Accuracy is coming: Apex M&P Barrels

[Randy Lee]

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.

I believe the markings that you see are from different phases of the gun cycling and not the static lockup. When the slide is cycling forwards, the feeding cartridge and then the hood extension force the barrel to move forward. It is the locking block surface that physically lifts the barrel vertically by contacting the angled surface of the barrel cam. The resistive force of the extractor bearing against the case is what holds the barrel low and results in the mating marks that you see on the horizontal surfaces of the locking block and barrel foot.
Also, when the cartridge is being fed into the chamber, the bullet nose contacts the upper surface of the barrel chamber. This lifts the barrel upward, and it is the top of the barrel hood rubbing against the inner surface of the slide that prevents the barrel from pitching too high, which would cause 3 point jams. I know this because the first iteration of Bar-Sto barrels didn't have enough material height and caused the gun to jam nearly every round.
You also have to take into account the rub on the barrel hood as the barrel is unlocking during the firing cycle. The brass still bears against the extractor causing resistance to the barrel as it tries to unlock- so the hood again rubs against the interior surface of the slide only in the opposite direction.

The barrel loses contact with the locking block once the ramped surface of the forward bottom lug contacts the takedown lever. Pulling back even as little as .001" on the slide will change the vertical force on the barrel. I will have a video out in a couple of weeks that demonstrates how unstable the barrel becomes due to the design and execution of the system.

Regarding twist rates, I agree the twist rate should not affect accuracy in an ideal world. But this assumes that the barrel has appropriate pre-tension and dwell time. Most of the factory guns do not have either component.

You are also comparing an all steel, hammer fired pistol to a striker fired, polmer framed pistol. They are entirely two differnt beasts when it comes to firing dynamics.

I will never know exactly why the factory went to a 1:10 twist (I don't think the Engineers want or are allowed to speak to me), but I can make a pretty good guess- torque stabilization of the barrel. It is the reason why the .40 and .45 M&Ps do not suffer from the same accuracy woes.

 

[Jhp147]

Tagged for interest

I'm really getting a great deal of information here, I think we are fortunate to have Randy Lee contribute even if I can't in my non-engineer brain understand the "barrel harmonics when the bullet is gone" part. Randy, as for S&W engineers not being allowed to talk to you, they should be sending you Christmas cards with cash in them. But I would like to hear what they say...never even had a "back channel" chat with one confessing or defending?

 

[uechikid]

What a great thread. Thank you Randy Lee for your interaction and very detailed explanations.

 

[Randy Lee]

I'm really getting a great deal of information here, I think we are fortunate to have Randy Lee contribute even if I can't in my non-engineer brain understand the "barrel harmonics when the bullet is gone" part. Randy, as for S&W engineers not being allowed to talk to you, they should be sending you Christmas cards with cash in them. But I would like to hear what they say...never even had a "back channel" chat with one confessing or defending?

Thanks Jhp,

Think of the barrel like a tuning fork. If the barrel is solidly locked up in the front and rear to the slide and frame, it is what is called pre-tensioned (not sure where the term came from to be honest). In other words, the barrel has some degree of stress like a stretched guitar string. It will move repeatedly in the same manner and small vibrations through the metal can be measured with little change even while the slide and barrel are moved slightly to the rear (dwell time with proper contact between the bottom barrel lug and the locking block).

In the case of the factory barrel, as soon as the slide moves to the rear- even a fraction of an inch, the forces at the front and rear of the barrel have now been greatly reduced. The barrel can now move up, down, left and right with no repeatability.

Try this test- with the gun unloaded and in battery, use your thumb to wiggle the muzzle around and try wiggling the barrel hood around in the ejection port. The barrel is currently pre tensioned- but not in a mechanically repeatable way once the gun fires.

Now, pull the slide back just a fraction of an inch- all it really takes is a thousandth of an inch or two. While the slide is ever so slightly held back, try wiggling the muzzle and chamber area again. You will most likely feel perceptible play at both the front and rear end. The barrel is now unstable in its lock up because of the way it contacts the takedown lever.

The barrel needs to have forces acting on it that are repeatable from shot to shot, and the only way to do that in a semi auto pistol is to make sure that the barrel has those same forces being applied not only while the bullet is moving down the bore, but for some time after.

Hopefully I haven't muddied the water further...

 

[agksimon]

Most of the greatest strides in science came from people who challenged the status-quo. In this case, Randy took on S&W and they won't admit they screwed up. I just wish I had been as knowledgeable about this subject a few months ago, as I am now. I would not have bought my M&P Pro. I'm into it now, so I have to keep going and wait for the Apex barrel to correct the problem.

