Is early unlocking still a problem with the FS 9mm M&Ps? RANGE UPDATE

[Nakanokalronin]

Reading a response from my range report on another forum has someone mentioning early unlocking on the FS 9mm M&Ps. After doing a Google search, it seems many have gone with a Wolff guide rod and 20lb recoil spring to fix it which results in better accuracy. My M&P FS 9mm shot fine for me although I believe the groups could have been tighter than what they where so I'm not sure if this is still something that happens.

Anyone change out the recoil springs and guide rod with the type from Wolff and see their accuracy increase?

 

[TxM&P9]

I've read about that too. I thought they were for the older model M&P9 fs.

 

[Nakanokalronin]

I've read about that too. I thought they were for the older model M&P9 fs.

That's what I'm wondering. My groups where pretty good and should be even better now that I have the lighter pull,reset and break point due to the Apex sear. Once in awhile I did get a flyer so I'm just wondering if it still occurs in the current models.

 

[TxM&P9]

yeah, from what I could tell my groups are dead on. I'm not expert on barrel lock up but it seems pretty damn solid from when I rack the slide. Hopefully someone that knows will chime in.

btw. I'll take some pictures on my next outing with my compact an full size to share with yah.

John

 

[1sailor]

So as I understand it, the early unlocking was causing vertical stringing of the groups. And by increasing the recoil spring strength it allowed the gun to remain locked up longer allowing the bullet to leave the barrel before the slide would start back. Is that right? If this was a known problem has it been corrected?

 

[Nakanokalronin]

So as I understand it, the early unlocking was causing vertical stringing of the groups. And by increasing the recoil spring strength it allowed the gun to remain locked up longer allowing the bullet to leave the barrel before the slide would start back. Is that right? If this was a known problem has it been corrected?

That's the reason for the heavier recoil spring I believe. I hope someone on here knows if this has been corrected or not. Hopefully the thrown shots was due to the trigger pull which is where the Apex sear may prove it's worth.

The early unlocking seems to not have been in the .40S&W and 45ACP offerings, just the 9mm.

 

[TxM&P9]

I replied to you on glocktalk. It is a gun problem.

 

[clcdawg]

I have read about this issue before but my M&P is more accurate than I am. Since I shoot it better than a G19 I am not to worried about it anyway.

 

[Nakanokalronin]

I had a few off the wall fliers but it might have been more about the trigger than any barrel issues. After dropping in the Apex sear, the trigger travel is shorter and smoother, reset is shorter and more noticeable and the pull is lighter by at least a pound.

I'll try and get to the range again soon to see how things go, but so far so good. The most accurate ammo out of my FS M&P was the 124gr.+P PDX-1 which kind of surprised me since it's less accurate in my other 9mm offerings. This makes me think I don't have the premature unlocking syndrome but I'd like to be aware if anyone else notices it or if S&W has said anything about it.

 

[MichiganScott]

The relieved firing pin hole in the breech of the M&P would suggest that S&W is well aware of how the pistol unlocks. I suspect any premature unlocking was a trade off for 100% functioning. These are combat pistols, not target guns.

 

[Badkarma 1]

One way to check if your getting a premature unlocking is to inspect the spent casing. Look at the primer, see if there's a vertical mark left by the firing pin. Then it's unlocking early!
You gotta remember the M&P was designed as a .40 first, 9 second, and unlike vicea versa (where the early .40s were actually modified 9mms), Smith had to "detune" the pistol for the lighter 9mm.
Personally though I'd like to know how there running with a 20lb spring though?! Dale

 

[WR Moore]

I'd like to see documentation of a "problem" rather than someones opinion as to why they shoot poorly. Preferably citing measured times for various designs to unlock for comparison. There was considerable engineering work on the M&P series and as someone noted, it was originally designed as a .40 S&W.

Very short version: development of the .40 S&W cartridge required design changes to increase the dwell time-the time the barrel & slide remain locked together-in existing pistol designs. Since the M&P9 shares the recoil spring, locking block and barrel cam designs of the M&P40 (has a very slightly lighter slide) it pretty much has the same dwell time.

In a great many pistol designs based upon the classic Browning systems (like the M&P), the barrel & slide remain locked together as the slide moves rearward in recoil until the cam on the bottom of the barrel meets the cam on the locking block. At that time, rear of the barrel is pulled straight down. to unlock from the slide.

