I have some questions about rifles chambered in 9mm...

For a rifle chambered in 9mm, would the AR15 or AK47 platform be a better option for reliability/durability in the long term?  Are rifles chambered in 9mm more reliable than rifles chambered in 223/556 and 7.62x39?

Barrel length - is there a optimum barrel length for 9mm in the AR and AK platform?

9mm ammo - Do rifles chambered in 9mm function and cycle better with a specific type of ammo and grain/weight?  Hollow point vs FMJ?

Your question is hard to answer because it's very general. I'm more familiar with the AR's available. AR's in general have more accessories available so if swapping stuff around is something you like to do they win out.

Are you looking for a SBR? Are you going to run a suppressor? If no 16" is the default and there is no reason to go longer. If yes there's plenty opinions that vary. I like super short stuff 4"ish because it's easier to keep stuff subsonic.

Bullet weight and load are gun specific. As a general rule lower powered loads can be trickier with blowback guns which is what most of these are. Like anything you might need to try a few.

FMJ will almost always be more reliable and feed better.

My guess is the AK holds up to more abuse long term.

Heavier bullets should create more back pressure and function better.

Bullet design HPT vs FMJ can both be reliable but a gunsmith may need to polish the feed ramp. The early generations of semi autos only liked ball ammo.

Thanks.

For barrel length, what would be the shortest length without going subsonic?  I'd like to keep it supersonic as close to rifle velocity as possible similar to 357 Sig 68gr loads that can go up to 2100 fps or would it be possible to just build an AR15 or AK47 chambered in 357 Sig?  Has anyone does it here?  I'm focusing on rifle velocity but in a lighter more compact rifle if that is possible.  I know there are big give and takes.

http://www.ballisticsbytheinch.com/9luger.html

Pretty sure I've seen a 357 Sig AR built. You are definitely getting into boutique category with that so I'd do as much research as possible and hopefully find someone who has done it. Trying to get a 9mm to keep up with the 357 Sig will always be hard.
https://www.ar15.com/forums/ar-15/AR-15-in-357SIG-/15-717441/

I saw a AK Draco or mini Draco chambered in 9mm which looked cool.  I'm just not sure if they're reliable or not.

At $40 a box of ammo it is a dying cartridge.  LE's are dropping it left and right and it really does not offer much performance over 9mm +P and once you start sending the bullets faster or slower than their performance envelope they stop performing terminally as they should.  Lucky Gunner did a good test on it awhile back.  There really is not good reason to choose the cartridge anymore.

Magazines for 9mm AR's exist. Is there a 9mm magazine for an AK?

They can use the same mags in some cases. PSA did AR's and AK"s that used Scorpion mags. Pretty sure I have seen glock mags on both.

As a general consensus, homemade 9mm AR’s tend to be the most finicky.  Factory build versions are more reliable.  

There are tons of factory AR, AK and other 9mm sub gun options.  My AR 9mm gets the least amount of love.  I shoot my PSA AKV, MP5 clones and Stribog much more with my Mp5 clones the clear winner.  All have been super reliable and are purpose built 9mm rifle type platforms.

Is getting a MP5 clone a better option than getting a AR or AK in 9mm?  Are MP5 clones more reliable than factory AR/AK 9mm's?

Which company makes the best highest quality MP5 clone?  Which ones do they use at Battlefield Las Vegas?

There have been reports of 9mm AKs from several different manufacturers cracking the rails.  In normal AKs, the bolt carrier rides on the thin metal rails.  In blowback AKs, the whole assembly is one bigass bolt.  And direct blowback 9mms keep the bolt locked by having heavy enough bolt.

I dont know if its the weight of the blowback bolt or the different angle that the operating forces act on it (normal aks are acted on at the top by the piston, blowback AKs are acted on lower at the breach face).  But for some reason, the blowback 9mm aks have had rails cracking more often than rotating bolt AKs.

It was a thing for the russian vityaz.  I have seen cracked rails from the romanian cugir modul ones, and even on an AKV.



I have an AKV and KP9 for 9mm AKs.  And a couple PSA 9mm ARs with different styles of mags.  I think the PSA ARV is probably my top pick out of them all.

