Recoil difference between GMR-15 vs CMMG RDB 9mm?

[blue72]

Which one has the more pleasant recoil impulse?

[philmadxx]

I own a GMR-15 and have shot CMMG side by side with factory ammo a couple of times.  Doing this, the CMMG has a softer recoil impulse, in my opinion.  I can load ammo that makes the GMR close with some tuning (weights, springs, etc.).

 

Now if your question had been CMMG vs. JP-5............

[blue72]

3 hours ago, philmadxx said:

I own a GMR-15 and have shot CMMG side by side with factory ammo a couple of times.  Doing this, the CMMG has a softer recoil impulse, in my opinion.  I can load ammo that makes the GMR close with some tuning (weights, springs, etc.).

 

Now if your question had been CMMG vs. JP-5............

I’m considering the GMR but I’m concerned the recoil would be too much for me.  I had a ruger PC which I’m not fond of. 

[Ner]

Every gun can be a gmr-15 if you glue half a kilo of weight to it's barrel

[RangerTrace]

Maybe the better question is which one runs more reliably?  

[blue72]

5 hours ago, RangerTrace said:

Maybe the better question is which one runs more reliably?  

I know the GMR is more reliable that’s why I’m considering it

 

However, I don’t want another gun that shoots like my ruger PC, hence why I asked the original question 

 

 

[DarthMarl]

My CMMG has 5K rounds and not a single issue, 124gr handloads

 

[blue72]

1 hour ago, DarthMarl said:

My CMMG has 5K rounds and not a single issue, 124gr handloads

 

Does your bolt have the number 50 on it?

 

apparently cmmg redesigned the bolt, but I haven’t found much info on its reliability from heavy users

[DarthMarl]

I will check the bolt when I get home. I have a 4 inch upper and 16 inch upper, I use the same BCG on both. It also, has no problems with my "out of spec" 9mm

[blue72]

On 2/9/2024 at 9:31 AM, DarthMarl said:

I will check the bolt when I get home. I have a 4 inch upper and 16 inch upper, I use the same BCG on both. It also, has no problems with my "out of spec" 9mm

Ok, thanks!…let me know, I might reconsider the cmmg 

[tt350z]

Check out the MEAN Arms bearing delay upper for another option.

[Joedirt199]

I received an updated bolt from CMMG to try but after reading from others who got the bolt and had the same ejection problems arrise after a few hundred rounds, have decided to abandon the CMMG radial system and just use PSA AR-V receiver set with Maxim Defense Delayed Buffer system. No ejection problems and uses 35 rd Evo mags. I do run it suppressed 100% and it has been way more satisfing then CMMGs RDB offering.

[DarthMarl]

Yes 50 is on underside of the Bolt

[blue72]

13 hours ago, tt350z said:

Check out the MEAN Arms bearing delay upper for another option.

 

13 hours ago, Joedirt199 said:

I received an updated bolt from CMMG to try but after reading from others who got the bolt and had the same ejection problems arrise after a few hundred rounds, have decided to abandon the CMMG radial system and just use PSA AR-V receiver set with Maxim Defense Delayed Buffer system. No ejection problems and uses 35 rd Evo mags. I do run it suppressed 100% and it has been way more satisfing then CMMGs RDB offering.

 

I have considered those. But they are too new and I haven’t seen users with very high round counts yet, to see if it’s a viable option 

looked at Kynshot too, but I’ve seen reports that it has more dot bounce then the JP SCS or CMMG set up.

 

Edited February 11 by blue72

[blue72]

3 hours ago, DarthMarl said:

Yes 50 is on underside of the Bolt

 

thanks for checking!

[Haywizzle]

I'm on the fence with the CMMG setup for my GF's future PCC. I had dreams of chopping a 16" down to 10.5", then pinning a Brekke extended 6" brake to make Maxamundi RDB clone upper with the carbon fiber handguard. While researching, I read this Arfcom thread. I learned about the extractor issue and the updated 9mm bolt with the 50 etched on it. It looks like they changed the angles of the lugs and also the spring to one with over twice as many coils. I've also read some have replaced the extractor with a JP and the spring with a BCM with good results.

 

We aren't sure if we want to spend JP money. Unfortunately she lives in a ban state and can't ordered a JP5. We can piece together a GMR15 or just buy a regular Brekke upper. Decisions, decisions...

[DarthMarl]

You can buy a 8 inch barrel for CMMG

 

[Haywizzle]

On 2/12/2024 at 10:17 AM, DarthMarl said:

You can buy a 8 inch barrel for CMMG

 

Yep. It wouldn't work with the 6" brake/extension and handguard I mentioned to get it over 16".

[philmadxx]

I used to keep up on the latest and greatest recoil systems, buffers, etc.  The main reason I went with the GMR originally is that it is completely reliable, when I pull the trigger, it goes bang - every time. I shoot competitions and one misfire can kill the match, I can screw up and that's on me, but I want the gun to be bulletproof.  The GMR needs no tuning to run all day, every day.  JP has done the tweaking and tuning for you.  

 

I'll admit I haven't kept up with the latest and greatest buffers, bolts, hydraulics, pneumatics, etc.  I'm sure many of those systems are well engineered, but are they engineered as a complete unit?  There are lots of variances and tolerances with parts that these systems need to work with, far too many for any engineer to take into account.  JP does the whole deal and it works.  I am not a JP employee, I just love their stuff.  (Just 0rdered the Ultralight upper for my JP-5).

 

If you like to tweak and are good at it, you can put together a very reliable PCC, so if that's who you are, go for it.  I'm not, I want to shoot, not work on guns.  

 

If you can find a GMR to shoot (if you're ever in MD, look me up), pick up some 150gr Syntecs and see what you think.  You'll be in for a treat.

 

Good luck.