Accuracy is coming: Apex M&P Barrels

[agksimon]

I was all set to send my 5" Pro in for a barrel, as soon as I could, until I checked the cost of mandatory overnight shipping, from Michigan to California. The cheapest price is $93 each way. Factoring in the barrel, fitting and testing, it would run me somewhat over $500 to have this done. As bad as I want this barrel, I can't justify the total cost. It's not the fault of Apex, it's the shipping costs. I'm hoping they release the semi-drop-in version quickly.

I've watched several videos on fitting the semi-drop-in barrels and believe that anyone with reasonable analytical and mechanical skills can do the installation properly. If you take a feeler gauge and check the barrel hood front to back and side to side fit and how quickly it unlocks, I can see where an oversized unit filed and stoned to fit, would give better accuracy. The barrel hood on mine has .007 front to rear movement and .006 side to side movement. It also drops down (unlock) quite a bit, after moving the slide back just a few thousandths. I'm reasonably sure I could do a factory fit too, if given the chance.

 

[WR Moore]

Having helped coach several hundred folks through transitional training to the M&P platform, I've got some experience with some of the "inaccuracy".

As Rastoff noted, low left is very common and generally due to poor trigger control (windage of the factory installed sights may actually need adjusted in some cases). However, the M&P doesn't really have a poor trigger, it's just different from the usual crisp short pull of many other semi-automatics. It was intentionally designed as kin to the double action revolver trigger. Some folks have difficulty making the transition and bouncing back and forth from convertional (1911 et all) to M&P trigger does nothing to help.

Yes, there may well be a few M&P9s out there with poor mechanical accuracy due to tolerance stack. A slightly oversize aftermarket barrel might help there. However, during transitional training I noticed that the better shots with our previous TDA sidearm had more trouble adapting to the new pistol than some others. I'll also admit I was one of those.

My personally purchased M&P9 (2006 vintage) is one of only two box stock firearms I own. It flat doesn't need anything, but then I'm not trying to shoot itty-bitty groups at 25 yards/meters. I don't expect it'll impress anyone here, but back in 2006, the LE sales rep noted that the M&P9 was more accurate than the M&P40. That's also been my experience, but my M&P9 experience isn't statistically significant.

 

[ghoffman]

It takes me a while to catch on but I might be getting it now. The "problem" with a semi-auto stems from the fact that the sights are on the slide, not the barrel. This means that the barrel must lock in exactly the same position relative to the slide every time - any change here, even a tiny one - will change the POI while the POA remains dependent on the slide and the sights. So, the gun can only be as accurate as the system that aligns and locks the barrel, even if the sights are exactly on the same point on the target. This tells me that Apex can redesign the barrel to fit tighter and reduce the difference between the barrel position on each shot. Sound right????

 

[Randy Lee]

It takes me a while to catch on but I might be getting it now. The "problem" with a semi-auto stems from the fact that the sights are on the slide, not the barrel. This means that the barrel must lock in exactly the same position relative to the slide every time - any change here, even a tiny one - will change the POI while the POA remains dependent on the slide and the sights. So, the gun can only be as accurate as the system that aligns and locks the barrel, even if the sights are exactly on the same point on the target. This tells me that Apex can redesign the barrel to fit tighter and reduce the difference between the barrel position on each shot. Sound right????

The short answer is yes. The barrel must lock up consistently shot to shot. This is the same for any semi auto pistol. Another critical aspect to accuracy is that the barrel must remain locked up in the same orientation relative to the sights for some period of time after the bullet leaves the barrel. This is what I refer to as dwell time. It is this that the M&P lacks.

The biggest problem that must be addressed is that the way the factory barrel locks up is...simply put- wrong. They might deny it, but the guns would not meet the accuracy criteria for the Army Modular Handgun System trials.

 

[agksimon]

This is an Apex M&P barrel, photo taken from another site.

The photo of the hood and ejection port shows how much excess room there is on my new 5" Pro with the factory barrel. Front to back has .007 of clearance and the loaded chamber indicator area has .006 of clearance. This is why my shot to shot groups are so spread out. When the Apex barrel is fitted, there will be less than .001 clearance, front to back and around .002 clearance where the loaded chamber indicator fits into the slide (per Randy). Also, the barrel lug will be adjusted just enough, so the slide just closes and holds the barrel hood very tight upward into the slide.

 

[Rastoff]

It takes me a while to catch on but I might be getting it now. The "problem" with a semi-auto stems from the fact that the sights are on the slide, not the barrel. This means that the barrel must lock in exactly the same position relative to the slide every time - any change here, even a tiny one - will change the POI while the POA remains dependent on the slide and the sights. So, the gun can only be as accurate as the system that aligns and locks the barrel, even if the sights are exactly on the same point on the target. This tells me that Apex can redesign the barrel to fit tighter and reduce the difference between the barrel position on each shot. Sound right????