Do you like the mp5? Ergos controls and trigger are quite different. They don’t have the need for a buffer tube which is nice. They are delayed blowback which can have advantages.

I do like the MP5.  Which companies make the higher quality MP5 clones?

As far as I know, all AK variants use blowback, which is primitive,  jumpy and gassy if suppressed.  

Most AR's are as well, but some variants are Radial Delayed Blowback, which is better in all those categories.

TBH, I think roller delayed Stribog is best path today, but if you want a big combat rifle form, I'd get the RDB AR.

Ron at Battlefield Las Vegas has said that on their MP5's they have to change recoil springs and extractor springs every 2-3 days.  I understand those are being used in a extreme way with a high volume of rounds.  But, would an AK or AR in 9mm have less maintenance than a MP5?  Which platform would need the most often maintenance or changing parts and cleaning?

I'm not in the MP5 fanclub.  I personally prefer the roller delayed Stribog (SP9A3 w/ SN>4000 w the curved mags, that is).  I have had none of that maintenance. But then, I'm only at 3000 rounds and not full auto.

My experience with the MP5 was a dissapontment.  Think of a German performance BMW - with the same maintenance needs issues.  

That, and with MP5 (and likely AK), here's hoping trigger pull #31 wasn't an important shot.  

Is there any long term data on the reliability/durability of AR's and AK's chambered in 9mm?  Are they more reliable/durable and have less part breakages than rifles chambered in 223/556 and 7.62x39?  Meaning, do the bolt carrier group and springs need less frequent replacing?

Do they use 9mm rifles at Battlefield Las Vegas?

I'm sure data exists but I really think you're overthinking it. Buy what you want and if you don't like it you can sell it and try the next one.

That is the logic of a seasoned gun collector.  I get the impression some buyers buy a gun under the premise that they will own it forever and fear it wearing down or becoming unreliable.  Folks who run guns hard have the understanding parts will break or wear down, and parts will be replaced in order to keep running.

I find that interesting because car owners understand parts will wear out and require replacement, but do not relate the same idea to firearms.

OP, I have a Frankengun AR9 SBR built on an Aero EPC lower with an 8.5" barreled upper. Uses Glock mags and runs flawlessly. The only change I made from a standard buffer tube kit was adding a heavier buffer.

It's in KISS mode & is my truck gun. The only gun I own that makes me grin more is my .308 M1.

I would not assume a 9mm blowback AK is more reliable than a 9mm blowback AR.

I've had both and had no issues but I have seen a few posts of people with 9mm AKs that have developed cracks on the receiver rails. It's not a common problem and was always after what I considered high round count, but was reported on both the PAK9 ( which I owned) and the NAK9.

9mm AR is at least non-proprietary, for the most part, vs AKs.

Used to own a Chiappa/Charles Daly PAK9 pistol that took Beretta mags, and several different AR 9mm uppers on a Hahn magwell adaptor and Metalform mags. Both were 100% reliable and reasonably accurate for a 9mm PCC.

But I can't say either was more reliable than a Scorpion Evo, Stribog, CX4 Storm carbine, etc.

If you’re worried about long-term durability, basically, all of the parts on an AR can be easily changed, but with HK and AK ,  swapping anything but the bolt or grip is hardly easy and requires specialty knowledge$$$

covered.

Being direct blowback, they have less small parts and less going on that could screw up compared to a gas operated gun.

In a normal AR, there's a gas tube.  The bolt and carrier are separate parts, where the bolt needs to rotate and lock into the barrel extension.  There are cam pins, and there are gas rings.  

In a blowback 9mm AR, is it impossible to have a blown out gas tube, or worn out gas rings, or a broken cam pin, or a lucking lug break off a bolt.

Here is a sub machine gun in 10mm...

Roller Delayed 10MM AUTO: The Perfect PCC? STRIBOG SP10A3...

What are the advantages and disadvantages to roller delayed blowback auto and semi-auto rifles?

Are direct blowback more durable/reliable in the long term over roller delayed blowback or the opposite?

