9mm major in pistol caliber subguns?

#1
can these subguns on today's market withstand the extra pressure? speaking of the modern subguns we see today like AR9, Palmetto AKV9, Scorpion, Sig MPX, and one i was looking into running a Kriss Vector! i was thinking of a kriss vector to run the ammo if i could due to the recoil mechanism that alters some of the felt recoil..

or are 9mm major loads runnin just too hot?
 
#2
Not sure what is considered "major loads" but I mostly run 124gr NATO in my MPX (16in Gen 2) never had any issues. I like the NATO pressures because I know the extra pressures will always cycle the gun and the accuracy is good. I have also run most types of 9mm ammo through it from 115gr steel case FMJ ammo to federal 147gr HST. All that being said this is a sample size of one but I would wager that most others have similar results.
 

bkelly47

Newbie
Network Support I
#3
First is there even any factory 9mm Major loads? It’s going to be a bit hotter than +p+ loads so if the gun isn’t rated for +p+ I wouldn’t think about trying to run major ammo in a gun.

For instance +p+ Ranger Ts are ~157-158 powerfactor the minimum power factor for major in open is 165.

The ranger ts are 127 gr @ ~1250FPS to make major PF with the same bullet weight you would at minimum need to have the bullet go atleast 1300 to just meet 165 most people who load for major are going to be going to probably ~170 PF so they don’t get fucked over by environmental changes l.

I found Atlanta Arms makes a 9 Major load it’s a 147 going +/- 1180 FPS this makes a PF of ~173.5

Also most pcc’s excluding the mpx aren’t a locked breech so that throws another problem set in.

Basically No I wouldn’t try it. There are a few places making .357 sig barrels QC10 makes a 40/357 Sig/10mm bolt that would probably be the way to go if you want something with a bit more ass behind it than 9mm.
 
#4
First is there even any factory 9mm Major loads? It’s going to be a bit hotter than +p+ loads so if the gun isn’t rated for +p+ I wouldn’t think about trying to run major ammo in a gun.

For instance +p+ Ranger Ts are ~157-158 powerfactor the minimum power factor for major in open is 165.

The ranger ts are 127 gr @ ~1250FPS to make major PF with the same bullet weight you would at minimum need to have the bullet go atleast 1300 to just meet 165 most people who load for major are going to be going to probably ~170 PF so they don’t get fucked over by environmental changes l.

I found Atlanta Arms makes a 9 Major load it’s a 147 going +/- 1180 FPS this makes a PF of ~173.5

Also most pcc’s excluding the mpx aren’t a locked breech so that throws another problem set in.

Basically No I wouldn’t try it. There are a few places making .357 sig barrels QC10 makes a 40/357 Sig/10mm bolt that would probably be the way to go if you want something with a bit more ass behind it than 9mm.
yes there is another company that makes 9mm major factory loads as well with good reviews..but maybe the sig mpx may be the only one that can run the 9mm major loads..they do it john wick 3!

they say if a pistol has an unsupported chamber it is hazardous to the pistol to run it are you saying that for PCC's they need a locked breech to reliably run it?

do you think the kriss vector has a chance at all of running it?
 

David Mayeur

Regular Member
Network Support I
#5
The question is why?

9mm Major was developed for competition to meet power factor. PCC is minor scoring, so running 9mm Major has no advantage.

If you want to shoot Major PF loads, get a Kriss Vector in .45 ACP.
 

Joe _K

Established
Network Support II
#6
FWIW Mike Pannone was interviewed on a YT podcast, (not P&S) and asked what gun for home defense, AR-15, Handgun, or Shotgun, his answer was, None of the above, AR-9 Sub Gun 127gr +P+ JHP’s.
 
#7
The question is why?

9mm Major was developed for competition to meet power factor. PCC is minor scoring, so running 9mm Major has no advantage.

If you want to shoot Major PF loads, get a Kriss Vector in .45 ACP.
why would a 45acp vector be able to run major ammo but a 9mm kriss vector cant?..or are you just referring to 45 +P ammo?
 

David Mayeur

Regular Member
Network Support I
#8
why would a 45acp vector be able to run major ammo but a 9mm kriss vector cant?..or are you just referring to 45 +P ammo?
"Major" ammunition is a classification of power factor set by the USPSA rulebook.