 

[TAROMAN]

Great explanation.
Likely the excellent accuracy of revolvers with the tensioned 2-pc barrels is due to this same effect.

Looking forward to trying the barrel in my 5" 9 Pro.

 

[uechikid]

@ Randy Lee. When do you anticipate your M&P Barrels to be available?

 

[agksimon]

@ Randy Lee. When do you anticipate your M&P Barrels to be available?

BLACK FRIDAY?

 

[Randy Lee]

We are really trying to get them packaged up and ready to go next week.
It's like Santa's workshop at Apex.

 

[Jhp147]

Thank you, yes, Randy, I re-read some earlier posts and see what you are talking about now. I was only thinking of barrel harmonics like in a rifle, not everything going on at unlocking and relocking affecting consistency.

 

[Randy Lee]

Thank you, yes, Randy, I re-read some earlier posts and see what you are talking about now. I was only thinking of barrel harmonics like in a rifle, not everything going on at unlocking and relocking affecting consistency.

Excellent!

 

[WR Moore]

About the tensioned barrel, that results from the force of the recoil spring exerting pressure high up on the rear of the barrel (hood or sidewalls of the chamber in later 1911s) while the barrel lug is against (pivoting on) the slide stop/takedown lever. This levers the muzzle of the barrel downward, creating a bending tension in the barrel. This exists in most semi-auto pistols.

On other points, you'll see signs of barrel/slide contact in many 1911s where the locking lugs/front of the chamber contact the slide during the firing cycle. It's not exclusive to the M&P series. The use of the slide stop/takedown lever to raise the barrel isn't unknown either, it was a design feature of the S&W metal framed autos. I'm not real sure that's how the M&P works, the wear on the barrel cam argues against it. The wear pattern on my take down lever and barrel seem to show the the only thing the take down lever does is stop forward motion.

This is kind of like arguing about the number of angels dancing on pin heads. If your barrel improves accuracy for those who (think they?) need it without adversely affecting reliablity in less than stellar conditions, do we really care?

1-10" twist was/is pretty standard for 9mm across the pond. It was also the preferred twist for the PPC Open class guns who shot 148 gr wadcutters slowly. So, the change could be sold for either reason even if there was really no practical difference. To the best of my knowledge, the standard .45 twist is stil 1-16".

 

[Heyman]

Thanks Jhp,

Think of the barrel like a tuning fork. If the barrel is solidly locked up in the front and rear to the slide and frame, it is what is called pre-tensioned (not sure where the term came from to be honest). In other words, the barrel has some degree of stress like a stretched guitar string. It will move repeatedly in the same manner and small vibrations through the metal can be measured with little change even while the slide and barrel are moved slightly to the rear (dwell time with proper contact between the bottom barrel lug and the locking block).

In the case of the factory barrel, as soon as the slide moves to the rear- even a fraction of an inch, the forces at the front and rear of the barrel have now been greatly reduced. The barrel can now move up, down, left and right with no repeatability.

Try this test- with the gun unloaded and in battery, use your thumb to wiggle the muzzle around and try wiggling the barrel hood around in the ejection port. The barrel is currently pre tensioned- but not in a mechanically repeatable way once the gun fires.

Now, pull the slide back just a fraction of an inch- all it really takes is a thousandth of an inch or two. While the slide is ever so slightly held back, try wiggling the muzzle and chamber area again. You will most likely feel perceptible play at both the front and rear end. The barrel is now unstable in its lock up because of the way it contacts the takedown lever.

The barrel needs to have forces acting on it that are repeatable from shot to shot, and the only way to do that in a semi auto pistol is to make sure that the barrel has those same forces being applied not only while the bullet is moving down the bore, but for some time after.

Hopefully I haven't muddied the water further...

This is what has finally made my dumbass understand what you are saying. I just tried this and sure enough, you're right. I haven't seen any prices on these barrels. Can you tell us what the cost will be for a 9 pro barrel? And why must we ship it overnight? If we just send the slide, it's technically not a firearm and we should be able to send it any method. Or am I missing something?

 

[Randy Lee]

This is what has finally made my dumbass understand what you are saying. I just tried this and sure enough, you're right. I haven't seen any prices on these barrels. Can you tell us what the cost will be for a 9 pro barrel? And why must we ship it overnight? If we just send the slide, it's technically not a firearm and we should be able to send it any method. Or am I missing something?

