OP
M&P M2.0 Accuracy Issues, do to dwell time?
- Thread starter Christopher67
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On my last trip to the range my first 5 shots were right on target--not low and left as usual. Guess it'll be going back to the Mother Ship to fix this problem!
Walt Sherrill
Member
Slingn said:
From what I've seen, it's most new striker-fired, polymer-framed guns which are being fired by folks who aren't used to striker-fired, polymer-framed guns.
They get over it.
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The M&P started out as .40. The .40 & .357 slides (so far as I can tell) are identical except for the roll marks on the sides. The 9 mm is very slightly different. The center rail at the breech end that picks up the round from the magazine is skeletonized to make inserting a full magazine easier on the .40 (assume same on .357). I'ts full length on the 9 mm. Also, the 9 mm has slight lightening cuts on each side of the slide forward of the ejection port. I've never had the opportunity to take comparative weights, but the difference can't be much.
Under load, steel can deform. Take a look at a flat bed trailer bed sometime both loaded & empty. If the design and material selection is correct, it resumes it's original shape when unloaded. In the case of a pistol slide, I'd expect any stretching to be virtually microscopic, if not nonexistent, and the tolerances elsewhere in the slide assembly & frame fit would make it insignificant. Randy's comments about the barrel squirming around in the slide for example.
I expect someone's mentioning the "issue" just to cover all theoretical bases (and their butt). Also sounds good as an excuse for poor groups actually caused by not properly performing all the fundamentals. I think a lot of the whining (not all) is from folks who hadn't/haven't adapted to the different trigger action of the M&P. They lose patience and finish off with a hearty yank.
Honestly, I've always been able to shoot better groups with better shot placement with my 9 mm than I was ever able to do with my issue .40, both being stock. When we were doing T&E, the S&W rep flatly stated that the 9 mm was the more accurate pistol.
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Rastoff
US Veteran
I respect your opinion and the value you've brought to this forum, but I have issue with this claim. Was he shooting from a Ransom rest? Was it possible that he just shot a nice group that was tight for him and used the "quarter" size not literally, but more to say that it was a really tight group? Maybe 2"?
Randy, I also respect your ability and what you've brought not only to this forum, but to the M&P world in general. I have your FSS in my M&P45 and it's amazing. However, a .3" group at 25 yards is difficult to believe, even from a Ransom type rest. Not that I don't believe you, I'm just amazed that it's even possible with this type of gun.
Also, I would like to examine the concept of the slide stretching. You mentioned a "few thousandths" of stretch. A length of .004" is visible. In the world of precision measurement, that's a lot. Of course there's a lot of forces involved when shooting a firearm. Not all of them are linear. I've never thought about the concept of slide stretching before. I'm not sure I understand how it would affect the POI. The barrel lug pressing on the take down lever pin seems more likely to cause issues. You wouldn't happen to have any drawings depicting what you're saying about slide stretching and how it affects accuracy, would you?
Have you actually measured this flex in the slide?
Fastbolt and Randy Lee,
Please understand, there are a lot of claims about accuracy on the internet. The vast majority of them are just fantasies in the minds of those who tell the tales. I have spent much time challenging claims and asked many who've made such claims to back them up with real targets. Very few have even tried and of those that try, even less succeed to validate their claims.
This discussion shows that y'all have put more thought into this than even the average precision shooter. I would love to continue this and learn more about it. Previously, my thoughts on dwell time were that the round has already left the muzzle. Clearly there's more going on that I took into account.
I've helped train and mentor this instructor since he came on the FTU staff about 10 years ago. He's really starting to get his sea legs as an instructor and a continuing student.
We don't do ransom (or other fixture) rests, and typical "accuracy" spot checks are normally done shooting 2-handed, standing, unsupported (just like most "regular" shooting"). Besides, the average out-of-the-box good quality pistol (and revolver) is generally going to be capable of more inherent accuracy than the average shooter/owner can realize as practical accuracy.