Forgotten weapons did a really good video on the cmmg 10mm that went into this in depth. The roller delay is far more a thing for 10mm specifically. 10mm direct blowback doesn't work, so it needs some sort of delay or gas operation.

As i understand it, it's not an advantage in 9mm.

Reviewer is kind of annoying.  But I do appreciate the honest commentary on the venerated MP5 in his comparison.  MP5 is cool.  MP5 is wildly overrated.  And I concluded over a year ago I'll take a Stribog SP9A3 over an MP5, before we even get to price.  It's just a better and more modern gun.  And yes, Grand Power botched the initial release, botched several renditions thereafter; resulting in all the youtuber "Influencer" hate for the last 2 years - where they were all out of date, compared to a current SP9A3 SN>4000 with curved mags; which run like a swiss watch.

As to roller delay, yes, it makes a difference.  Even in 9mm.  Here's how little recoil someone who had been running a blowback Scorpion, experienced running a Stribog, while still mostly a rookie (meaning the video is demonstrating recoil in the hands of a non-pro).  The recoil of strong loaded 9mm is almost non-existant, and it's a very pleasant gun to shoot.  His post usage commentary was the Stribog was way more pleasant and lower recoil to run than a blowback Scorpion (Which, going to back to this thread title, is why I advise a pause on going with the AR/AK platform PCC - since most of those are still running primative blowback)

9mm Stribog in the hands of a sparse shooter.




Back to the 10mm Stribog video:
-he's right, MP5 is way overrated, and UMP is an embarrassingly bad step back for HK.  I once got to run a full-auto UMP45 and it was very easy to be hunting ducks very quickly with that POS.  Clearly the roller delay on the Stribog is huge;
-though the review never ran it without the supressor, which is a little dishonest and misleading - since supressors are great compensators too, and the 10mm has enough gas for that to actually start to show up in performance.  That, and I find youtube reviewes grossly overrepresent supressors in general, In a nation 330,000,000, about 300K actually have supressors - it's a tiny portion of the audience; yet sure as shit - every youtube-INFLUENCER has to run their supressor on everything.  That, and IMHO Supressors on small guns undermine the whole point of having a small gun - for the individual single-user shooter.  
-Reviewer was worried about offending people. - and he did, because the Stribog font is indeed FUCKING AWESOME! (big jerk)
-The complaints about the Stribog safety are correct, and easilyl corrected by the HBI safety for a couple of bucks.  Which are fantastic and I wish I had those on all my guns, because I love the way I can flip the safety back on with my trigger finger.
-His sighting system is a big goofy, people put too much shit on their guns.
-I'm less of a fan of the 10mm version magazine (stright, and 20 rounds only?  Why? - make it longer and at least hold 25, and curve it).  And the mag release / bolt release I prefer the 9mm versions.

As cool as the 10mm is, the problem with PCC10mm is it's going to cost a fortune to run, only holds 20 rounds, and still doesn't come close to competeing with a MK18 for power.  Not everybody gets free Influencer ammo.  The 9mm version is a complete blast, and mine has drunken many thousands of rounds now.  Nobody even lists it when it comes to PCC selection options, which is funny, because after running most all of them, IMHO, the 9mm 8" Stribog SBR'd. SP9A3 with curved mags, is the best SBR'd PCC 9mm out there (I can't comming on today's 16" versions - other than to say I think a PCCin 16" BBL configuration is pointless).  It's also one of the most cost effective.  

IMHO, the place for that gun is security detail discrete carry without a supressor with advanced technology hot armor piecing ammo.  You can discrete carry that gun better than Ronald Reagan's SS Uzi, and with a lot more 10mm power, and better than you can a MK18.

I think a sub machine gun in 357 Sig would be a good idea because of the newer Underwood 68gr Xtreme Defender ammo that has around 2200fps out of a 5" inch barrel.  Imagine it out of a 8" to 9" inch barrel.  That's rifle velocity.  It has less recoil than a 10mm.  It would be really effective with a 50 round drum.

At that point, why not just opt for a rifle in the first place? But it sounds really cool.

I think it depends on the specific use of the gun.  For longer range engagements out past 100+ yards than the 556 or 300BLK would be better but for under 100 yards indoors (CQB) I think hand gun rounds would be better in a sub machine gun.   Also, the light weight of the hand gun bullets compared to rifle rounds.

