MPX performs doubles similarly to my fairly stock AR9? What next

[PigSnowball]

So I did the following test with my new MPX and my current AR9 build. AR9 just runs an 8oz buffer on a carbine spring.

https://www.youtube.com/watch?v=dzlfJ_2ljlI

 

Double tap at 15 yards, same ammo, tried my best to give as best of posture / control as I could on each.

 

Basically my AR9 was performing slightly better on double taps compared to the MPX. Considering the money spent on the MPX, I was hoping for more. Perhaps I'm not testing realistically, that my hold in competition really isn't as consistent as when I do this test and with weaker holds the MPX is going to outshine the AR9?

But... perhaps it's the hand-guard of the MPX? There's a lot of play in it out of the box. I sort of "shimmed" it using some hot glue in a few parts just to see if that would help, I think it did, but perhaps I need to get something more permanent. Perhaps I need to experiment with lighter / less perfect holds to compare between the two firearms?
 

 

 

[Nolan]

They are pretty similar under ideal conditions (grip & stance).  How are they under less than ideal conditions, ie.. on the move, off balance, leaning, etc...?

 

Nolan

[PigSnowball]

1 hour ago, Nolan said:

They are pretty similar under ideal conditions (grip & stance).  How are they under less than ideal conditions, ie.. on the move, off balance, leaning, etc...?

 

Nolan

I'm wondering what to test specifically that's repeatable actually.

I was thinking perhaps 3 targets, doubles on each. But that's really subject to the quality of my transitions,

Perhaps movement? double at 15 with forward movement. Do an average of a few drills to make up for the fact I might have pulled during a footfall.

Maybe stock on belt, beep double. Which will simulate having a realistic standing double with less than perfect mount rather than what I did in the video.

 

[Nolan]

I would do lateral movement, forward movement will have similar weight balance to your first test.  Then hard lean to the right, hard lean to the left and standing full upright with weight on heels (off balance).

 

Nolan

[ck1]

Checked out the vid... then watched your MPX/AR9 shots a few times at 0.25 speed... Not sure if you noticed, but you were standing just a little closer to the target with the AR9, and at 0.25 speed, it looks like the MPX moved a tad less (more a quick up/down whereas the AR9 went up/back and forth then down). IDK, looked to me like the MPX did better, bet if you'd fired the AR9 first before the MPX, the differences might've turned out to be more apparent (and/or once you've got more time behind the newer-to-you MPX)..? edit: Also noticed your support-arm looked more relaxed and less straightened out with the MPX vs AR9.

Edited February 4, 2020 by ck1
watched it again quick

[MoRivera]

This is a question I've had for a while...in that once an AR9 is tuned and matched to a certain load, with short-stroking et al, to the point where the muzzle rise is minimized and essentially the same as an MPX or CMMG Radial Delayed.....

 

Is the difference just the felt recoil impulse back into the shoulder?  In that respect I could see splits and groups being pretty close 1-to-1, and perhaps the increased recoil can lead to less consistency and just more work/strain over a string/course. 

[ck1]

15 hours ago, MoRivera said:

This is a question I've had for a while...in that once an AR9 is tuned and matched to a certain load, with short-stroking et al, to the point where the muzzle rise is minimized and essentially the same as an MPX or CMMG Radial Delayed.....

 

Is the difference just the felt recoil impulse back into the shoulder?  In that respect I could see splits and groups being pretty close 1-to-1, and perhaps the increased recoil can lead to less consistency and just more work/strain over a string/course. 

^^^ IMHO, I think you nailed it, the MPX’s recoil impulse is just lot more forgiving of when one’s mount/grip isn’t textbook. As an example: if you just hold an MPX out off your body and fire (even one-handed like a pistol) they actually cycle pretty darn similar to shouldering it. Blowback AR9’s, even well dialed ones, seem to move back and forth a bunch more...

The MPX route is definitely pricey, but comparatively, really dialing an AR9 like with the latest short-stroke JP SCS w/ a few or more tungsten weights to recoil almost the same way (but still not quite as soft) isn’t exactly cheap either lol  

[MoRivera]

Unfortunately, being a CT resident I can't buy an MPX, but I've been toying with the idea of building a CMMG radial-delayed based upper and running some appropriate Endomags.  I just wish there were more barrel length/profile options.  Might go with the 8" and then pin/weld a Taccom extension.