The last time he was exclaiming about the accuracy of one of his (constantly purchased) new guns was his 5" Pro 9, so I took him downrange and had him shoot some small wooden clothespins (which are rather narrow targets) at 7-10yds to demonstrate it (and his proficiency with it
). He got on a roll and hit several. Not bad.He's reached a point in his skills development where he's becoming increasingly able to equal (or exceed) what I can do when making called hits on the clothespins when we shoot together. He's either getting better ... or, I'm just getting old.
He's only in his mid 40's (20 years my junior). If nothing else, his eyes are better, even if I've got tens of thousands more trigger presses under my belt. I remember, close to 15 years ago, being able to use my 3913 and my first G26 (and a T&E P226/.40) to make called hits on the small round plates of the dueling tree, out at 90-95yds. (I think those are 6" plates, but I haven't used it for a few years.) It took some practice to be able to make the hits more often than not at those distances, but I could see the plates over the sights pretty clearly back then, even if I did have to adjust for elevation. Nowadays, I doubt I could easily see the plates at that distance with anything approaching "clearly". Bowling pins at 50yds, sure, because they're taller.
Anyway, as I commonly (reasonably) make him demonstrate his accuracy claims (and have made him do it in front of people attending classes, quals, less experienced instructors, etc), he's typically pretty careful about making such claims to me. I'm of the older "prove it" generation of LE firearms instructors.
Besides, we're only talking about a quarter-sized group at 7yds. That's pretty close. Also, a quarter coin is just barely under an inch in width (I just looked it up, and it's 0.995"). The relative size of the small POA/sight picture visible over the front sight at 7yds helps a lot. Now, going out to 10-15yds can really start to shrink that small of a POA, compared to the width of the front post, and groups often start to open up due to shooter influences, if nothing else.
Personally, having seen even my earlier production '08 vintage M&P 45 produce some more or less 1-hole shot strings at 5-7yds (when I'm doing my part), I expect him to improve over his initial quarter/coin efforts in shooting slow groups for accuracy at that close range.
Now, in the hands of a skilled precision competitive/target shooter, (Meaning not me.
), using something maybe a bit more accurate than whatever duty ammo was at hand? It would be interesting to see how the average M&P 45 2.0 does against the early model. Just for grins. If they make a PC/Pro version? Maybe really interesting.
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Randy Lee
Member
Rastoff,
I think skepticism is a good thing, especially in this age of mis-information.
The .3 inch group was witnessed by our design engineer and I would not have made that claim if it were not real. While we believe this was a perfect storm event, what it does show is that a polymer, striker fired pistol has a much greater mechanical accuracy potential than most people could have imagined. I added a picture of the actual group in one of the previous posts. Is it repeatable at that group size? I do not know. Probably not, but here are a couple of other groups that were shot from customer guns while we were developing the barrel. I also included a group fired through a factory barrel for comparison.
We also only make the claim that our barrels will provide 1" at 25 yards with our Gunsmith Fit barrel and 1.5" with our Semi Drop-in using quality ammo. That is because most people cannot shoot to the level of the a machine rest.
Attachments
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Jim Watson
Member
I am more interested in shootability than pinpoint accuracy.
I have a Plastic M&P with a full bull gunsmith action job that is very fine.
On the other hand, I have seen a number of guns with owner installed parts kits. They are highly variable, which does not surprise me, considering the materials and construction of the pistols.
So my Big Question is, what are the chances of getting an Apex Apex?
Do you foresee getting back into the starving gunsmith business or is parts sales what it is?
I have a Plastic M&P with a full bull gunsmith action job that is very fine.
On the other hand, I have seen a number of guns with owner installed parts kits. They are highly variable, which does not surprise me, considering the materials and construction of the pistols.
So my Big Question is, what are the chances of getting an Apex Apex?
Do you foresee getting back into the starving gunsmith business or is parts sales what it is?
Randy Lee
Member
I suppose one could use iterferometry to measure the stretching of the slide to get exact stretching measurements. Unfortunately, we do not have a lab with that degree of sophistication. I stumbled across the event by accident really.
The way I discovered the phenomenon was by viewing a high speed video of the gun being fired from the Ransom, and going through over 10,000 individual frames. It was in one frame that I noticed the phenomenon. In that one frame the front half of the slide was viewed with crystal clarity, but the rear of the slide from the breech area (actually rear of the ejection port) back was blurred. There was no gas escape present in the frame to obscure the camera. I even looked at the frame on a 70" HD screen to get a better view.