I talked to a former police officer at a gun store last month.  He said that for house clearing/CQB he would much rather prefer a sub machine gun in a hand gun caliber (9mm, 45acp, 357 Sig, 10mm) over a rifle round for a few reasons.  One of the biggest was noise/sound db.

For him the Mk18 was specifically developed, and with supressor was the whole point, for that whole mission.  For you and me, the noise, suppressor topic IMHO is more academic, because we're not on a fire team squad, and if I have time to retrieve and deploy a 2-handed weapon system, I have time to throw on a set of ear-pro.  And I'm solo.  For you and me, the flash-bang muzzle blast; while we have ear-pro on, is a mission enhancer, not a detriment. For the LEO, less so, as he is part of an assault fireteam, and that will deminish team members.  Hence, 5.56 10.3" MK 18 with supressor.

As to running a bottle neck round.  sure, you coudl do that - but if you are going to do that, why go with a fat pistol round at all - to with a P90, with 50 rounds.  P90 is an underutilized weapon system, IMHO; though for it to be pragmatic at all, it needs the short BBL and the full-auto trigger pack, which is lots of paperwork.

The problem with .357 SIg in, a SMG, is it's a weak bottle-neck round, at the same case diameter as a 10mm, in a weapon configuration where a slightly longer magazine length to hold the slightly longer 10mm round, is an irrelevancy (unlike in a pistol which fattens the grip).  It's just as fat, and so has the same magazine height, and height challenges.  If I have the choice between a.357 Sig and a 10mm in a roller-delayed SMG, I'm taking 10mm.  If I'm planning on running full auto, I might stick with 9mm... maybe.  Stribog needs to upgrade their 10mm magazine to more than 20 rounds, IMHO - pretty pronto.  If I want bottleneck enhanced speed in a barrel length long enough to actually use that, I'm going P90 BBL lengthed 5.7 (which is actually 5.56 dia), or I'm just going Mk18.  .357 SIG does makes more sense in a one handled pistol though, I think at least.

What about the Sig Rattler 300 BLK?  How does that compare to the MK18 in your opinion?

Also, on a separate topic regarding roller delayed blowback vs direct blowback which would be more durable/reliable for long term use in a submachine gun in 9mm/10mm?

Sig Rattler in .300 will certain fit the mission statement.  I'm one of maybe 2 guys here who doesn't really care for .300 BO, so take my commentary on it as non-representational - but sure, it will achieve the mission quite nicely, with excellent handling and performance aspects.   But then... if your goal is to send 230 gr of subsonic ammo in a CQB settting; .45 ACP SBR's are ready when you are - and don't have the Exploding Armamenatium Feature enhancement.
(actual photo I took from a recent range outing)

Of course, that won't be you, as only a retard would actua**KABOOM** (welll shit  - "Have Bill call me").

As to roller vs blowback life, I'm not actually aware of either really wearing out.  I don't know if Hnderson Defense posted on that in their high round count rental commentaries, to say.  I would imagine roller lasts longer, since it spreads the forces out, but I can't speak with any authority on that so maybe not.  The much venerated MP5 becomes a jamomattic if you don't do their special PM replacement regime on their extractor spring or whatever.  The multiple HK MP5's I've had chance to fire were jam-o-matics, probably over that. But That's a consumable issue, and they weren't actually worne out guns, per-se.

Has any companies been able to make a roller delayed system in a firearm that is more durable than the HK MP5 and fix the shortcomings/disadvantages of that system and not need to replace extractor springs?

So.. that's why we've been talking about the Stribog.  The answer with Stribog was.. well, a series of answers.

It was
No - it's a blowback
Then it was
Why Yes! now they have a roller delay  - but wait, no, because it was a beta-test designed roller delay that's a jamomatic POS.

Then,
Why Yes!  We fixed the bolt and now it's golden.   WE ROC...  well... .. wait, shit our straight mags dont' work... hang on
    OK curved mags will fix it! (Though really it's the lengthened feed lips as much as anything)

By now, all the youtube Influencers were shitting on Stribog with everything they've got.  Partially deserved since they were designing and redesigning on the go, and letting the customers test it for them.  But, thr point of the Imfluencer isn't to exert justice- it's to identify if this is a good gun now today, or not.  And today, some of them are still saying no - amd are wrong (today).