Any protrusion of the primer due to cratering or expansion into the firing pin/striker hole will result in the protrusion being shaved off. In extreme cases, it can lock the barrel and slide together like a pin in a socket. The tear drop relief at the bottom of the M&P striker hole is meant to provide a camming surface for any primer protrusion to prevent malfunction and minimize metal shavings in the firing pin tunnnel which may result in misfires. So, "strange" appearance of the primer compared to a hammer fired design with a different breech face doesn't prove anything either. (S&W also thoughtfully provided a debris drain so that the action of the striker shovels metal shavings and powder residue out of the firing pin tunnel. It isn't mentioned in the manual for some strange reason, cleaning it along with the striker tunnel is a real good idea.)

Most striker fired designs show some signs of striker drag. Recall that the inertial firing pins common to hammer fired designs are spring loaded to move to the rear. Striker fired designs are spring loaded to drive the striker forward so that they can fire. Yes, there may be a retraction spring, but it's nowhere near as strong as the preload spring on an inertial firing pin or the strikers firing spring. Comparing primer marks between the two different designs doesn't demonstrate anything but the difference between the two designs. You certainly can't use it as a method to diagnose 'premature unlocking'.

Walk around a range and look at some primers from competing pistol designs. Glock typically produces a coffin shaped primer mark showing where the primer expanded into the rectangular striker hole. Striker drag marks are also common.

About heavy recoil springs- I don't have figures on the M&P design, but the 1911 with the standard 16 lb spring had slide impact loading of about 700 Gs in recoil and 750 Gs going into battery while stripping a round. Recall that the forces going into battery are being stopped by the take down lever. And you want to increase the load on the take down lever????????????? 20 lb and up recoil springs had a surge in popularity in IPSC back when. Sheared barrel underlugs and slide assemblies launched downrange had a similar surge.

Those who suggest their technique may be the root of bad groups probably have the best grasp of the situation.

 

[Blue'87GT]

One way to check if your getting a premature unlocking is to inspect the spent casing. Look at the primer, see if there's a vertical mark left by the firing pin. Then it's unlocking early!
You gotta remember the M&P was designed as a .40 first, 9 second, and unlike vicea versa (where the early .40s were actually modified 9mms), Smith had to "detune" the pistol for the lighter 9mm.
Personally though I'd like to know how there running with a 20lb spring though?! Dale

FWIW, my .40 full size showed signs of this verticle marking on the primer with the few rounds (~150 rounds) I shot prior to returning overseas. (I only got to shoot for one day--it's in storage for the next year) It was still more accurate than I was. Is this something that I should return it to S&W for? BTW, this was with Winchester white box ammo.

 

[Nakanokalronin]

One way to check if your getting a premature unlocking is to inspect the spent casing. Look at the primer, see if there's a vertical mark left by the firing pin. Then it's unlocking early!
You gotta remember the M&P was designed as a .40 first, 9 second, and unlike vicea versa (where the early .40s were actually modified 9mms), Smith had to "detune" the pistol for the lighter 9mm.
Personally though I'd like to know how there running with a 20lb spring though?! Dale

Here's four cases from my first range trip....

 

[WR Moore]

Blue '87GT- Take a real good look at your breechface when you get back. I expect your primers are entirely normal for an M&P. Fired primers in the M&P are not going to look like fired primers from your M4, M9 or anything else that's hammer fired.

Thanks for your service and watch your 6.

Nakanokaironin-your pictures won't load, at least with my current settings.

From previous post:Most striker fired designs show some signs of striker drag. Recall that the inertial firing pins common to hammer fired designs are spring loaded to move to the rear. Striker fired designs are spring loaded to drive the striker forward so that they can fire. Yes, there may be a retraction spring, but it's nowhere near as strong as the preload spring on an inertial firing pin or the strikers firing spring. Comparing primer marks between the two different designs doesn't demonstrate anything but the difference between the two designs. You certainly can't use it as a method to diagnose 'premature unlocking'.

 

[Blue'87GT]

Blue '87GT- Take a real good look at your breechface when you get back. I expect your primers are entirely normal for an M&P. Fired primers in the M&P are not going to look like fired primers from your M4, M9 or anything else that's hammer fired.

Thanks for your service and watch your 6.

WR-Good point, I'll give it a look when I'm home next. Can't wait to have it in my hands again! Thanks for the last line--will do!

 

[Nakanokalronin]

Blue '87GT- Take a real good look at your breechface when you get back. I expect your primers are entirely normal for an M&P. Fired primers in the M&P are not going to look like fired primers from your M4, M9 or anything else that's hammer fired.

Thanks for your service and watch your 6.

Nakanokaironin-your pictures won't load, at least with my current settings.

