Two M&P but one is more accurate?

The original M&P's were discontinued some time ago, around 2017 seems about right. Are sure it wasn't a 2.0, I've found the newer versions to be more accurate.

At any rate, even if they are the same gun it isn't unusual for gun "A" to be much more accurate than gun "B" even the same model. Especially with 13 years between production. The early M&P's, especially in 9mm had all sorts of issues which to their credit they did correct. The gun was originally designed around 40 S&W and the ones in that caliber worked much better.

The only thing we can say without inspecting them first hand is that no two guns are alike and each will have ammo preferences. Plus, there is the variable that we can't account for, and that is you. You might contribute to the accuracy issue. We just don't know.

My M&P 1.0 produced a pattern similar to a shotgun at 10 yards regardless of the ammo or shooter. Sold it and was glad to be rid of it. Really soured me on the M&P line.

My Shield, on the other hand, is a tack driver.

The early M&P 9 Compacts had a 1:18 twist and then they switch to a 1:10 twist.

I'm not sure but would assume the same would be true for the fullsize.

I've been meaning to ask the forum what's the practical difference of those 2 twist rates with regards to 9mm bullet weights.

A faster twist rate should be better at stabilizing heavier bullets - that's the deal with rifles.

Kart barrels are a 1 in 16 twist (I think) and they seem to stabilize most weights from 115 to 147 okay. If the M&Ps are producing large groups, it might be how well the barrel fits the slide and frame or the dwell time issue. There are several variables that could affect accuracy, so it's hard to point to a single thing and say that's it, unless one can do some tests to identify specific factors.

The 2.0 series specify a 1 in 10 twist. I think it applies to all 2.0s but I could be wrong.

Just for the heck of it, switch recoil springs and see how it shoots.

9mmepiphany said:

I thought they stopped production in 2017

Click to expand...

I've bought a couple of guns that were a year or two old but "brand new" in terms of use because they sat in a display case at the gun store.

I own an OD green Glock 26 that the owner of the shop gave me a 50 dollar discount on. He told me the gun had been in the case a year because no one liked the color.

9mmepiphany said:

I thought they stopped production in 2017

Click to expand...

S&W still shows the pre-2.0 versions on their website. Here's one example

https://www.smith-wesson.com/firearms/mp-9-no-mag-safety-le-0

I bought an M&P40c 1.0 last October brand new with night sights for $349. It shot OK but wasn't impressive accuracy-wise.

I bought another one, only with a safety and no night sights, brand new, in April or so. It was also about the same accuracy-wise.

And when I say they weren't very impressive, I am not talking about the typical gun owner that shoots at 7yds and declares a gun accurate cause he can get a 3" group with a mag full of WalMart ammo.

I bench rest all of my pistols at 25yds and work up about a dozen different loads in different bullet weights and powders in search of optimal accuracy and performance. I expect 2" or better at 25yds, and I can get it easily with my Glocks.

I ended up swapping the slides and frames of the two M&Ps so I had a frame with a safety and a slide with night sights. Was finally able to get the M&P40c to meet my criteria with under 2" at 20yds using a defensive load of 6.0gr of Ramshot Silhouette and 180gr XTPs.

Both M&Ps had different preferences for bullet weights, oddly enough. And I'm pleased that I was able to finally find a load that utilizes a heavy bullet and reasonable recoil with acceptable accuracy...

fxvr5 said:

A faster twist rate should be better at stabilizing heavier bullets - that's the deal with rifles.

Click to expand...

I'm not knowledgeable about twist rates....

Do you mean the 1:10 should stabilize heavier bullets better than 1:18?

danez71 said:

ohihunter2014 said:

So I shot a brand new M&P 1.0 9mm against my M&P 1.0 9mm that’s about 13yo with the same ammo and mine throws them all over but the new one purchased 2 weeks ago makes a ragged hole freehand. I dry fired it and the trigger feels a hair better than mine. Just curious what could be off with mine? It’s got a new recoil spring but I bet that barrel has 5-7k rounds through it. It’s also dirty. I tested it again and same accuracy result. Just curious what you guys think?

Click to expand...

The early M&P 9 Compacts had a 1:18 twist and then they switch to a 1:10 twist.

Click to expand...

M&P 9mm accuracy issue has been well documented and Hilton Yam of 10-8 Performance/Modern Service Weapons has done extensive testing and identified accuracy issues with certain bullet weights - https://www.thehighroad.org/index.php?threads/barrel-twist-rate-and-accuracy.780301/


M&P 9mm accuracy issues have been discussed at length on various gun forums.