Then, with the roller delay, upgraded magazines, upgraded bolt.  It kind of got to be....
Well, yes..
   but not really because the US ammo is so weak, and our roller angle is set for hot Euro ammo.  

So.. we'll make a wimpy US roller

Then it was - well.  yes.  
I mean... kind of yes. because everyone's gunshy by now..

But... hmm.. .these thiings are running kind of great...

Actually.  Hang on... yes.  
This..
this is turning into a pretty damned hard yes.  

SWEET! We've got this bad boy down baby!  A solid reliable roller delayed gun with apparently a good lifespan that runs pretty F'ing great, under $1k, much lighter and more cost effective than an MP5; with a way more modernized form factor, controls, and LAST SHOT HOLDOPEN feature.  And railed top for sights, and a great feel. And a pretty good trigger.  This Gun ROCKS!....

And a sweet armbrace.  AHA!   We're HERE!



We're going to OWN this genre baby!  


And then
BANNED BY ATF.

God.... Damnit!

Or.. basically something like that.

(The only "Influencer" who got it close to right with a more recent unit, was GarandThumb.  but it's funny, you can tell he already had a negative bias, and he had a hard time really saying the thing was F'ing great; even though everything he did with it was F'ing great.  He didn't want to like the thing and you could see he was almost disappointed that it didn't suck.  because, in his own runs with it, it was F'ing great.  Of course, MAC completely shit on it and his advise on the Stribog is worth about as much as... well, anyway).

So basically, there was a brief window with Stribog that if you picked up their latest units with their latest mags; they are easily amongst the best, and absolutely THE best value for a 9mm SBR PCC (or basically, 9mm SMG).  That window was measurable in months, before the brace thing got banned.   But those who grabbed on in that window, won the lotto on 9mm PCC.  You can get one now, but it's a stupid 16" unit and apparently priced by the inch while at it.

Butttt wait!  With the injunction; you can still get an armbraced SP9A3 Stribog with an 8" BBL and a shoulder firing sweet stoc.... er.. "armbrace".   They'll eventually lose the injunction at the USSC level, but it's going to take years to get there - so the race is on; get one and see if you can wear it out before then.  

Let us know!

Very informative, thanks.

The Stribog SP10A3 looks very similar to the FN Scar.  Is the bolt carrier group in the SP10A3 similar to the FN Scar?

Also, how is the SP10A3's roller delayed system compared to the SP9A3?  Is it as durable and reliable?

Don't know any of that

Blowback AR is more reliable than AK. Blowback AR has more recoil than 5.56 and a lot less accurate too.

Me, my friends, and my coworkers all went Stribog roller delay.

If you want to spend a lot of money, it is between the APC9, MP5, and MPX. The MPX does not like to be suppressed. The MP5 requires top much maintenance, has too poor a trigger, no bolt hold open. The APC9 is Blowback with buffer.

For me, the whole point of 9mm is running 147 subsonic suppressed. It has the best terminal ballistics by running the Federal HST 147 grain. This ammo runs great in the Stribog. If you want supersonic get a 300 BLK.

I would say the round count of my 9mm AR with 7.5" barrel is somewhere between 15k to 20k rounds. Since it is a recoil operated gun, you do not need to worry about gas system or piston. Bolt also is massive (for a H&K MP5 you have to find someone doing maintenance on bolt from time to time). With a 9mm AR you have less parts that on the big brothers need maintenance (e.g. gas rings). There are less parts that can fail (e.g. gas tube). Sure there are parts that need attention but it is less effort to keep a 9mm AR running.

I have a ar9 with 16" faxon barrel and faxon bolt.. with stern mag adapter with p320/m&p mags.

I have zero issues with it..

I have about 9000 rounds thru it so far...

Using all reloaded ammo from lead 95gr rn to 147gr

At the time I built it I didn't own a glock or i would have went with glock mag adapter instead.