If you can follow half of my drivel, you are no dumbass.
Th price on our barrel is $199.95 for both the 4.25" and 5". Both semi-drop in and gunsmith fit.
The gunsmith fit barrels require fitting to both the slide and frame. It is the only way to ensure long term accuracy. Fitting the barrel only to the slide will show degradation of accuracy as slide and barrel hood contact points wear.
This is what some competitive shooters found after they installed aftermarket barrels that had longer barrel hood extensions that required shortening to fit their slides.

I think people will see excellent results with the SDI barrels. I designed the SDI version of our barrel to provide 90% (or better) of the accuracy capability of our gunsmith fit barrel without the expense or delay of sending your gun to a gunsmith. An installation video will be available, and if you have a little patience and a narrow pillar file you should be able to fit the barrel to your gun in less than 30 minutes.

 

[Randy Lee]

The wear pattern on my take down lever and barrel seem to show the the only thing the take down lever does is stop forward motion.

There is a very simple test to confirm whether this is the case. Remove your takedown lever and reinstall the barrel and slide on the frame (Don't install the recoil spring assembly, as it will bind up the gun.).

Push the rear of the slide forward until it is approximately where it would rest in battery.

If your hypothesis is right, there should be no play in the barrel either at the muzzle or the chamber area.

 

[Heyman]

If you can follow half of my drivel, you are no dumbass.
Th price on our barrel is $199.95 for both the 4.25" and 5". Both semi-drop in and gunsmith fit.
The gunsmith fit barrels require fitting to both the slide and frame. It is the only way to ensure long term accuracy. Fitting the barrel only to the slide will show degradation of accuracy as slide and barrel hood contact points wear.
This is what some competitive shooters found after they installed aftermarket barrels that had longer barrel hood extensions that required shortening to fit their slides.

I think people will see excellent results with the SDI barrels. I designed the SDI version of our barrel to provide 90% (or better) of the accuracy capability of our gunsmith fit barrel without the expense or delay of sending your gun to a gunsmith. An installation video will be available, and if you have a little patience and a narrow pillar file you should be able to fit the barrel to your gun in less than 30 minutes.

Thanks randy. Sorry if I missed this but any idea when these will be available?

 

[Randy Lee]

Thanks randy. Sorry if I missed this but any idea when these will be available?

Barrels are going through final inspection and should be through packaging after Thanksgiving. Brownells will be carrying our barrels as well, so the first portion of the run will be ready to go to them as soon as we return from the Thanksgiving break.

My best estimate for release is the first week of December.

 

[agksimon]

Has anyone here checked their M&P barrel fit, to see how much movement they have?
I checked my 5" Pro again today and have .007 front to back and .006 side to side. I removed the recoil spring and takedown lever and put the slide/barrel back in place, where it's supposed to be and could pull it up and down a few thousandths, though I had no way to measure it.
Randy told me that side to side should be .002 or less, front to back .0005 (that's 5/10ths) and vertically off the locking block, no movement at all.
I have my pillar files, honing stones and lighted magnifier, ready to go, as soon as we can order them.
There is no doubt in my mind that a properly fitted barrel will substantially reduce my group sizes with this gun.

 

[lplatta]

APEX barrels... really

I think the APEX kits are fine. Just don't go beyond a carry kit. I went whole hog on an M&P pro for some speed shooting steel race gun. What a piece of ****. You can't time it. Sear release vs striker clearance. Can you imagine a barrel?? Pass. I did buy a Wilson match barrel for my pro and it did improve groups at 25yrds. Then I installed a FSS and flat faced trigger from APEX. Now the once great gun is unreliable. On top of that they would not provide any customer service for me. I would be very cautious of buying a barrel from them.

 

[lplatta]

Remember when you were a start up?

Randy: You and Apex Tactical have done more for M&P owners, than any other ten companies combined. You won't release a product, until it's been thoroughly tested and proven. This means a lot to those of us that frequent this group and I would hope that the moderator(s) would make an allowance for this.
Please don't let one person, posting negative comments, ruin it for the rest of us. We love Apex.

I guess I'm number two. I first bought one of your comp kits a few years ago. Worked great. Later, I went full blown and got the FSS and flat faced trigger. It has caused me nothing but problems. I have had NOTHING but problems with it. I have gone to my standard M&P9 for matches. The PRO is just not reliable with this "razzuu" kit. I'll stick with the stock setup over this one. Don't just sell kits, stand behind them. I have called and emailed on this problem. Got ZERO help. This is from a guy that has installed more than a few of your kits. Go back to when you were a small company and had great CS.