Edited February 4, 2020 by MoRivera

[PigSnowball]

6 hours ago, ck1 said:

^^^ IMHO, I think you nailed it, the MPX’s recoil impulse is just lot more forgiving of when one’s mount/grip isn’t textbook. As an example: if you just hold an MPX out off your body and fire (even one-handed like a pistol) they actually cycle pretty darn similar to shouldering it. Blowback AR9’s, even well dialed ones, seem to move back and forth a bunch more...

The MPX route is definitely pricey, but comparatively, really dialing an AR9 like with the latest short-stroke JP SCS w/ a few or more tungsten weights to recoil almost the same way (but still not quite as soft) isn’t exactly cheap either lol  

I might actually try some variation of this. I think it's pretty repeatable but perhaps will use two hands, but not actually shoulder it. See how each performs. That would cover perhaps the two extremes of form, my best possible form as in the video, vs worst realistic possible form, not actually shouldering the rifle.

[2011BLDR]

On 2/4/2020 at 9:27 AM, ck1 said:

^^^ IMHO, I think you nailed it, the MPX’s recoil impulse is just lot more forgiving of when one’s mount/grip isn’t textbook. As an example: if you just hold an MPX out off your body and fire (even one-handed like a pistol) they actually cycle pretty darn similar to shouldering it. Blowback AR9’s, even well dialed ones, seem to move back and forth a bunch more...

The MPX route is definitely pricey, but comparatively, really dialing an AR9 like with the latest short-stroke JP SCS w/ a few or more tungsten weights to recoil almost the same way (but still not quite as soft) isn’t exactly cheap either lol  

 

If you would put some effort in to tuning the gas in the MPX ( restricted / open plugs) and recoil springs ( +20%, stock, -13%, -25%) to your load you can see additional gains in reduced dot movement...

[biggulp]

MPX recoil impulse with any ammo will be more "forgiving" than any blowback gun with that same ammo. 

 

Does that matter when doing static drills with a perfectly tuned blowback gun?  Probably not, especially if you've got thousands of rounds behind the trigger with that blowback gun.

 

Does that matter when you're on the clock, running through a stage changing levels/distances/target types (mixed steel and paper)?  Absolutely.

 

Does that make the MPX absolutely superior to a blowback AR9?  Nope.  

 

 

[ck1]

3 hours ago, 2011BLDR said:

 

If you would put some effort in to tuning the gas in the MPX ( restricted / open plugs) and recoil springs ( +20%, stock, -13%, -25%) to your load you can see additional gains in reduced dot movement...

 

Totally agree. If I was reloading I might get into that. However, that said, from what I've seen at matches, I think specifically with the MPX playing with load/PF, gas, and/or springs is what's mostly responsible for them getting a bad reputation for poor reliability...  running factory stuff at 145-150pf the MPX still shoots as soft (or softer) as guys with blowback guns running 125-130pf. FWIW, I've seen a lot of issues and headaches occur when MPX guys start chasing the power factor floor, YMMV

[2011BLDR]

5 hours ago, ck1 said:

 

Totally agree. If I was reloading I might get into that. However, that said, from what I've seen at matches, I think specifically with the MPX playing with load/PF, gas, and/or springs is what's mostly responsible for them getting a bad reputation for poor reliability...  running factory stuff at 145-150pf the MPX still shoots as soft (or softer) as guys with blowback guns running 125-130pf. FWIW, I've seen a lot of issues and headaches occur when MPX guys start chasing the power factor floor, YMMV

Don't agree... as a closed gas system the MPX can be under gased or over gassed by sympley not understanding the burn rate and presser curve of the ammo iregardless of it being reloaded or factory..the stoppages will look the same ( empty case in action, next round not chamberd) this is a fail to eject in an undergassed situation or an extraction failure do to the case still being expanded to the chamber in an over gassed situation..

Factory 115gr can range from 1020 fps to 1490fps in a pcc... lots of info on tuning blowback systems around hear but everyone expects the MPX to run any thing and everything 100% all the time ...

I normally run speer 115gr TMJ that is 1400fps with .0520 restricted gas and 13% reduced recoil springs when I go to 115gr JHP @1400fps with 5.9gr of CFE Pistol I have to change to the .114 gas plug( factory Open).. when I use fed 115gr JHP +P+(9BPLE) @1450fps I need to go to a .0469 gas plug with the 13% springs.