It seems that the trend in firearms design over the last decade or so is squarely in the direction of monolithic aluminum uppers with MLok slots for accessories and steel reinforced inserts at the wear spots.

As far as I know, only Angstadt Arms as brought to market a roller delayed / modern MP5. And unfortunately the reviews don't seem all that good.

Of course, Grand Power's roller delayed SP9A3 isn't really the animal since it uses a roller in a completely different way from the way HK used rollers.

More complex construction and manufacturing.

For (IMO) little effective improvement.

So, you're saying it's a problem of the juice not being with the squeeze?

I think that's a perfectly reasonable business position to take, even if we can cordially disagree on it.

Modern manufacturing is making all kinds of things possible that were not possible just a few years ago. All the crazy converging turbine flow through suppressors for one example.

I’m saying that in the domestic marketplace within we exist, there’s not enough consumer interest in new roller-locked guns to justify the startup design and manufacturing costs.

Most people shooting 9mm's are cost driven. Blowback works for them.

Instead of just steel inserts, all the recoil absorbing forces must be made from steel. Aluminum does not respond well to repeated impact stresses.  Even those stresses on steel inserts will fatigue the aluminum support framework.

I figured we'd have a modernized MP5 or a Frankenupper of sorts by now.

Seems like the people that have tried, have tried to keep the AR upper receiver footprint and that's just not going to work.  You just need more space to work with.

Maybe PSA will make it work with the JAKL.

The LWRC attempt looks great, hopefully they'll continue to refine it and offer a 9mm option like they originally promised.

Right.  Like the CMMG Radially Delayed blowback where the bolt lugs are angled and are delayed when engaging the barrel extension instead of some steel inserts in what would be a proprietary upper.
Also, the new MEAN Arms bearing delay upper does the same thing with a proprietary extension.  Note that in the 2020 they introduced a roller delayed setup at Shot Show where the rollers would engage a proprietary extension for the rollers to engage.  Now they are hopefully about to release their 'bearing' delay soon.  They have an Industry section now: https://www.ar15.com/forums/Industry/MEAN-Arms-/817

https://www.ar15.com/forums/Industry/Bearing-Delay-Upper-Receiver-Assembly-updates-information-and-resources/817-303326/


I'm on the waiting list: https://www.meanarms.com/products/detail/reservation-for-bearing-delay-upper

https://www.ar15.com/forums/AR-15/MEAN-Arms-Bearing-delay-hopefully-really-happening-this-time-/15-778359/

I wouldn't get my hopes set too high.  "Ball detent" type firearm blowback delay has been around for 60+ years:
https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/3101648
In any case, best of luck to all.
MHO, YMMV, etc.  Be well.

What is your point?.... who cares how long it has been around...Regardless it has never been implemented in a 9mm M16 before.  Are you saying it isn't going to work?
I personally don't care if it is rollers, ball bearings or magic pixie dust as long as it works.

Based on the use of a "ball detent" to quell bolt bounce in .22LR full auto implementations, I am fairly certain a "ball detent" delay will "work".  However, in the Atchisson MkII/III .22LR full auto implementations, an $0.80, one ounce anti-bounce weight is a much more cost effective means of effectively quelling bolt bounce.  And in the Atchisson MkII/III .22LR full auto implementations, the "ball detent" has the additional system cost of being more difficult to install than an anti-bounce weight.  So the question is whether or not Mean Arms, Scheel, or any other entity can produce a "ball detent" blowback delay assembly that provides results commensurate to the total system costs vis a vis the alternatives.

MHO, YMMV, etc.  Be well.

ETA:  I've shot, but never owned a H & K MP5; however, 20 or so years ago I owned an H & K 91 for several years.  That roller-ramp ownership experience convinced me that I did not want an MP5.  Dropping a hydraulic buffer into an AR-15 lower receiver extension (aka buffer tube) is way faster, simpler, and fool proof.  IMHO, the total system ownership cost of a roller-ramp delay system is not worth it when compared to a currently produced hydraulic buffer such as those from KynSHOT and B & T.

not sure why you're so quick to.dismiss Stribog A3.
You're right, it's nothing like HKs' roller delay, but it is effective & much simpler and the pistol is still a few hundred less expensive than MKE clones.

