Why no +P+ in a PCC?

On Winchester Ranger 127grain +P+ there is a warning not to use this ammo in a carbine or sub gun. Why? Isn't the bolt stout enough to handle this or is there some other reason? We're talking a 127 grain bullet moving out at 1250 FPS in a handgun length barrel. I'd love to see what it would do out of my Uzi's longer barrel, but I don't want to mess up the gun.

On most subguns there is no locked breech. The breech is locked by the foward momentum of an extremely heavy bolt and introducing overcharged ammo can upset the balance of spring pressure and momentum.

I would imagine a simple spring change on the roller of an MP5 would make it ok, but not in a Colt SMG or similar system. It would be a bad idea in an UZI.

I thought some of the 9mm sub guns were designed around pretty hot ammo?

Sure, some. Many others were designed around NATO 9mm ammunition, which I'm pretty sure includes the Uzi. Winchester's lawyers probably require the warning because of OOB detonations of other problems that might occur in SOME subguns. Especially those that fire from an open bolt.

For me, I have never cared for this +P+ stuff. If I was in a war zone I would want it, and a weapon made for it. But here in the peaceful Mid-West powerful ammo is just not a friend to my firearms. After all, I am at a range shooting an aggressive bowling pin at 25 to 50 yards. Why beat up a perfectly good firearm just to say I had the most powerful ammo in it?

True military firearms were usually made for the powerful stuff. But even with these firearms there have been issues. The US Army broke some Beretta pistol slides using some ammo that appears to have been grossly over powered even by military standards. Perhaps ammo and firearms makers remember that and shy away from the liability of the stuff. I just know I use mild ammo on guns that I want to keep for a long time. But that is just me....

I too was surprised to see that warning on the box considering that our department used +P+ in their MP5's... but that doesn't necessarily make it right.

H&K uses a roller locked breech system that can take quite a bit more pounding than other subguns. They also produce heavier springs for use with supressors due to for they change pressure in the barrel. I wouldn't be surprised if they have come out in recent years with springs tuned for hotter ammo too.

Makes sense, we switched to AR's a while back so I guess it doesn't matter anymore.

Yeah, that's what I thought. I kind of figured it would have something to do with an open bolt SMG. The thing that's scary is that Winchester specifically mentioned the UZI as a gun not to use the ammo in. I'm assuming that it would be the open bolt variety as there are no closed bolt fully auto Uzis out there available to Law Enforcement. The reason I'm asking is that my Uzi fed the ammo very slick. You couldn't feel the cartridge going into the barrel when I tried it (after loading up a 32 round magazine).

After watching the "Ghost in the Shell" movie I was a bit concerned about using high velocity/pressure ammo in a PCC.

The Beretta Storm can handle +P/+P+ ammo, but the manual warns that it might accelerate wear on certain parts (kind of a no-brainer IMHO).

The Marlin Camp Carbine was definitely not rated for +P ammo.

I've never seen documentation about such on the Ruger PC9 but, if I had to guess, it's so robust I would think it would handle it fine (but IDK).

I shoot +P in my Storm, no issues.

Indeed.

We broke our uzi at work with +P+....

Open bolt or Closed bolt?

Open bolt... It was a real No Shit IMI Uzi. The gov't depot gave us a choice of an MP5 or UZI for weapons training and familiarization. We got the Uzi and it last about 500 rounds of M882.

I wished some one would have given me that choice when I was in the SPs. I'm sure my daughter would have too when she was in SFs. But all she got was to go to Iraq. The only (other) full auto weapons that were at our range were privately owned by one of the CATM guys. He had a Mac 10 that for some reason or another went through ammo really fast... He had an M-60, M-1919, a couple of M-16s and a Mac10 (in .45). Remember, this was back in the good old days BEFORE the 1986 machine gun ban. I picked up a really nice barreled upper, collapsing stock, buffer and spring, and M-16 bolt carrier for $175. Those days are gone.....

Yes indeed - the controlling factor is the OPERATING SYSTEM and not the gun.