"The barrel lug pressing on the take down lever pin seems more likely to cause issues." You have hit the nail on the head. When the slide stretches, the forces holding the barrel in its vertical orientation change.
Randy Lee
Member
At some point in the next year, I will be doing gunwork on a limited basis.
Working on the bench is sort of therapeutic...
OP
Christopher67
Member
I would love to send you my M&P M2.0 9mm for a flat face trigger & barrel.
Please keep us posted.
Rastoff
US Veteran
The diameter of a US quarter dollar is .955", but what's .04" amongst friends?
Brother you don't have to prove anything to me. Your contributions here are well documented and an incredible asset to the forum. If you believe he did it, I believe he did it. I just raise my hand to ask because you and I have rarely seen 1" groups by someone shooting off hand at any distance. Tell me I'm wrong?Same goes for you Randy. If you say it happened, it happened. That's not going to stop me pushing those buttons.
As I've offered many, many times, anyone who thinks shooting small groups is easy, take my challenge: Rastoff's Challenge- Dropping the Gauntlet It's far easier than a quarter sized group at 7 yards, but so far I can count on one hand, those that have been successful, and not run out of fingers.
Oooohh, you said "interferometry", I love measurement. I'm a measurement geek and you might have the ability to actually make the measurement. No laser interferometer necessary.
With a high resolution, high speed camera, it would be possible to measure the size of the ejection port, frame by frame. A difference of as small as .005" is possible with this method. Also, if taken from the top, you could measure the straightness of the slide and how much it changes with the same set up. Just place a straight edge near the slide as it's fired. Then measure the distance from the straight edge to the slide frame by frame. Do this in at least three points. You could see exactly how much flex there is in the slide as the pressure is exerted.
Then you could also use strain gauges to measure this same flex. Strain gauges are super cheap, but very difficult to install. Also, you would need a data system with a high data rate to capture the event as it happens.
We do this kind of measurement all the time at Edwards AFB, but not usually at the speed necessary for this study. I would love to work with you on this. With the proper understanding of what's going on, you could revolutionize the semi-auto world.
Walt Sherrill
Member
WR Moore said:
It may not have to be much. That is exactly the area Randy Lee talked about when he noticed the "stretching" in the 9mm slide.
If that area is slightly thicker in the .40 and .357 SIG slides, that might account for a difference in slide performance/behavior.
The weight might not be different, given that another area in the .40 and .357 SIG slides was skeletonized. Weight alone wouldn't necessarily be a factor in slide stretch as much as where any extra material is located (or taken away).
(This is all conjecture, of course, but interesting conjecture.)
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I have an M&P Shield with DCAEK and Apex aluminum trigger, love that thing. Seeing the Apex brand grow from just a few products to what they offer today is amazing. Great job.
I do have a question though on the dwell time/early unlocking issue on the 1.0 M&Ps, was that only affecting accuracy on the 9mm models? What about the 40 S&W models?
I have a 1.0 M&P40 and am considering getting an Apex 9mm conversion barrel for it. I don't have the tools nor the knowledge to do a drop in, so I need to have a gunsmith do it. I wish Apex still had these types of services for sale.
I do have a question though on the dwell time/early unlocking issue on the 1.0 M&Ps, was that only affecting accuracy on the 9mm models? What about the 40 S&W models?
I have a 1.0 M&P40 and am considering getting an Apex 9mm conversion barrel for it. I don't have the tools nor the knowledge to do a drop in, so I need to have a gunsmith do it. I wish Apex still had these types of services for sale.
Walt Sherrill
Member
According to the Apex staffer (and the guy who designed the Apex barrel), it wasn't dwell time, but slide stretching that caused some variations in performance. The slide had less materials in the 9mm version than in the .40 and .45 slides, so those slides were apparently NOT subject to the stretch. All of this was explained in the discussion, with a good bit of technical explanation offered by Randy Lee of Apex.
You may have to decide whether the barrel will make a big difference, given a 1.0 slide. But none of this means that the Apex barrel won't improve your results.