Brian Enos - https://forums.brianenos.com/topic/231347-help-me-make-sense-of-the-mp-accuracy-issue/

S&W forum - http://smith-wessonforum.com/smith-wesson-m-p-pistols/451019-accuracy-coming-apex-m-p-barrels.html


From what I gathered, initially people thought accuracy issue was due to 1:18 vs 1:24 barrel twist rate but some others have pointed out the issues with the trigger and lockup of barrel as not all M&P owners experienced the same accuracy issue.

Having owned M&P40 and M&P45 and having done Burwell M&P trigger job, I can attest to gritty and heavy trigger pull of M&P 1.0 pistols. My M&P45 after the trigger job which produced around 4.5 lb smooth trigger went from a "Meh" average combat service pistol to "Nice" target shooter which produced 2" at 25 yards.

I think due to this reason, S&W updated the trigger on M&P 1.0 which was a significant improvement when I checked the new out-of-the-box M&Ps with improved triggers at the LGS. Check the trigger by dry firing while watching the front sight. Even though the two triggers may feel same, when the striker is released, one may move/jump the front sight more than other. If so, this could explain the difference in group size.

As to barrel lock up, push on the barrel hood and see if you can tell the difference between two pistols. If they both have the same barrel twist rate (check the bottom of barrel lug and if no dimple, it's the old 1:18 twist rate but if one or two dimples, it's 1:10 twist rate) but if one has tighter lock up, this could explain the tighter group.

And there is the barrel twist rate. My 9mm barrels range from 1:10 Tactical Kinetics to 1:20 KKM barrel with 1:16 Lone Wolf. With certain bullet type and weight, KKM barrel with slower twist rate produce the smallest groups test after test. With most bullet types in 115-124 gr range, group size are comparable with certain barrel producing slightly smaller groups than others. But based on my experience, I can't say whether twist rate of barrel alone could produce accuracy issue that M&P owners have experienced. In this post, Hilton Yam discusses use of 1:16 aftermarket barrel for his built M&P 9mm as compromise between barrel twist rates - http://modernserviceweapons.com/?p=4866

And Wilson Combat went from 1:16 to 1:10 for their match barrels.

To me, S&W going to 1:10 twist rate with even more improved trigger on M&P 2.0 is their answer to the M&P accuracy issue now producing accuracy better than most other factory pistols and why I suggested M&P 2.0 over 1.0 model - https://www.thehighroad.org/index.p...s-and-discussions.778197/page-9#post-10940688

Here's another interesting thread on the subject.

https://www.lightfighter.net/topic/mandampp9-barrel-saga

BC17A said:

Here's another interesting thread on the subject.

Click to expand...

Thanks for the confirming thread link.

Yes, I do believe barrel twist rate alone is not the cause of the M&P 1.0 accuracy issue. I think there are other factors like barrel lock up (Since your thread used the same pistol/trigger ).

OP in the linked thread getting consistent accuracy from KKM barrel with slower twist rate should throw a wrench in the move to 1:10 twist rate barrel. Maybe S&W should have just asked KKM to make their M&P barrels?

ohihunter2014 said:

I would put 17rd through one, lay it down and then pick up the other and do the same and out of 2 times the newer one stomped my older one.

Click to expand...

My guess would be newer M&P has better barrel, lock up and trigger.

ohihunter2014 said:

Jeb Stuart said:

Just for the heck of it, switch recoil springs and see how it shoots.

Click to expand...

I put a new recoil spring in mine in October 2018 but I put 1k rounds through it since then. I will try that and see what happens.

Click to expand...

I think this suggestion is to improve the consistency of the lock up? I would not consider 1000 rounds on M&P captured recoil spring "worn". So essentially, we could rule out lock up issue and look elsewhere.


BTW, are the accuracy results same for different shooters?

If so, then it's the pistol.

I believe if you have 1:18 non-dimple barrel, many posted S&W was replacing the barrel with 1:10 twist rate. Perhaps give that option a try?

If the front sight moves/jumps when you dry fire, you can try to polish the trigger parts or do the Burwell trigger job that will smooth out the trigger and lower the pull to around 4.5 lbs - http://www.burwellguns.com/M&Ptriggerjob1.htm

danez71 said:

I'm not knowledgeable about twist rates....

Do you mean the 1:10 should stabilize heavier bullets better than 1:18?

Click to expand...

in theory, yes.

I would give S&W customer service a call as this is a known issue.

Chances are they may likely offer you a 1:10 barrel replacement under warranty.

To improve accuracy further, you can address the trigger next. Polishing the trigger surfaces won't cost you anything but time. You can do part of the Burwell trigger job or all of it. I only did the sear modification and polishing of the trigger bar and it really smoothed out the trigger.