So I bought an M&P 9mm with a test-round date of December 2013.

From what I've been reading, S&W improved the barrel (and its accuracy) in the beginning of 2013, but mine shows the mark (one dimple, underneath barrel) of being the "older model". What is the easiest method to find out if I have the new & improved barrel or not?

Shoot it. If the accuracy is satisfactory, it really doesn't matter.

Same with mine.....test fired 11/13/13. Appears to have new slide lock, as well as more distinct reset trigger. My barrel also has ONE dot.

It's my understanding that the one dimple is the latest barrel.

Thanks for the information!

It seems that during the rush on guns last year, when Smith ran out of of the "new" parts, they started using the old stock parts to keep production going.


The sear from my understanding was changed from a MIM part to a machined part at one point before this year. My pistol manufactured in May 2014 has a MIM sear.

Not true. I have 2 new barrels. 2 dimples on my 9c and no dimples on the new barrel I purchased to replace my older twist barrel in my fs9. Looking down the barrel you can see the twist is different from the old to the new. The dimples from what had been said, is from the machine that the barrels were made on. Just like the dimples under your slide. What you have stated is what I also thought until I received my new twist fs9 barrel. I thought I received a NOS barrel until I visually checked the barrels.

I just got the L/E MP 9sku 309701 May 2014 build date and its 1 dimple barrel . Has all updates 3 mags and nite sites .

The dimple is a hardness check only.

I doubt that S&W would keep any old stock barrels on hand. They would use them all up and then start installing the newer barrels. Like any business, barrels are money, and they would not leave them setting on a shelf. They would use up all the old barrels and then use the newer barrels. It is possible that some older barrels got put in a wrong location, and possibly were not fully used up, before they started installing the new barrels. This scenario would not be intended by S&W, as the cost for making the new or older barrels would be very similar and there would be no reason for saving the older barrels. Any gun with a warranty issue for a barrel, would get the current barrel.

Back to the OP question, the accuracy between the new and old barrels would be very minimal difference, neither are high grade match type barrels.


Bob

When I visited the S&W factory, the guide explained to us that dimples on slides indicate the machine that produced the part (at the time, they had six large CNC machines in shielded boxes making slides). That way they can detect further down the assembly process which machine is the cause of a problem that might be identified.

I suspect this is the same on the barrels, although I read above that new barrels are all dimpled! (It would be interesting to see if anyone has a barrel with two, three, or four dimples...).

As to the original topic, my M&P9 from around 2011 is fairly accurate but occasionally throws a round high or to the side. (This doesn't happen with any other pistol). I suspect that happens when it is not totally locked up or unlocks too early... So one of these days, I'd like to get a new barrel... I'd really hate to pay for a new one, though, and get some NOS that someone had lying around!

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S&W Rover