m&p 9mm accuracy issues

[9mmepiphany]

There WAS a documented problem with the very early Full Size 9mm M&P's (circa 2006). If I remember right it had to do with the twist rate....

I don't remember when that was fixed, but it has been quite a while.

There was never any other documented problems with accuracy on any other M&P model that I have read about.

I wasn't just the twist rate...although most of it was barrel related.

As I posted earlier, the M&P was optimized for the .40. The fit of the barrel wasn't great and the timing of the unlocking was off.

The earlier striker problem was addressed and the on-going slide stop problems just mandate shorter replacement intervals. The factory solution to the indistinct reset isn't optimal, but at least it is changed with every slide stop replacement

[Basscpa]

My MP shield 9 (CA compliant) needed a little break in period approx. 200 rounds. Compared to my XDs the fit and finish wasn't a good and the 200 rounds through the Shield completed the finishing job.

The accuracy was pretty decent when I did have issues it user error.

[2meterB]

not sure if this is 100% accurate to manuf date, but the included spent casing is 10/28/13, which is also printed on the box label.

[hossb7]

I agree that it certainly existed past 2006, and it may be more complicated than twist rate.

But it has been solved for a while, and only ever applied to Full Size 9mm M&P. That is my only point.

I just don't think it does anyone any good to blow it out of proportion.

Every company does things wrong now and then, S&W is no exception. They should have discovered and admitted to this much sooner, and made fixes available MUCH sooner.

Check out this post (I bolded the stuff to pay attention to):

http://pistol-forum.com/showthread.php?8743-M-amp-P9-barrel-saga/page7

Ok, so this was the sample:

Todd's Langdon barrel, 4 Storm Lake barres (2 drop in, 2 un-gunsmithed gunsmith fit barrels), and nine 9mm full size barrels.

The 9 M&Ps varied in accuracy as follows (aproximations), shooting Fed 9BP, WWB, Hornady 115, 124 and 147XTPs
#1 - >5" at 25yrds. Seems about average in my limited experience with these.
#2 - Hit 3.5" at 25yrds with 147XTPs. Wouldn't group less than 5 otherwise.
#3 - 8-10" at 25yrds. Patterns, really.
#4 - Would do 4" with the federal load, nothing else.
#5 - Same as #4, aprox a 4" gun.
#6 - Didn't matter what load, everything went into about 6".
Barrels 7 thru 9 were purchased separately from the guns.

What I learned:

1. Barrel fit is not the issue. One of the SL drop in barrels was machined to match the external dimensions of a factory barrel. Accuracy was only marginally reduced from as received.

2. Rifling twist rate is a red herring. First, 25yrds isn't far enough to generate that kind of inaccuracy based on twist rates. A poorly kept secret with pistol barrel makers is this: a smooth bore tube will shoot to ~1ish inches at 25yrds from a fixture. I really don't know how this got started.

3. Barrel timing/unlocking: this is where I had my money initially. I'd have lost my money. Take a G17 and a M&P side by side and compare. Slide travel for unlocking is nearly identical, as are most of the parameters that determine timing. Additionally, this was tested by increasing the recoil spring weight up to a factor of 2 with the most inaccurate pistols. No change in accuracy was achieved. Additionally, fired cases showed no indication of early unlocking (bulges, smears on the case head, etc).

4. Barrels were determined to be the issue by exchanging the 8-10" barrel with the 4" barrels. The crap barrel shot like crap no matter the gun it was used in.

So, back to basics. As with most baffling things about firearms, application of first principals yielded good results. If your gunsmith doesn't own a surface plate, he ain't a gunsmith. First thing done was to check the barrel dimensions. In each S&W case, the chamber was found considerably out of axis from the bore. The Langdon barrel and the SL barrels were all within 0.0005 round, and 0.002 front to back (meaning the axis for the chamber was offset less than 0.001" from the bore axis). The SL barrels had a tighter chamber than the Langdon barrel. Externally, aside from the S&W "frosted" finish on the Langdon barrel, you couldn't distinguish a SL barrel and a Langdon barrel with a micrometer. The 10" S&W barrel was 0.012" out of square with the bore axis. I plan on doing chamber castings of each of these for comparison. Again, application of first principals.

The 8-10" gun shot 2.5" groups with the Langdon barrel using 124XTPs.

While a larger sample size is needed to say anything definitive, I'd not worry about losing my lunch money betting the problem is with the barrel manufacturing process. In other words, the chambering and crowning process.

Todd - my apologies on the lateness of these results, I still have not had time to fully document the Langdon barrel, and therefore I haven't forwarded the findings to you.

Best I can do right now.

[J-cat]

An eccentric chamber will certainly ruin accuracy.

So what's wrong with the slides?

[Snagglepuss]

Are you muscling the gun too much? I noticed that with M&P's less pressure on the grip is more. when you squeeze too tight, your shots go all over the place.

I am not trying to say you have bad technique. Just try it a little different maybe?

[hossb7]

An eccentric chamber will certainly ruin accuracy.

So what's wrong with the slides?

They're heavily machined, which can introduce error when compared to say a Glock slide (that's just a bar).

Here's a good post that sums it up:

Bill has hit the nail on the head.

S&W has fully dropped the ball on this.

Bill has clearly identified the solution--an in-specification slide needed, along with a quality barrel.

The barrels are the easy part, as there are several high quality after market barrels available that work quite well.

The problem is the slide.

Fortunately, there is a proven vendor who has designed a superb M&P replacement slide and can go into production if enough orders come in.

I urge anyone who wishes to solve their M&P9 accuracy issues to contact Unity Tactical and let them know they want to order a Unity M&P slide. Also contact folks like Apex Tactical, Speed Shooter Specialties, 10-8 Performance and let them know you would purchase a Unity Tactical M&P slide if they offered them for sale. The slides can be made in stock form or with the ATOM mount for RDS installation.

Keep in mind that S&W uses the same frame for the 9 mm, 357 Sig, and .40 S&W M&P's. Thus if you already have one caliber and want to add another, you can simply purchase a slide/barrel assembly in the alternate caliber and drop it on the frame--much like swapping uppers on an AR15.

The last paragraph is especially interesting.

[smith and wesson]

It's much more complicated than that and extends past 2006.

Agreed I bought mine in 2012 and it wasn't accurate at all. I even sent it in for repairs. I ended up selling it. I came away thinking I need more practice w a handgun so I bought a 22 but in retrospect i fired a ton of rounds from the m&p and didn't seem to improve at all with it.