From previous post:Most striker fired designs show some signs of striker drag. Recall that the inertial firing pins common to hammer fired designs are spring loaded to move to the rear. Striker fired designs are spring loaded to drive the striker forward so that they can fire. Yes, there may be a retraction spring, but it's nowhere near as strong as the preload spring on an inertial firing pin or the strikers firing spring. Comparing primer marks between the two different designs doesn't demonstrate anything but the difference between the two designs. You certainly can't use it as a method to diagnose 'premature unlocking'.

Shows up fine but try coping and pasting this link in your browser: http://desmond.imageshack.us/Himg708/scaled.php?server=708&filename=dsc01819c.jpg&res=landing

 

[Nakanokalronin]

Are the pictures of the cases showing up for anyone?

 

[Aahzz]

I see the pics fine.

 

[WR Moore]

OK, got home and used another computer. Those are entirely normal primers from the M&P. We adopted the M&P in early 2006, I transitioned to the weapon in April and picked up my personally purchased one in June(?). I'm also an instructor, I expect I've seen ~600K rounds go down range since then with our .40s. Less with my 9 since I'm buying the ammo.

As noted previously, look at your breechface. I've seen empties fired in M9s that didn't look that much different. If you're basing your expectations on .45 ACP empties, remember the 9 & .40 operate at over twice that pressure. Then there's the difference in firing mechanisms.

 

[Nakanokalronin]

Got back to the range today and here are the results.

This is honestly the best target when benching the FS M&P 9mm.

5rds/S&B 115gr./15 yards/benched

The next two target are from off hand shooting with slightly quick, consistent trigger pulls. I actually seemed to be able to get better groups this way and shockingly enough, the Tula (I wrote Wolf on the paper) ) was the most accurate. Although none of it is even slightly impressive, I guess it like the grungiest ammo the best.

16rds/Tula 115gr./15 yards/offhand

15rds/HST 124gr.+P/15 yards/offhand

The Apex sear did help with the trigger over stock and may have helped a tad with offhand shooting since there were no fliers. I've shot plenty of poly guns like XDs and Glocks, DA/SA pistols galore and many many SAO semi-autos like 1911s so I don't think it has anything to do with my shooting or trigger control when it comes to the accuracy of the FS M&P 9mm.

 

[TxM&P9]

The M&P9fs should be grouping a lot better than that at 15yards. Are you blaming the gun?

 

[Nakanokalronin]

The M&P9fs should be grouping a lot better than that at 15yards. Are you blaming the gun?

Well, I've owned probably 50+ handguns in my lifetime, many of them striker fired poly guns and I've gotten better groups using the same type of ammo. I also benched it so until someone has a ransom rest I can borrow, I can't do anything else other than what I've already done. I can get 4" groups or less with a 1911,XD,Glock,Sig,CZ, Ruger P-Series,Beretta, S&W and Ruger revolvers, BHP, etc so I would say it must have something to do with the gun since all those guns have different types of triggers and configurations.

 

[TxM&P9]

Well, if that's the case I guess I'll give you the benefit of the doubt. Have you thought about sending it to Smith? I just shot my 9fs today and did 3-4inch off hand @ 15yards. I know I can do better than that, thus it's me not the gun.

 

[Nakanokalronin]

Well, if that's the case I guess I'll give you the benefit of the doubt. Have you thought about sending it to Smith? I just shot my 9fs today and did 3-4inch off hand @ 15yards. I know I can do better than that, thus it's me not the gun.

I'm thinking about it. I may wait until Monday and call them to see what they find acceptable grouping and what method they use to test fire their guns for accuracy. I'll make sure to mention that I've shot 7 different brands of ammo with the same results.

 

[lamrith]

Do you have access to a video camera like a gopro? Might be nice to send them a video of shooting and how you have it on a rest etc..

I have fired 2 FS m&p and one compact all freestanding and they all made tighter groups than yours is showing off a bench. I would send yours back, something is obviously wrong, that wide of a spread off a rest is not good.. I did see a thread someplace about some .22's that the barrel was not fully finished, after 75rnds it started shooting all over the place..

This is from my new m&p9fs, 1st day shooting it yesterday. I have only personally shot 150rounds prior to this thru rental guns as evidenced by the strays I pulled way low jerking the trigger.
17rds sets/Remington 115gr. fmj/8 yards/freestanding

 

[Nakanokalronin]

Do you have access to a video camera like a gopro? Might be nice to send them a video of shooting and how you have it on a rest etc..

I have fired 2 FS m&p and one compact all freestanding and they all made tighter groups than yours is showing off a bench. I would send yours back, something is obviously wrong, that wide of a spread off a rest is not good.. I did see a thread someplace about some .22's that the barrel was not fully finished, after 75rnds it started shooting all over the place..

