Re-clock an M&P 340 on my own?

[FivePews]

Hi Y'all!

I've been lurking on the forum for a while. As a former "Tacticool Block Boy", I was quite amazed to find that I was meant to be a J-frame guy. Been doing all my serious shooting/training with J-Frames since Jan 2023.

I settled on the M&P 340 and I have four of them (as well as a pair of 640 Pros for fun). Three of the 340s hit exactly where they should when benched at 15 yards with 148 HBWC. That is to say...they all hit in the same place within an inch or two (behind the dot). These three pistols all hit at the top of the sights with 158 grain .38 RN.

One of them hits 4 inches left and 3 inches high with 148 and is even worse with 158.

So, I sent it back. They "fixed it". As it happens I kept the initial bench target and it is hitting EXACTLY where it was before I sent it in. They said that they replaced the yoke, and etc...no mention of straightening the clocked barrel. The barrel eyeballs the same as it did. Crooked.

This isn't a trigger pull or ammo issue. I benched all four identical pistols with the same lot of reloads on the same day. This puppy is screwy.

I know what you are thinking here. What difference does it make? It's a belly gun. Who cares if it's 4 inches left and 3 inches high at a whopping 15 yards? Well, I do. Part of my weekly training regimen is shooting at a 7 inch circle offhand at 25 yards while on a timer. This pistol can't hit that target unless I remember to give it a very special Kentucky Windage treatment. KW is fine if you only have one pistol, but I'm not gonna do that. For now, it problem 340 been designated as my dry-fire gun. Pretty expensive dry-fire gun IMO.

My question is this, can I clock this barrel correctly on my own? I was a cabinet maker and have some J-frame specific gunsmithing tools. Building jigs and being careful is something I might be able to handle. Scratches and dings on the pistol wouldn't bother me a bit.

I don't mind a pistol that shoots a bit high or low so much, but shooting left or right of POA is just....not OK. Besides, if I could clock it correctly and it still hits high, it might make a great gun for 125-ish grain loads (to hit behind the dot as I expect it should).

Will the barrel shroud turn without ruining the pistol? Is it possible to buy whatever special wrench or nut that it takes to loosen the shroud, then retighten it? I assume this is a special lug that uses the rifling of the barrel sleeve to turn the barrel, but I don't really know how the sleeved barrels work. Is there any hope for this pistol or should I just buy another and hope for the best?

Or, should I sent it back again and wait to find out that they pretended to fix it two months from now?

I need at least four of these pistols and plan to pick up at least one more. You might say I'm committed. You also might say I'm crazy. Two proven pistols for carry, two for the range (I prefer to clean them when I'm in the mood), and one for dry-fire. And, as it turns out, a wise fellow would have one more so that none are missing when one goes off for it's inevitable two-month vacation to S&W. That means six in total. My goal is to have six identical pistols in OEM factory condition that all hit in the same place with the same ammo.

My LGS said that if I order more 340s and pay for them, I can bench them and if POA doesn't equal POI, I can return it for a $100 loss and he'll order the next one to try. We can continue until I win.

Don't get me wrong fellas. I'm sold on the Scandium J-frame life. Great pistols for my needs! Hoping that this is a problem that I can fix on my own. To date, none of these pistols have been modified by me in any way, and all were bought new.

Constructive thoughts would be most welcome.

 

[geeollie]

If you find a great video or work guide or person to direct you in the knowledge of what to do, yes, you can buy the vice and the tools needed.

If you really do not know what you are doing in gunsmithing, this is not a wonderful project to begin with.

 

[WR Moore]

OK, the frame above the yoke is VERY thin. It's easy to over torque the 1 piece barrel and crack the frame, destroying it-even with a steel frame. While they do make tools to use to turn the barrel nut, (it's barrel tube, shroud & nut) it's best not to mess with it-ESPECIALLY with an alloy frame. Allegedly, the factory won't change one piece barrels on an alloy frame. Dunno about the shrouded barrel.

SEND IT BACK!!!!!!!!!!!!!!! Along with a sample target showing just what the problem is. Do mark your point of aim. Also, note that your other 3 examples work just fine.

Re-reading-you could always make that abnormal gun your dryfire gun.

 

[Marshal Tom]

Why take the chance of possibly screwing it up when you have plenty others to get you by.Send it back in and just wait. Personally, since you already own several, I would try one of the 642UC's out. I had an M&P 340 for a long time but I sold it. I now have a 432UC and love it. Much like having your 640 Pro on a diet!

 

[ken158]

You have a gun with a lifetime warranty… but are prepared to buy or make tools, venture into a very critical area with a lightweight frame off youtube video instructions while ordering a couple more guns to range test and take a hundred dollar hit if you don't like where it shoots… but you already own 3 that perform as desired. The manufacturer will eat the shipping both ways and it is their fault if they eat up all their profit in returns… Make them pay until they get it right.