Bullet Weight multiplied by Velocity divided by 1000 = Power Factor
165+ = Major Power Factor
125-164 = Minor Power Factor

Standard .45 ACP 230 gr FMJ is Major Power Factor.

The misunderstanding is that you think Major ammunition is greater than +P+, which is not always true.
 

David Mayeur

Regular Member
Network Support I
#9
9mm Major is a competition load to run a 9mm pistol and meet Major Power Factor.

What are you trying to accomplish with the Kriss Vector?

Here is a video for your reference on power factor:

 
#10
I think you've fallen prey to movie magic implications that 9mm Major is a special 9mm magic bullet that's more lethal than typical commercial 9mm loads.

The Vector's recoil management system won't make any difference in whether or not it can run 9mm Major PF loads, to my understanding. It doesn't really matter either, based on reasons previously stated. If it's for USPSA PCC division, you get nothing from using Major PF. If it's for home defense, it's far more important to get a reliable JHP load with consistent expansion and good terminal ballistics (Gold Dot, HST, Ranger T) than it is to add maybe another 100-200 FPS to a 147 grain bullet. If you want more punch than those will provide, go to a rifle caliber.
 

Default.mp3

Regular Member
#11
Something else to consider is that 9×19mm being driven to major power factor can actually decrease terminal performance. Modern duty bullets are designed to perform within a certain FPS range; driving them too fast will induce over-expansion and thus over-penetration. The only real advantage, IMO, would be hard cast bullets at major power factor for extreme penetration if barriers are the primary issue (or bears), which would be an extremely niche role.
 

Default.mp3

Regular Member
#12
First is there even any factory 9mm Major loads? It’s going to be a bit hotter than +p+ loads so if the gun isn’t rated for +p+ I wouldn’t think about trying to run major ammo in a gun.
Define factory. Underwood loads a few rounds to major power factor, but they're a boutique brand.
 
#13
9mm Major is a competition load to run a 9mm pistol and meet Major Power Factor.

What are you trying to accomplish with the Kriss Vector?

Here is a video for your reference on power factor:
when i say 9mm major i am referring to a specific type of ammo now in 9mm that is used for competition..however it is in fact a ammunition type now being manufactured as a specific load..they say as a disclaimer "competiton guns in open division" however im just thinkin well what if a pistol caliber subgun can reliably run major 9mm ammo..
 

Default.mp3

Regular Member
#14
when i say 9mm major i am referring to a specific type of ammo now in 9mm that is used for competition..however it is in fact a ammunition type now being manufactured as a specific load..they say as a disclaimer "competiton guns in open division" however im just thinkin well what if a pistol caliber subgun can reliably run major 9mm ammo..
Do you know why it's used in competition?

Have you found hotter ammo to somehow make the Kriss Super V work more effectively?
 
#15
I think you've fallen prey to movie magic implications that 9mm Major is a special 9mm magic bullet that's more lethal than typical commercial 9mm loads.

The Vector's recoil management system won't make any difference in whether or not it can run 9mm Major PF loads, to my understanding. It doesn't really matter either, based on reasons previously stated. If it's for USPSA PCC division, you get nothing from using Major PF. If it's for home defense, it's far more important to get a reliable JHP load with consistent expansion and good terminal ballistics (Gold Dot, HST, Ranger T) than it is to add maybe another 100-200 FPS to a 147 grain bullet. If you want more punch than those will provide, go to a rifle caliber.
well the 357sig is an ammo type that is loaded pretty hot and packs quite the punch from what iaccounts ve read..i think a 9mm 124gr loaded to push 1400fps has similar although likely slightly and i do mean slightly less terminal balistics..i dunno i think a pistol caliber subgun that could reliably run 9mm that hot wouldnt be a bad thing..
 
#16
Do you know why it's used in competition?

Have you found hotter ammo to somehow make the Kriss Super V work more effectively?
see now thats the thing the kriss likes the hotter ammo i have heard several ppl who own them say this..as it was built to be a high volume high rate of fire full auto sub machine gun..
 

