You can get an entire 16" upper from PSA for under 3 bills.  I went that way so I could get the BCG for my 22LR build upper copy of my 9mm build.  But, that 16" PSA upper is a shooter.

Heavy?.....time to hit the gym or have your husband carry it for you

Seriously though I agree they are on the heavy side for what they are.

Well the notion of having to mod anything to use the rdb is a no go. I’d still rather have a functioning hanh block/blowback just in case. I won’t ever look back to blowback 9mm. As always your insight and testing/development is a great value to all the forums we frequent. Will have to shoot together sometime when i pick up on MG matches and able to travel.

Oh i’d probably only do it once or twice. i can only imagine how brutal it would be. Just trying to show the modularity of not having to do absolutely anything to swap between uppers. Once i get all them done and working. Gonna make carrying case with minimum of 4 uppers and two mags each with my one RR. Nice to have variety when out plinking with minimal other guns.

I wish i had bought an RDIAS back when they were cheaper than converted RR’s. But they are $35k now! Wowzers. It would be nice to just toss in a different gun. But i’m trying to accomplish the same with an RR. An RDIAS is capable of everything i’m trying to accomplish anyways. One lower w/multiple uppers. My path is more for those who have only a RR

My ultimate goal is one lower, no switching of buffers or anything. Just swap an go. But at the sacrifice of the sweet spot (Rof) for any one particular caliber. So far i’m happy with my .22 (obviously no tinkering) my 9mm supers and subs are great, 5.56 only shoot supers anyways, 300blk super/subs work flawlessly. Next will be a short 7.62x39 (just to take place of 5.56 due to ammo costs), but only 30rd mags are available for AK in ar magwell right? But i also like to do mag dumps with my beta and Saw Drums. I have yet to test my XM-1 Lakeside belt and the FM-9 belt.

5.6# on bathroom scale. Foregrip and aluminum hood shroud on mrds is 1/4#. Pretty light to me utilizing RDB system.

https://flic.kr/p/2hVmDh1

Maybe?

Can always turn down or flute the barrel, swap to a thinner/lighter handguard, choose a smaller/lighter red dot, same goes for light, try a lighter minimalist stock, and so on...

My Colt mag AR9 is heavy.  Not crazy heavy, but heavy.  It has a fairly heavy flashlight on it.  The barrel is a 5.5".  I put a Sparc AR optic on it and shot it.  I prefer the TRS25.  I use a very heavy buffer and a springCo red spring in it.  The recoil is more of a chug and is very easy to control.  I let people at the range I go to shoot it and they are surprised by the weight as well as the chug of the recoil, but  no one has ever complained about the recoil.  With the can it is even nicer.



My Glock mag AR9 is actually slightly lighter.  More than likely due to the light and polymer magazine.  It's a 8.5" with same very heavy 9mm buffer and SpringCo red spring.  People I let shoot it love it.  I let a guy shoot it, then his wife, and then his 13yr old son.  The kid reloaded the mag twice (their own ammo, 33rd mag so 66rds).  No complaints of recoil.



I have been extremely lucky in the fact that on both all I have had to do was tweek the ejector a little and they have ran flawlessly.  I'd love a MP% or even the CMMG delayed setup, but these 2 just work.

16” barrel, full length hand guard and currently CTR stock.  Nope, not heavy at all.

Recoil?  Maybe?  It’s not a .22 and not a 300WM.  Recoil seems appropriate for size knowing what it is.  It doesn’t pretend to be anything other than what it is.

At 25yds a quick group is all in the T box.  What more do you want/need from a HD PCC?

I don't notice a difference until I stick a loaded 32 round magazine in it.

This is the best answer imo. Mpx.

I honestly think the MCX is also an improvement on the AR platform

I have a post sample full auto MPX and hate it...terrible suppressor host.  Gassy and loud.  No good way to lock the bolt back from the right side either.  Basically not tuneable either.

ILWT has come out with agbs and smaller gas port sizes

G and ilwt has came out with differnt weight recoil springs

Simi isnt gassy enough for me to pick up either one

I already have the ILWT 4 position regulator....it works but I find that it either goes from not cycling to working then overgassed and more overgassed....the setting where it is working is still too gassy with a suppressor.

I think the MPX has a smaller operating window than other 9mm SMG's.

Below is a picture of mine.  That is unsuppressed and using the ILWT 3 lug barrel.  Suppressed, the cyclic rate is even higher.  Changing recoil springs will not drop the cyclic rate significantly enough to make a difference.

Since the CMMG RDB is basically an AR, there are a plethora of various buffers, springs etc to choose from.  I can reliably make it shoot in the 500's to the 1000's at will.  Get any ambi lower I want, etc...with suppression on par with the MP5.

The MPX's piston is just too loud when suppressed....now I've heard that going with an integral suppressor on the MPX works well but I'm done spending money on mine.

Problems I wish I had...ha

Edit: actually forgot about the time my hiperfire disco broke and mag dumped. Cycled so fast It sounded like on load noise. So I can understand that it prob does cycle way to fast in FA. However in simi I think it's one of the smoothest shooters I've ever used. Wolfman didnt seem very gassy. Do you feel the same in simi?

Jesus man. Hyperbole much?

My shooting buddy has a Guard. 8” barrel (pistol with brace), Glock mag. I have an AR9 5.5” barrel (SBR) Glock mag, with BAD PDW stock system and binary trigger. Shooting them side by side (semi) any difference is negligible, at least to us. Now mine does get gassy when I go binary, but it does have a Omega 9k on it. Whereas his doesn’t have a binary and also wears a Hyrbid (46 bore) so there isn’t an apples to apples.