Yessir, this is exactly right.

Another critical aspect to accuracy is that the barrel must remain locked up in the same orientation relative to the sights for some period of time after the bullet leaves the barrel. This is what I refer to as dwell time. It is this that the M&P lacks.

Curious. Why would the barrel need to stay locked up after the bullet leaves the barrel? I would agree that it needs to stay locked up until the bullet leaves, but after doesn't make any sense to me. Can you explain the reasoning for this thought?

The biggest problem that must be addressed is that the way the factory barrel locks up is...simply put- wrong.

Wrong? That's fairly strong language. The M&P has the same lock up as the Glock. Is that wrong too? I'm not saying you're wrong in this assessment, just that I haven't heard this before. I'm curious as to why you would say that.

 

[agksimon]

Guns like Smiths and Glocks are set up loose to make them reliable, even if they get a little dirty. This is at the expense of accuracy. Also, if they had to pay someone to hand fit these guns, to get better accuracy, the cost would go through the roof.

 

[Randy Lee]

Yessir, this is exactly right.



Curious. Why would the barrel need to stay locked up after the bullet leaves the barrel? I would agree that it needs to stay locked up until the bullet leaves, but after doesn't make any sense to me. Can you explain the reasoning for this thought?

Wrong? That's fairly strong language. The M&P has the same lock up as the Glock. Is that wrong too? I'm not saying you're wrong in this assessment, just that I haven't heard this before. I'm curious as to why you would say that.

An increase in dwell time attenuates the recoil impulse- in other words absorbs some energy that would otherwise be transmitted to the hand as felt recoil. More importantly, increasing dwell time maintains pre-tension on the barrel so that harmonics within the barrel are kept consistent from shot to shot. Trying to run the dwell time too close to the moment of bullet exit is what got Smith into trouble with accuracy in the first place. This is also why the CZ P-07/P-09, Walther PPQ and Sig P320 will run circles around the M&P in head to head accuracy testing.

Actually, Glock and the M&P system of lockup are very different. The M&P in its current iteration uses the curved surface of the takedown lever that bears against the ramped surface on the underside of the barrel to prevent the slide assembly from sliding off of the frame. It is this ramped surface that lifts the barrel vertically under recoil spring force. Herein lies a big part of the problem.
The engineers at Smith did not account for what is known as the modulus of elasticity (Young's modulus) of the slide. Basically, all steels have the ability to stretch and rebound back to the original dimensions unless it is forced beyond its yield point. In the case of the M&P, the slide stretches in the area of the ejection port as the bullet pulls the barrel forward and the case pushes the breechface to the rear (Newton's Third Law of motion).

Consider that the recoil spring drives the slide forward and the breech face contacts the barrel at the rear face of the barrel hood extension. This is the point of contact that pushes the barrel forward. When the gun is in battery, the barrel being pushed forward by the slide (which is driven forward by the recoil spring) cams upward as the ramped surface of the barrel underlug contacts the takedown lever. When the slide stretches, the upward force on the barrel now becomes variable and is dependent on the pressure of the firing cartridge. Unfortunatley successive shots will never provide identical pressure curves (chronograph will show variations in bullet velocity).
In order to maintain consistent mechanical vertical lock up, the barrel bottom lug must bear against the frame's locking block. There are only two barrels currently on the market that provide this. Bar-Sto is one, and ours.

Glock's slide lock does not apply vertical force against the barrel in this manner.

 

[Bkreutz]

So Randy, when (or are) you planning on a threaded barrel? I don't know if your being located in CA would cause a problem, but it would sure be handy for those of us who use a compensator (or suppressor).

 

[Randy Lee]

So Randy, when (or are) you planning on a threaded barrel? I don't know if your being located in CA would cause a problem, but it would sure be handy for those of us who use a compensator (or suppressor).

We plan on threaded and 40 conversion barrels sometime in the near future. It might have to wait until we move into our new out of CA facility next year.

 

[TAROMAN]

A break for freedom!
Good on ya!

 

[Bkreutz]

We plan on threaded and 40 conversion barrels sometime in the near future. It might have to wait until we move into our new out of CA facility next year.

Where are you moving to? Too bad you have to give up a beautiful spot on the coast.

 

[Rastoff]

Excellent description Randy. Thanks for that.

I'm not convinced that the Glock is completely free of the force you describe. Still, I can see that it is definitely less than the M&P thanks to your description.

 

[Randy Lee]

Where are you moving to? Too bad you have to give up a beautiful spot on the coast.

We will be relocating to Arizona. California has become too inhospitable to not only our industry, but business in general.
We hope to be up and running at the new facility by the summer of next year.

 

[Randy Lee]

Excellent description Randy. Thanks for that.

