with the Guard, it has always functioned 100%.  I see many malfunctions from other PCCs in matches, but the Guard just runs.  Of course the Colts I have built run too.

 

The MPX, not as good, failing to feed occasionally.  They were adjusting on it quite a bit.  It was fairly new, so maybe needed some fiddling to get everything right. 

 

We swapped in order to get a comparison.  The MPX was factory stock.  I liked the way the MPX shot, seemed maybe a little softer, but he was not running off-the-shelf ammo.  Fairly flat shooting.  The differences to me were not significant.  Like Eric says, "Pick one and shoot it a lot."   

[cking]

One update on my guard, I turned the 8 and a half inch barrel down 5\8" 0D  running a comp on the front. Using a 7 inch aluminum hanguard with the aluminum barrel nut also.

[Aircooled6racer]

Hello: At the JP PCC championship match this past weekend the first and 3rd place shooters where both shooting a Sig MPX. Todd shoots a lot of rifles but Chris is mostly an open shooter so that says something for the SIg. I am not saying the Guard could not do the same thing in the right hands. Reloaded ammo can be a problem with any PCC and I have used factory ammo that has not run 100% in my PCC's also. Chrono some factory ammo and you will see how it is. Thanks, Eric

[BartCarter]

40 minutes ago, Aircooled6racer said:

Hello: At the JP PCC championship match this past weekend the first and 3rd place shooters where both shooting a Sig MPX. Todd shoots a lot of rifles but Chris is mostly an open shooter so that says something for the SIg. I am not saying the Guard could not do the same thing in the right hands. Reloaded ammo can be a problem with any PCC and I have used factory ammo that has not run 100% in my PCC's also. Chrono some factory ammo and you will see how it is. Thanks, Eric

 

Completely agree with everything you said.  Hope no one was inferring anything negative against the Sig in my post.  I was just giving my info on my Guard and the ammo that was used.  (I have never used any other ammo.)

 

On the MPX, Kurt was deadly with it, shooting much better than I did.  (Of course Kurt is a much better shooter than I am. )  My remarks on some of the failures to feed were just to show I felt the Guard was a dependable choice compared to others as any PCC can experience [fixable] problems.

 

Again, your advice to pick one and shoot it a lot was the home run.

[cking]

I know 2 mpx owners both have had to send their guns back to SIG both are pretty sensitive to ammo. So far my CMMG has eaten everything, reloads, hollow points, however no testing with a can.

[Tan40]

I also shot the JP PCC match and I was an RO at the match. I witnessed a lot of malfunctions out of a lot of different styles of PCCs. But he MPX was the worst offender on our stage. 

I shoot an MPX, and it is by far the best shooting (softest) out of any AR style 9mm I have shot. It takes a lot of love and experience to keep the MPX reliable. But it can be done. I shoot more 3gun than anything and I don’t change my 125gr load just for the MPX. I just clean and manage springs and piston/plug rings a lot!!!!

 

The best advise is to get one platform and learn it well.