I recently purchased an M&P9 full size pistol and have been doing research on the various self defense rounds that are available. A high percentage of them are rated as +P rounds. In the owners manual it states “Plus-P” (+P) ammunition generates pressures in excess of the pressures associated with standard ammunition. Such pressures may affect the wear characteristics or exceed the margin of safety. Use of “Plus-P” ammunition may result in the need for more frequent service.

Can anyone please explain what kind of wear characteristics are implied that "may" happen and what service could be needed? What parts of the firearm will be most effected by the +P rounds in the 9mm M&P and what problems could happen using +P ammo?

I have no intention of using +P ammo as practice rounds beyond initial training with it and hope never to have to use it, but in the event that it would have to run the +P ammo I would like to know how it will effect the M&P9.

I would also like to know if the 9mm NATO ammo that is produced by Winchester will cause any problems if used as training ammo. My research states that it is rated somewhere between standard ammo pressure and +P ammo pressures.

I would like to stay with a 124 gr bullet. Any thoughts?

I use 124 GR +p gold dots in my m&p 9mm. In my opinion they are fine. I do stay away from +p+ however.

+P ammo stresses the gun a little more then regular ammo, and can cause accelerated wear on the weapon, sort of like a steady diet of .357 mags in a revolver as apposed to regular use of .38 target loads.

That said, +P ammo is loaded to safe industry standards (NOT so with +P+), and is safe in most any modern gun, unless specifically stated not to be by the manufacturer.

For occasional practice and carry use, you should have no problems. My M&P has limited rounds thru it, but I can tell you my Glock .9mm has had well over 10,000 rounds of +P ammo thru it without issue.

Larry

Do not sweat +P for carry, but it's not necessary. And never necessary for training. Onl4 of the 12 cartridges on this list are +P:

<------ Click the photo for the complete posting.

I normally carry .45ACP (the above photo should tell you why!) but when I carry 9mm it is Ranger T 147gr JHP (RA9T). My own experiences have me leaning to the heaviest bullet the pistol will reliable feed as heavy bullets have more momentum.

Note 9mm Parabellum in modern military form is 124gr (US M882 Ball is 124gr but NOT +P) but used to be 115gr. The heavier 147gr bullet may experience feeding problems in some pistols so testing is paramount. Ranger T feeds well in all my moderm 9mm pistols but not my old SIG P6.

-- Chuck

Hi jediknight, welcome to the forum.
Remember one thing, the Smith M&P9 was designed on the same platform as the .40 version, i.e. It's a .40 platform now chambered in 9mm. Therefore a limited diet of +P shouldn't hurt it! If your limiting your usage to just a couple if mags at the end of your traing session, the pistol should last for a long time!
NATO ammunition is another thing now! M882 was the load that initially broke Berettas!! It is rated at 1250-1275 w/124gr. FMJ, so yeah it's HOT! I've heard that it's been "watered down" and what is currently offered is running something like 1175-1200, so it should be ok.
As the foriegn surplus NATO stuff available: BE CAREFUL!!! Some of this is extemely hot!! Stay away from CAVIM or anything marked 2Z, "L7A1", and Hirtenbirger!!! This is true subgun ammo!
The recent Swiss stuff is really GECO and while warm (124@1250) it's wonderfully accurate, and it's what I run in my old folded slide SIG 226.
One last thing; What we call +P, the Europeans call standard pressure. So a box or two (to assure reliability) won't hurt!
If you want a great standard pressure round, I look heavily at the Federal 147gr. HST, and the 124gr. version. Dale

__________________
"Long live the S&W 3rd. Gen.!"

In essence, all the manual is telling you is that if you drive your car at high speed (or tow heavy trailers) all the time, it will need more frequent service than if you drive more slowly.

While the comments above about ammo are essentially correct, you should realize that SAAMI (essentially an American arms and ammo manufacturers group) decided to load 9mm at lower pressures than the Europeans do a long time ago. I strongly suspect the reasoning was largely political. Put another way, do you really think any company is going to produce something they can't sell worldwide? You should also be aware that law enforcement agencies are generally required to practice with the equivilent of their duty ammo. Given the number of agencies that issue (or did in the past) some variety of +P ammo, do you really think there is a major problem?