David Mayeur

Regular Member
Network Support I
#17
when i say 9mm major i am referring to a specific type of ammo now in 9mm that is used for competition..however it is in fact a ammunition type now being manufactured as a specific load..they say as a disclaimer "competiton guns in open division" however im just thinkin well what if a pistol caliber subgun can reliably run major 9mm ammo..
9mm Major ammunition lacks the reliable performance required to meet accepted standards in terminal ballistics.

Do as you please, but you will not gain anything from loading 9Major in a Kriss Vector.
 
#18
9mm Major in subguns IS as awesome as it sounds. For a blowback AR, you can add more tungsten to the buffer, or replace the bolt carrier weight with a tungsten slug to increase mass if you experience case bulging or case head separation.

The "gold standard" for .357 Magnum one shot stops has been a 125gr hollowpoint moving at 1400fps. Decades of use in police and highway patrol as legend goes. Superb vehicle and auto glass penetration and field proven terminal performance.

.357 SIG was developed to offer that same 125gr at 1400fps. In reality, factory offerings chrono in the mid to high 1300's. Caveat is loss of capacity as the cases are .40s&w in diameter. Personally I carry .357 SIG out of a G27 because the case capacity yields more velocity in a subcompact versus a G26 with factory +p+ or handloaded major ammo. The slower powder of a major load translates to a gigantic fireball and negligible increase in muzzle velocity.

Making USPSA Major is 125gr @ 1320 fps min, or IPSC Major @1360 fps.

The extra 200 or so feet per second makes a world of difference in terminal performance.

Last thing to be mindful of is bullet selection. In theory a .357 hollow point will be engineered to expand optimally with the 1400fps+ muzzle velocity. A.355 hollow point "may" be engineered to expand optimally at 1100-1200fps which could yield fragmentation, lower penetration, and lower weight retention being pushed to 1400fps.

Brass Fetcher's 9mm Speer Gold Dot +p Gel Test:

Brass Fetcher's .357 Magnum Speer Gold Dot Gel Test:
 

Nate Osborne

NateMac
Staff member
Moderator
#19
Another thing to consider when wanting 9 major performance out of a PCC is the OAL of the round. I haven't seen a single USPSA open gun shooting 9 major using a load that would even fit in a standard pistol magazine (certainly not a Glock mag like the vector uses), much less chamber in a standard barrel. To get major power factor, you are filling a 9mm case with so much powder to the point where you can't safely seat a bullet to a standard OAL. Now, that is not to say it would be impossible to do, or that nobody has done it before, but I have not seen it. Perhaps a commercial loading outfit using non canister-grader powder build specifically for a 9mm major load could work something out, but I have already seen enough issues with 9 major, and that is out of guns build to shoot them.

I also have a variety of 9mm PCCs from 4.5-16" barrels. I think it is reasonable to assume that hotter ammo in a blowback gun requires a commensurate increase of bolt/buffer weight. Yes you can eek out a few more ounces by adding tungsten inserts inside the bolt, and using an extended steel buffer with tungsten inserts. I just don't want to be the one experimenting with it, and I certainly don't want to be shooting any large quantity of 9 major through am AR9 blowback gun. The Kriss, still being a blowback gun, is still bound by physics, and just because the weight is being directed down, doesn't change the fact that you need more weight to safely keep the gun in battery long enough, and the Vector isn't a bastion of customization when it comes to bolt and buffer weight.

It seems that you are looking for this project to become some sort of defensive gun. For me, at the end of the day a defensive gun must be reliable. I think this is the sort of idea where the juice just isn't worth the squeeze. All of this is just my opinion, so that that for what it's worth.

Finally, if you are really looking for a compact 'subgun' with greater performance, why not blackout? I have a 7" blackout that is a little lighter than the SBR vector, and about the same length with the stock unfolded. Then you get the supersonic performance that beats 9mm, major or not, by a long shot, is more reliable, and also gives you the subsonic option should you want that.
 

MrMurphy

Regular Member
#20
Avoid! Unnecessary! Exclamation! Points!

.357 Sig did so amazingly well that 2 of the major users, USSS and Texas DPS, swapped to 9mm.

If you want more performance than a shitload of 9mm on target in a hurry, get a 5.56mm SBR or .300 Blackout.

For indoor festivities a 10.5" AR is about as handy as an MP5, a bit heavier...with a lot more power.