 

[stansdds]

The S&W has a scandium frame, so it's basically a stronger aluminum alloy, but it is still not as strong as carbon or stainless steel. The number one failure of S&W alloy revolver frames is a crack in the cylinder crane recess, directly beneath the barrel. I certainly would not take a chance on messing with the barrel and cracking that frame. Let it be S&W's problem.

 

[Les Greevy]

I would try different grips. I find that on the light weight J frames sometimes different grips change POI. My favorite for the M&P 340 is rubber grip from a Taurus small frame as it covers the backstrap and really on recoil.
Les

 

[Mark IV]

A trend that's annoyed me for years, is this popular compulsion to lather-up a Glock with every ridiculous aftermarket "upgrade" available on the interwebs. Case in point, this poor G26 seen recently on my favorite local classified site........

 

[ken158]

Lifetime warranty, you have others and won’t miss it, - send it back with a target and a note saying fix it, send me another and just keep it but do not return it without repair because it will come back. A call to a supervisor or someone in administration may get some action. We cannot let the lack of QC on their part become an accepted routine.

 

[jack zeller]

Hi Y'all!

I've been lurking on the forum for a while. As a former "Tacticool Block Boy", I was quite amazed to find that I was meant to be a J-frame guy. Been doing all my serious shooting/training with J-Frames since Jan 2023.

I settled on the M&P 340 and I have four of them (as well as a pair of 640 Pros for fun). Three of the 340s hit exactly where they should when benched at 15 yards with 148 HBWC. That is to say...they all hit in the same place within an inch or two (behind the dot). These three pistols all hit at the top of the sights with 158 grain .38 RN.

One of them hits 4 inches left and 3 inches high with 148 and is even worse with 158.

So, I sent it back. They "fixed it". As it happens I kept the initial bench target and it is hitting EXACTLY where it was before I sent it in. They said that they replaced the yoke, and etc...no mention of straightening the clocked barrel. The barrel eyeballs the same as it did. Crooked.

This isn't a trigger pull or ammo issue. I benched all four identical pistols with the same lot of reloads on the same day. This puppy is screwy.

I know what you are thinking here. What difference does it make? It's a belly gun. Who cares if it's 4 inches left and 3 inches high at a whopping 15 yards? Well, I do. Part of my weekly training regimen is shooting at a 7 inch circle offhand at 25 yards while on a timer. This pistol can't hit that target unless I remember to give it a very special Kentucky Windage treatment. KW is fine if you only have one pistol, but I'm not gonna do that. For now, it problem 340 been designated as my dry-fire gun. Pretty expensive dry-fire gun IMO.

My question is this, can I clock this barrel correctly on my own? I was a cabinet maker and have some J-frame specific gunsmithing tools. Building jigs and being careful is something I might be able to handle. Scratches and dings on the pistol wouldn't bother me a bit.

I don't mind a pistol that shoots a bit high or low so much, but shooting left or right of POA is just....not OK. Besides, if I could clock it correctly and it still hits high, it might make a great gun for 125-ish grain loads (to hit behind the dot as I expect it should).

Will the barrel shroud turn without ruining the pistol? Is it possible to buy whatever special wrench or nut that it takes to loosen the shroud, then retighten it? I assume this is a special lug that uses the rifling of the barrel sleeve to turn the barrel, but I don't really know how the sleeved barrels work. Is there any hope for this pistol or should I just buy another and hope for the best?

Or, should I sent it back again and wait to find out that they pretended to fix it two months from now?

I need at least four of these pistols and plan to pick up at least one more. You might say I'm committed. You also might say I'm crazy. Two proven pistols for carry, two for the range (I prefer to clean them when I'm in the mood), and one for dry-fire. And, as it turns out, a wise fellow would have one more so that none are missing when one goes off for it's inevitable two-month vacation to S&W. That means six in total. My goal is to have six identical pistols in OEM factory condition that all hit in the same place with the same ammo.

My LGS said that if I order more 340s and pay for them, I can bench them and if POA doesn't equal POI, I can return it for a $100 loss and he'll order the next one to try. We can continue until I win.

Don't get me wrong fellas. I'm sold on the Scandium J-frame life. Great pistols for my needs! Hoping that this is a problem that I can fix on my own. To date, none of these pistols have been modified by me in any way, and all were bought new.

Constructive thoughts would be most welcome.

Just saw this. I was a Smith amororer and we straitened barrels all the time. It is a simple process, with a lead block underneathe the barrel joint, and a wooden hammer to strike. Any good smith can do this for you,

 

[Lance Boyle]

MGW makes a wrench and inserts if you really think you want to be your own armorer.

I adjusted a M64 that was hitting 14 left at 25 yards. I could not adjust all the way to center because the forcing cone clearance flat for the crane would rotate an edge too far and cause rubbing. So now it’s only 6” off at 25 yards. I tried a few ammo changes but it’s still over there.

I am tempted to have them fix it right.

Anyways I don’t anything but steel or stainless steel. I personally would be too nervous touching a small alloy frame.