Maybe full auto the CMMG shines, but plinking steel at the range in semi... flip a coin... well once I got his bolt catch to actually start locking back after some tweaking.

Not too much.

Some weights on similarly equipped guns:
4.5" AR-22 5lbs 14oz
M&P 15-22 rifle 5lbs 14oz (polymer upper/lower)
7" 5.56 6.5lbs (heavy barrel)
10" AR-9 7.5lbs
10.5" 5.56 8.5lbs (heavy barrel)
16" AR-15 9lbs (medium weight barrel)

They do balance a bit differently, with a high mass bolt and extra heavy buffer. I find that a supportive brace or a stock with a wider, rubber recoil pad makes all the difference. Recoil is a little more abrupt than the gas operated guns, but is in no way intrusive.

LOL...hey just calling it as I see it. I dunno how consistent you shoot your binary, but behind a FA gun, the difference is significant. The weight savings and versatility of tuning ROF is a big factor for me. I plan on getting into MG competition shoots. Semi auto, you can kind of tell and yes unless the guns are apples to apples most would not be able to tell. YMMV. If you get a chance try a RDB in FA or if you're ever in my neck of the woods I'll let you shoot mine. (South Central Kansas).

Yes, even in semi, I don't like it.  Like many straight blowback AR9's you are really supposed to use specific trigger groups in the MPX...hence Geissele making a trigger specifically for the MPX.  I was running my MPX with a milspec full auto fire control and briefly with a Geissele SSF.  With the milspec full auto fire control, even in semi auto I was getting some horrendous trigger slap.

Having to use special triggers is not an issue with the CMMG RDB.

Even in semi, the piston design is just too loud with a muzzle can with an MPX compared to even a straight blow back AR9 and way behind the CMMG RDB or MP5.

Below is copy and paste of what I posted here: https://www.ar15.com/forums/armory/Straight-blowback-is-100-unacceptable-imo/48-500494/&page=6#i5216783
I'll repeat it here is since it is relevant to this discussion.

I don't know what buffer setup your buddy has in his 8" Guard but as I've posted many times, I wasn't that impressed with the CMMG Guard's recoil impulse with the CMMG recommended buffer/spring setup but felt that since it is basicallly an AR that it had great potential in tuning which is why I went through all the tweaking documented here: http://c3junkie.com/?page_id=538

I need to do another high speed video showing a stock CMMG RDB 9mm bolt and only using my preferred buffer setup: A5 tube / Kynshot RB5007 / 556 Tubb flat spring.
That is noticeably smoother than the stock CMMG setup which widens the gap between a straight blowback AR9 and the CMMG RDB.
I think if you shoot that side by side a straight blowback AR9 it is very noticeable...again, this setup requires no custom parts or modification....just using that buffer tube/buffer and spring.

Taking it a step further and modifying a 5.45 bolt w/ less aggressive lug angles is the ultimate in tuning the CMMG RDB.....rather than trying to tune the gun by just adding more reciprocating mass which just makes the gun more bouncy.

This is analogous to changing the locking piece of the MP5 to a #28 (80 degree).....IMHO, is the better way to deal smoothing the gun out...not adding mass.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Even so, the more you try to smooth out a 9mm M16, the more the cyclic rate goes up. I know many probably don't care about that but I do. Being straight blowback they also won't suppress as well....which I care about and obviously some people don't.

IMHO, having less recoil in a 9mm SMG than an M4 is not that impressive....again having less recoil than an MP5 is impressive.

Don't know if any of you have seen this thread: https://www.ar15.com/forums/AR-15/DPM-Recoil-Reduction-System-vs-Hydraulic-buffer-EDIT-Armament-LARB-Mod-2-and-3-added-to-the-test-/118-744494/?page=1

We are actively working on testing an accelerometer to give quantitative data to go along with subjective data in terms of recoil. I am also doing high speed video (1000 frames per second) of a cut out buffer tube to watch the buffer and spring.

In the videos you can see how much the gun kicks and the forward momentum of the gun from the BCG/buffer/spring going forward. I've got some ideas to lessen that....


Here is a MK18 with the standard 'milspec' configuration - .070" gas port, H2 buffer, standard spring (white sprinco).


Now here is the 9mm CMMG with the CMMG recommended buffer/spring configuration. Firing was done from a lead sled, strangely, it would run 100% from the shoulder but would jam in the sled....
Again better than straight blowback but not MP5 smooth.


Now my preferred configuration with my modified 5.45 bolt to optimize the delay for suppressed usage....since this bolt was optimized for 147gr suppressed usage, it doesn't lock back on the last round when a suppressor is not mounted and runng 115gr.
At the time, I forgot to put my 300BLK Tubb spring in there. It will lock back with that spring UNsuppressed....I'll do a vid of that next time.


I added the suppressor in this video.


You can see that there is very little rearward recoil impulse. I think this is MP5 smooth....
I'm going to do a high speed video of the same buttstock area firing the MP5 with the same ammo for comparison.
I am also going to do a few more videos with a straight blowback 9mm M16 w/ the standard Colt bolt weight, SAW tungsten bolt weight as well as some hydraulic buffers and the 9mm JP SCS.
I'm sure all of the straight blowback videos will clearly show more recoil than these videos.

However, as you can see in the other thread, I was hoping we could get the accelerometer dialed in so I could get data from that as well as do the high speed video at the same time as this is very time consuming to do all this.

Mantis also sent me their X10 to test for muzzle rise as well so will hopefully get data from that also.

My short pistol is 5.5lbs unloaded and 8.5lbs with 64rds on board.



My long setup is 6lbs unloaded and 9lbs with 64rds.


*Weights taken on a shipping scale that rounds up to the nearest 1/2lb.