The need for more frequent replacement of the recoil spring, and possibly the trigger return spring would be the most likely result of a steady diet of +P. Since the replacement interval for the recoil spring is about 10K rounds, replacement at 5k under a steady diet of +P would be prudent. This would eliminate possible issues with battering as a result of excessive slide speed due to premature loss of spring tenstion. Recoil spring/guide rod assemblies are relatively cheap, the trigger return spring is a couple of bucks and I can't recall the replacement interval, but it's much greater than 10K rounds.

The parts exposed to being battered include, but are not limited to, the trigger block and it's contents (camming block and takedown latch and the block itself) as well as the slide. Those are the biggies.

Not sure if this is really the right answer, but I do remember reading an article by Robert Shimek on the Italian Glisenti pistol. According to it he said that the Glisenti was chambered for a low powered 9mm round that is identical to the 9mm Para in every dimension!
Thing was apt of G.I.s brought these pistols home after the war (WW2) and saw that 9mmP fit and began blowing the gun and parts of themselves up! Mr. Shimek said this is why American 9mmP is downloaded. Dale

__________________
"Long live the S&W 3rd. Gen.!"

Highly doubtful US 9mm ammunition would be underloaded for such a rare pistol as the Glisenti 1910.

The 9mm Glisenti cartridge is 0.2" shorter than standard German military 9mm Para but the pistol will shoot standard 9mm ammunition. It will not shoot 9mm Coto (AKA .380ACP) like the Beretta 1934.

According to my 1948 edition of Small Arms of the World "the standard German ammunition [9mm Parabellum] is unpleasant to shoot in this pistol and the high velocity ammunition developed for use in such weapons as the Machine Pistol 38, may be actually dangerous because of the excessive breech pressure developed."

The myth that standard European 9mm is more powerful than North American remains strong, however.

-- Chuck

That SAAMI and CIP have different pressure limits for 9mm isn't myth. However, I need to correct my earlier comments (thanks Chuck S) since I just now determined that since both entities are using piezo gauges, the limits for standard ammunition allowable pressures show SAAMI slightly higher than CIP (wasn't the case IIRC when SAAMI used CUP). However, this changes if NATO specifications are in play since NATO standards show maximum pressures higher than SAAMI in both standard and +P.

The pressures individual manufacturers choose to use is another matter. I recall a box of WW white box 115 gr. ball back in the 1980's that didn't clock 1000 fps at the match I bought it for. Shock to everyone involved (I still got credit for minor caliber since I had the receipt.).

BTW, S&W actually refers to what I earlier called the "trigger block" as the locking block since it acts as the recoil abuttement, locks the barrel into the slide and locates the slide assembly in the battery position. It's under $20 and is field replaceable.

Since we are talking 9mm.What is exactly the difference between Nato,Luger,Parabellum rounds?Will they work in all guns?

Luger* & Parabellum are different labels for the same item. 9mm NATO is the previous cartridge produced to a set of standards that were agreed to by the various military organizations of nations belonging to the North Atlantic Treaty Organization.

By developing a uniform standard, the weapons and ammo of all members would work in any example. Yes, you can use any/all of the above in any modern weapon in good condition.

BTW, studying US military specs just now, M882 ball is spec'd a few thousand psi under the NATO max pressure. That's wise considering the unknown climates the ammo may be used in. What raised my eyebrows was a spec for a subgun round that averages 38,500 psi and maxes in the 40Ks. There was a direction NOT to use it in the M9 pistol.

* I do believe "Luger" was attached by the importer of Luger pistols and the ammunition for same way back when (early 1900s) so both could be properly identified by consumers. There were (and still are) a slew of various european 9mm cartridges (Steyr & Bergman-Bayard, come to mind) that won't come close to chambering in a Luger P08.

WR Moore, Thanks for the info.Kenna

It's funny that you mention the Federal HST loads. The load I have been looking long and hard at it is the 124gr. version. I just haven't seen very many reviews of the standard loads, but have found tons on the +p loads and I wasn't sure how they would compare.

What else can you tell me about the GECO loads? I have shot the 124gr. FMJ from RWS which I believe is a Swiss manufactured ammo. I have heard mixed reviews because the round has some magnetic properties and some ranges are not allowing them. It sounds very similar to the GECO that you mentioned. I would like to use the same weight bullet for both my practice and self defence rounds.