I'm not convinced that the Glock is completely free of the force you describe. Still, I can see that it is definitely less than the M&P thanks to your description.

You may very well be right. We will use the same design parameters that we used for the M&P to develop an improved Glock barrel too. I am hopeful that we will see the same degree of improvement.

 

[Rastoff]

We will be relocating to Arizona. California has become too inhospitable to not only our industry, but business in general.

I hate to see businesses leave, but you are correct, especially where you are. I'm sure you'll do just as well, if not better, in AZ.

 

[Randy Lee]

I hate to see businesses leave, but you are correct, especially where you are. I'm sure you'll do just as well, if not better, in AZ.

Thank you Rastoff,

I believe it to be the right move for me and for the future of my employees.

 

[S&W Rover]

I've had so-so accuracy with M&P barrels from the factory. Not bad, but generally not up to the accuracy I get with Sigs or with my S&W revolvers. I am an average marksman.

I recall the M&P9 barrel's twist rate was changed about two years ago (rolling change, not announced, but apparently evidenced by the presence of a dimple on the underside of the barrel -- can anyone confirm that?) to enhance accuracy with the 115 grain bullets that supposedly had the most problems. Can anyone say if that has helped things?

My unease with the stock barrel led to my buying a Storm Lake drop-in barrel, which I perceive to be more accurate.

I'm glad to see Randy Lee's technical expertise in this discussion and don't mind if he "promotes" his products while contributing to this forum. I see this sort of thing on other forums too, e.g., Bruce Gray on the SigForum, and as it is being done in true name it is totally ethical. Indeed, it might be considered improper for such contributors to have to make a financial contribution to the forum to be heard! Mr. Lee's research and development of Apex parts has fundamentally improved the M&P platform, making better guns available to all and even driving change by S&W itself as a result. All of us are smart enough to make decisions on whether we buy or don't buy a given product! As for a financial contribution to the forum, that's a good cause, and I, er, think I should send a little something in one of these days myself (soon, I promise!) since I've used the forum classified section to sell a bunch of small items over the years.

My two cents. Comments on the accuracy of Storm Lake, Apex, and other custom barrels would be useful.

 

[agksimon]

I recall the M&P9 barrel's twist rate was changed about two years ago (rolling change, not announced, but apparently evidenced by the presence of a dimple on the underside of the barrel -- can anyone confirm that?) to enhance accuracy with the 115 grain bullets that supposedly had the most problems. Can anyone say if that has helped things?
My unease with the stock barrel led to my buying a Storm Lake drop-in barrel, which I perceive to be more accurate.

My 5" Pro was produced in July 2015 and the barrel has two dimples on it. It has the 1 in 10 twist rate on it and it shoots the same 3.5-5" groups at 25 yards as my Compact, which was made in 2008 and has the 1 in 18.75 twist. You can see the difference in twist rate. I tried a Storm Lake drop in barrel in my Compact and it still shot the same sized groups, so I sent it back. I shot these off a pistol rest and I'm a pretty good shot and have no trouble placing shots into an inch at 25 yards with the right gun. After reading Randy Lee's posts on fitting, I now know how check a barrel to slide fit and feel quite confident in fitting one myself. I have a lighted magnifier, gunsmith files and stones and lots of patience to do it right.
Also, if I ever go to buy another gun, the calipers and feeler gauges are going with me to check fitting, even if I have to try several of the same model, to get the tightest fitting one.

 

[WR Moore]

Actually, Glock and the M&P system of lockup are very different. The M&P in its current iteration uses the curved surface of the takedown lever that bears against the ramped surface on the underside of the barrel to prevent the slide assembly from sliding off of the frame. It is this ramped surface that lifts the barrel vertically under recoil spring force. Herein lies a big part of the problem.

In order to maintain consistent mechanical vertical lock up, the barrel bottom lug must bear against the frame's locking block. There are only two barrels currently on the market that provide this. Bar-Sto is one, and ours is the other

I've got some issues with this explanation. The locking block cam on my M&P9 shows wear patterns from lifting the the barrel. The cam on the bottom of the barrel shows matching wear patterns from engaging the frame block. My barrel hood and slide breech face also show wear patterns that indicate contact as appropriate.

OK, my particular example shoots well. I really can't buy the above explanation as a wholesale explanation of how S&W designed the pistol. No insult intended to Randy. I do accept that a barrel somewhat oversize in relation to factory barrels can reduce slide/barrel play and improve groups though.

IMHO the twist rate change is immaterial to accuracy. Possibly not if you're running heavy bullets at air rifle velocities, but not with industry standard ammunition. S&W used the 1-18.75 twist in their 9mm/.38/.357 guns (and a couple other calibers) for decades without apparent affect upon accuracy. I have a 5906 I shot with Federal 147 gr Hyda-Shoks (~900 fps) and it grouped them in one ragged hole at 25 yards.