(Note: the metal used in slides can stretch and return to it's pre-stretched state unless it's stretched too far -- but not all slides demonstrate that behavior.)
You may have to decide whether the barrel will make a big difference, given a 1.0 slide. But none of this means that the Apex barrel won't improve your results.
(Note: the metal used in slides can stretch and return to it's pre-stretched state unless it's stretched too far -- but not all slides demonstrate that behavior.)
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I did read the thread, skimming some parts but I read all of Randy's replies. However, in the Apex video where Randy talks about the production of the barrel, he says the Apex barrel "stabilizes and increases the dwell time" so you aren't seeing the POA/POI drifts. So according to this video, dwell time was an issue.
Either way, I basically just wanted to find out if the issue was only affecting 9mm, or if the 1.0 M&P 40 was also plagued.
Video here:
[ame]https://www.youtube.com/watch?v=sKz9QarKa80[/ame]
Either way, I basically just wanted to find out if the issue was only affecting 9mm, or if the 1.0 M&P 40 was also plagued.
Video here:
[ame]https://www.youtube.com/watch?v=sKz9QarKa80[/ame]
Rastoff
US Veteran
I wouldn't say that dwell time was an issue. I think Randy felt that a longer dwell time would help the overall accuracy though.
Smakmauz
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from what I've heard, the 40's didn't have that problem. at least not to the extent. I think randy or someone might have explained that he thought it was due to the extra pressure that kept the barrel more stabilized in the initial stages of the blow back. makes sense.
Horn
Member
Finally Hit It Out of The Park
for years. Our sidearms are service grade pistols and are reliable
for defensive shooting__our defense or defense for a citizen in
danger.
Even our military competition shooters back when the 1911 was the issue sidearm used National Match 1911s in competition.
These service grade (The description that got the conversation
out of the park) pistols are designed to be reliable and accurate
to the point and more accurate than most of us.
I think this should end the conversation.
Stay safe out there.
Poli Viejo
Yes, the final point you made explained what LEOs have realizedThe fellow with whom I spoke in one of the armorer recerts mentioned that in the original M&P's the slide & barrel started to unlock when the bullet was typically only up to several inches out of the muzzle, but in the 2.0 the bullet is significantly further. He offered some numbers, but I don't think I wrote them down, as that sort of trivia is unnecessary from an armorer's perspective, albeit sometimes interesting trivia for owners and enthusiasts.
I'd also not be surprised to discover that sometimes a particular set of tolerances might produce some unexpected issues that are better addressed with some different parts, like a new barrel, perhaps. Or some revised specs/tolerances (new twist rate?). Remember reading about S&W replacing barrels now and again when guns were sent back for complaints about horrible accuracy?
Also, remember that delayed unlocking was something the engineers introduced in the metal-framed TSW's, claiming that it also helped reduce felt recoil compared to the standard 3rd gen's.
Lots of folks like to talk about "match-grade accuracy". The M&P, like the Glock and most other standard plastic pistols, was designed as a service-grade gun.
Longer, heavier slides and slightly lighter triggers in some of the "Practical", "Pro series", etc models may make guns easier to run in some competition venues, but it's not like they advertise them to be able to consistently produce groups of less than 2" at 50 meters.
There are probably always going to be compromises involved in deciding whether someone wants a "combat/service" pistol capable of excellent reliability, especially under adverse, extended conditions ... or a comp gun built to tolerances that are much, much tighter, capable of match-grade accuracy, but maybe not able to always run so well in less-than-optimal conditions.
I'll offer that today's engineers and engineering, with CAD and advanced CNC capabilities, are offering us some phenomenal advances over the state-of-the-art for standard/service grade pistols I was owning and using through the 70's and 80's.
for years. Our sidearms are service grade pistols and are reliable
for defensive shooting__our defense or defense for a citizen in
danger.
Even our military competition shooters back when the 1911 was the issue sidearm used National Match 1911s in competition.
These service grade (The description that got the conversation
out of the park) pistols are designed to be reliable and accurate
to the point and more accurate than most of us.
I think this should end the conversation.
Stay safe out there.
Poli Viejo
Smakmauz
Member
- Joined
- Jul 28, 2017
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Well.... I guess the conversation is done now then...