This is from my new m&p9fs, 1st day shooting it yesterday. I have only personally shot 150rounds prior to this thru rental guns as evidenced by the strays I pulled way low jerking the trigger.
17rds sets/Remington 115gr. fmj/8 yards/freestanding

My local range dosn't allow cameras in. You can't even have your phone on while shooting. Pretty dumb but they make the rules.

 

[lamrith]

WOW, that is pretty lame no camera's. I am sure it is for a reason. Maybe stops people from wanting to do and film stupid moves/actions..

15yrd is beyond what most will consider SD/HD range, BUT I think it should still group tighter than what yours is showing. I have not shot a handgun out at 45-50ft, the next time I go I will get a different target and give it a try.

 

[WR Moore]

There's another thread running about a lack of accuracy, at least in some examples.

Both have mentioned benching. Charlie Petty's noted in print that it's possible to blow groups with poor trigger control in a Ransom Rest. While testing new ammo earlier this spring, I inadvertently proved it's possible to blow groups from a benched rifle with artificial support at fore end and butt. I even re-bedded the rifle action before I realize the problem was the nut behind the trigger. A meeting with myself and a concentration on fundamentals, with a couple of changes in what I'd been doing solved the problem.

I will note that while I don't have personal experience with the ammo you've been using, I'd suggest trying some other brands just in case your M&P is prejudiced against those brands.

Having said that, every once in awhile a pistol ends up doing somewhat less well than most. That's where the lifetime warranty really shines-although you might want to take the aftermarket sear out if sending it in.

 

[stevet1]

I'd like to see documentation of a "problem" rather than someones opinion as to why they shoot poorly. Preferably citing measured times for various designs to unlock for comparison. There was considerable engineering work on the M&P series and as someone noted, it was originally designed as a .40 S&W.

Very short version: development of the .40 S&W cartridge required design changes to increase the dwell time-the time the barrel & slide remain locked together-in existing pistol designs. Since the M&P9 shares the recoil spring, locking block and barrel cam designs of the M&P40 (has a very slightly lighter slide) it pretty much has the same dwell time.

In a great many pistol designs based upon the classic Browning systems (like the M&P), the barrel & slide remain locked together as the slide moves rearward in recoil until the cam on the bottom of the barrel meets the cam on the locking block. At that time, rear of the barrel is pulled straight down. to unlock from the slide.

Any protrusion of the primer due to cratering or expansion into the firing pin/striker hole will result in the protrusion being shaved off. In extreme cases, it can lock the barrel and slide together like a pin in a socket. The tear drop relief at the bottom of the M&P striker hole is meant to provide a camming surface for any primer protrusion to prevent malfunction and minimize metal shavings in the firing pin tunnnel which may result in misfires. So, "strange" appearance of the primer compared to a hammer fired design with a different breech face doesn't prove anything either. (S&W also thoughtfully provided a debris drain so that the action of the striker shovels metal shavings and powder residue out of the firing pin tunnel. It isn't mentioned in the manual for some strange reason, cleaning it along with the striker tunnel is a real good idea.)

Most striker fired designs show some signs of striker drag. Recall that the inertial firing pins common to hammer fired designs are spring loaded to move to the rear. Striker fired designs are spring loaded to drive the striker forward so that they can fire. Yes, there may be a retraction spring, but it's nowhere near as strong as the preload spring on an inertial firing pin or the strikers firing spring. Comparing primer marks between the two different designs doesn't demonstrate anything but the difference between the two designs. You certainly can't use it as a method to diagnose 'premature unlocking'.

Walk around a range and look at some primers from competing pistol designs. Glock typically produces a coffin shaped primer mark showing where the primer expanded into the rectangular striker hole. Striker drag marks are also common.

About heavy recoil springs- I don't have figures on the M&P design, but the 1911 with the standard 16 lb spring had slide impact loading of about 700 Gs in recoil and 750 Gs going into battery while stripping a round. Recall that the forces going into battery are being stopped by the take down lever. And you want to increase the load on the take down lever????????????? 20 lb and up recoil springs had a surge in popularity in IPSC back when. Sheared barrel underlugs and slide assemblies launched downrange had a similar surge.

Those who suggest their technique may be the root of bad groups probably have the best grasp of the situation.

Excellent explanation of the locking procedure WR Moore. I also liked your last sentence identifying the problem on most likely being technique instead of mechanical. We all want to be good shots and all want that magic bullet out side ourselves. The gun is incredibly well engineered, the rest is up to us.