MP5 = LOCKED BREACH

Uzi, Colt AR 9mm, etc = "blowback" or non-locked breach. The ONLY thing holding the breach closed is the bolt's MASS.

The designer has to calculate that mass based on a given range of loads & their pressures. The SAAMI pressure for 9mm is 35,000 PSI or less and "+p" goes up to something like 38,500 PSI. "=P+" does NOT exist according to SAAMI - or put another way, "+p+" means: "more than +p" = but how much more is anyone's guess.

PLUS, the subgun designer figures that the 9mm ammo used will probably have a peak pressure spike at a late point on the pressure scale.

Some ammo (such as the AA 147grn 9mm competition load) has a very early spike & it will do very ODD things in an open bolt like an Uzi - such a ballooning the case head - which is right on the edge of a case-head separation (which will ruin your day & could be even worse for the guy next to you). It is fine in handguns with locked breaches, however. I have seen this ballooning effect first hand in the rental Uzi at the shop I once worked for. Luckily, no case heads let go.

I have a Ruger PC-9 that I hand loaded for, and I was pushing 115gr FMJs to 1423 fps.

The PC-9 manual states that +P+ ammunition is okay.

Just to add...

You all mention an open versus a closed bolt Uzi and their ability to fire +P+ ammunition. In an SMG platform that functions with an open bolt, you have a certain amount of inertia moving forward and the shell is normally fired during the forward stroke (pre-ignition like the Sterling). Things change in a closed bolt situation where you have no locking mechanism as in an MP5. A closed bolt Uzi relies only on the mass of the bolt and no forward inertia to work against the reward motion of the fired cartridge, giving the closed bolt system less ability to handle hotter cartridges unless there is an increase in bolt weight or of spring pressure. There is no forward inertia to work into the equation.

––-Catter

But on the other hand you reduce the chance of an out of battery firing with a closed bolt. I believe the Uzi they mention on the box of ammo refers to an open bolt design and not the closed bolt because most LEO guns will be fully automatic, and there are no Uzis that I know of that are full auto and fire from a closed bolt. However, I'm still not shooting the Winchester +P+ in my closed bolt gun. Too much bad that can happen and not enough good for me to justify using the ammo. Besides, I only have three and a half .50 caliber ammo cans packed full of loose 9mm standard pressure ammo as opposed to 450 rounds of +P+. That might be enough ammo, but I have a Dillon XL650 if it isn't.

If I'm not mistaken, doesn't the MP5 have roller locking?

Sorry, i mis-stated. I meant to say a locked bolt as in an MP5.

––-Catter

I shoot 45+P and 45 Super out of an Oly blowback upper. No isses so far.

I have had some case ruptures shooting major 9 loads out of my uzi, it appears the blow-back and extraction started while there was still enough pressure in the case to cause the event, it all went out the ejection port. I will be sticking with standard pressures on my blow back guns.

I have shot lots of +P+ out of both an UZI closed bolt semi, and a HiPoint 9mm carbine. Never an issue in either.
In fact, I bought some hot loaded 9mm ammo which was Israeli surplus, which I was told specifically never to fire in any pistol...but 9mm carbines were fine. Mixed military headstamps and dates, 1000rds in an ammo can loose. I probably put 500 rounds of that ammo through the Norinco UZI I owned. No problem whatsoever.
The Infamous Hirtenberger Hi pressure 9mm which was blowing up pistols was meant for Sterling SMG's (in cold weather).

You do realize that the real deal "UZI" brand "carbine only" ammo is pretty hot....

There is indeed another reason that has not been discussed. The longer barrel might increase the velocity above its desireable velocity. This could result in either reduced penetration, or, if the mushroom petals break off early, increased penetration.

Now, the other reasons discussed can also enter into it. Combine all the reasons, throw them in a bag with a lawyer, shake, and you get a statement like the one printed on the box.

I hadn't thought of that, but you're right. It seems that Ranger T might have a very small window in which to operate from, say 3.5 to 5" of barrel length.

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