The perceived recoil between my AP5 and A3 are so similar, and so much better than either my Scorpion or FX9,  that I'd say "job done"

Was thinking about trading in the scorpion micro for a stribog. Sportsman's Warehouse up near me has an A3.

I have a Stribog and love it. Don't get me wrong. It's excellent with the newer curved mags.

mine ran great with the straight, steel re-enforced mags, but I swopped out the lower with an aluminum Lingle for shits and giggles and dropped in a Rise 140 trigger cassette and the extended bolt release.
Necessary ? Not at all, but I do prefer the paddle mag release and ability to switch grips and triggers easily. And the extra heft feels good.

Who cares about it being implemented differently if it works to cut weight and recoil? Which it does.

I forgot to mention the JP-5 in this thread before:
https://jprifles.com/1.2.18_JP-5.php


Good article with info on it here: https://www.gunsamerica.com/digest/is-the-jp-enterprises-jp5-an-mp5-killer-deep-dive-part-2/

It even shares some of the guts with an MP5.
Very expensive.
I would have bought one if it was full auto compatible but it isn't because their ejector is like an HK lever ejector with the rear of it sitting right where the auto sear needs to go.  I confirmed with JP it will not work in full auto.
The upper and lower receivers are shorter than a milspec AR so you must buy as a complete gun.
So you are locked into their upper and lower receiver.  I think you can swap hand guards with whatever you want but note you will also be locked into Glock mags (which I don't like in a PCC / SMG).

There is also this current thread here: https://www.ar15.com/forums/AR-15/Which-not-blowback-9mm-AR-system-is-king-/15-779133/
The new Maxim Defense RDB was brought up: https://maximdefense.com/product/244978/


Drop in solution and for $189, I'm going to give it a try with my old 9mm Colt setup that is collecting dust.
I am anticipating that it will result in like 900 or so RPM in full auto which I don't want but I would think a lot smoother than any stock straight blowback setup with the delay and less reciprocating mass.
I doubt you will be able to tune it to get a slower cyclic rate like you can with the CMMG RDB or the JP-5 or the upcoming MEAN Arms bearing delay but again a step in the right direction and at a reasonable price if it works.

In a similar fashion, one could ask why doesn't anyone make a Blish delayed blowback device AR upper using monolithic aluminum uppers with MLok slots for accessories and steel reinforced inserts at the wear spots.  With modern zero lube surface treatments, there should be no need for the lube pads that the original implementation of the Blish delayed blowback device (i.e., Thompson submachine guns) had.

And, of course, the answer is the same - the cost/benefit ratio is unfavorable.  To wit, the British company, BSA, made a couple versions of 9mm (and other caliber) Thompsons after WWI, but only a few were ever sold and the manufacture of the firearms was discontinued.

MHO, YMMV, etc.

LWRC SMG-45 is not a delayed blowback gun at all. The company statements to that effect are a blatant lie. My personal theory as to why they insist of it is that their anchor customer was a government agency that wanted, roughly speaking, an MP-5 in .45 that takes UMP mags. So they wrote "delayed blowback" into the specs.

The LWRC subgun operates on a short recoil. It basically is a large Beretta 92 (or actually Arsenal Stryk, or other Bergmann system pistol). Oddball accuracy issues aside, it's a great gun that does everything an MP-5 does. But it's not a delayed blowback operated, so it does not meet the paper requirements.

So, what to do? LWRC simply called it "short recoil delayed blowback operated". Problem solved!

Someone just needs to make one in their garage so B&T can steal the design and charge us all $7000 for it.

How about gas delayed blowback?  Maybe a piston that goes in place of a gas key and protrudes through the reviever and barrel nut into a cylinder on top of a gas block?  HK P7 style.