M&P Full Size - .40 to 9 Conversion

[semperFi]

I read quite a bit in the forums about "Conversion Barrels" and the stars aligned recently with Quantico Tactical offering the M&P FS for $400 before the S&W military rebate; A storm lake Conversion barrel that was in stock (Cheaper than Dirt), and some 9mm Mags at a decent price.

I gave it a good cleaning, fired 150 rounds of .40 to break the weapon in on federals; cleaned it again, and switched barrels; and shot 150 rounds of federal 9mm but I mixed some 124 grain rounds in there vice all 115s - no issues whatsoever (clearly to be expected as noted in way to many forums to disbelieve).

Another tip-off is the way these barrels only last a short while till their sold out again.

I guess I'll have to round out the pkg with a .357 sig barrel if I ever find one - preferably a plain Jane one.

This all said and done - other than the versatility of the weapon, I'm not really sure one can use the "cost-savings" feature to justify the expense on 9mm vice .40 ammo as the cost differential is around $5 to $9 a box or 1 to 2K rounds of ammo spent on conversion vice just plain shooting.

Other than that - Its pretty neat to be able to do it and sometime get to experience a .357sig with only the purchase price of a barrel and cost of the ammo.

A real nice weapon; I guess a natural progression from the M&P22 and 9mm Shield. Thanks to the massive forum coverage of the issue as well as alerting me to Quantico Tactical and their LE/Military sales programs as well as other nuggets of invaluable info.

 

[bikendan]

i also bought my M&P 40FS from QT, for the $398 price.
after searching and searching for a conversion barrel, happened to find a Storm Lake one at a LGS.
they also had a couple of 9mm mags.

so, i've had all this since Jan., 2013 and have not had any issues with shooting 9mm.

i do agree that around here, 9mm isn't that much cheaper than 40 cal, only 4-5 cents a round cheaper.

 

[Double-O-Dave]

Semper Fi:

Good luck finding a .357 Sig barrel - I've been looking for one for my 40c for a couple of years now without any success. .357 Sig is an interesting round, very loud, but I like having some diversity in my collection.

Regards,

Dave

 

[DASA]

i do agree that around here, 9mm isn't that much cheaper than 40 cal, only 4-5 cents a round cheaper.

Ouch. Once again you poor folks in CA get to pay the beautiful weather tax. I buy 9mm at least 10-12 cents a round less than .40 S&W.

.40 S&W is only 4-5 cents per round cheaper than .45 auto.

Standard internet/Good Gunshop-Walmart target ammo prices:

9mm $12.95-$14.95 per 50
.40 $16.95-$18.95 per 50
.45 $17.95-$21.95 per 50

If I was buying a new M&P it would be a 9mm. I picked up a used M&P 40 FS because it was a screaming deal ($300).
As soon as I find a new factory 9mm barrel under $100 the M&P 40 will become a 9mm.

Stay Safe.

 

[mustangman]

I'm in the 40 camp already, so I'm thinking about the added versatility of the FS as well. Even though I may never convert to 9mm, its nice to have that option without having to buy a whole new gun. The only way I would do it though is with an actual conversion barrel that's made to fit the 40 slide. Dropping a factory 9 in that doesn't have the tight fit is not something I would risk.

m&p 357 sig barrel | eBay

 

[semperFi]

I'm in the 40 camp already, so I'm thinking about the added versatility of the FS as well. Even though I may never convert to 9mm, its nice to have that option without having to buy a whole new gun. The only way I would do it though is with an actual conversion barrel that's made to fit the 40 slide. Dropping a factory 9 in that doesn't have the tight fit is not something I would risk.
E
m&p 357 sig barrel | eBay

I guess you show there are some out there! I went with a storm lake conversion

 

[mustangman]

I guess you show there are some out there! I went with a storm lake conversion

Sorry I didn't elaborate on the link, I was in a hurry, and just threw it in at the end. Ran across it and thought I'd put it out there if anyone was interested.

 

[semperFi]

KIT/BARREL ORGANIZATION HINTS

Just wondering on how everyone with multiple barrels/mags keeps all their stuff. I've seen a few posts where people have mixed up their ammo/mags in the wrong barrel and I suspect that this is a concern at S&W in formally recognizing the practice and maybe offering their own "Superkit."

 

[bikendan]

in my range bag, i keep the 40 mags on one side and the 9mm mags on the other. i also keep the SL conversion barrel right next to the 9mm mags.

haven't mixed them up yet and don't intend to. i don't put both ammo types out at the same time. i pull out one caliber at a time. i shoot one caliber then put the ammo and barrel and mags away, before shooting the other caliber.

 

[NJM15]

I converted my M&P 40 to 357 Sig using a KKM barrel using the same 40 cal. magazine, with good results. Only problem is finding ammo for it and paying a higher price compared to the more popular calibers.
Average price for them is 30 to 35 dollars, now I reload the 100 rounds I bought, I have never seen any 357 Sig brass in the bucket at the range.

 

[NJM15]

Semper Fi:

Good luck finding a .357 Sig barrel - I've been looking for one for my 40c for a couple of years now without any success. .357 Sig is an interesting round, very loud, but I like having some diversity in my collection.

Regards,

Dave

I bought a barrel directly from KKM a alittle high 175.00 but readily available

 

[DocSunShine]

Congrats, as you've found out the M&P 40s are very versatile and you could legit run it as a 9mm exclusively and expect utter reliability!

 

[semperFi]

in my range bag, i keep the 40 mags on one side and the 9mm mags on the other. i also keep the SL conversion barrel right next to the 9mm mags.

haven't mixed them up yet and don't intend to. i don't put both ammo types out at the same time. i pull out one caliber at a time. i shoot one caliber then put the ammo and barrel and mags away, before shooting the other caliber.

EXCELLENT! I figured this would be the only way to keep things in control. I plan on most likely taking one set-up to the Range at a time with accompanying ammo etc.

I look forward to finding a .357sig barrell and getting to test the round, though I wish i had a setup like hickock45's vice an indoor range.

 

[Johnmuratore]

I've got a .40c with a KKM .40 to 9mm conversion barrel.
I keep the barrel together with the mags for each caliber separate and only have one caliber of ammo out of the safe at a time. It makes me think and double and triple check what I'm doing before I leave for the range, which isn't a bad thing.

It's really neat to be able to shoot both out of the same gun and the difference in cost here in Mass is about $5/50 rds.

 

[DanKatl]

I have a Storm Lake 9mm conversion and a factory 357 Sig. I picked up orange base plates for my 9mm mags to make them stand out. And I never put put more than one caliber at a time.

 

[rdtompki]

The last time I cleaned my 40 and my wife's 9mm side-by-side I put my 40 barrel into my wife's 9mm slide. Surprise, I couldn't get the slide on the frame. Won't do that again.

I'm getting a second M&P 40 and will definitely get a conversion barrel so I don't have to "borrow" my wife's 9mm. I use model airplane paint on the bottom of the mags to differentiate the 9mm and 40 cal mags BTW.

 

[Bandy. From the FILES]

Ok. How about putting the .40 slide,barrel, and mag(s) on the 9 frame?
I would think one can not do this due to size differences.
I'd love to be able to do it. Finding mags for the 9 is.....well damn near impossible and when I do their $45+. Yeah not gonna happen.

 

[rsrocket1]

Ok. How about putting the .40 slide,barrel, and mag(s) on the 9 frame?

Brandy, that does work. The frames are identical. You could also heat and bend the lips of a 40 mag and use a 9 follower (there were instructions on one of these forums somewhere).

Once in a while you can actually find someone selling the complete slide assembly pretty cheaply.

 

[Bandy. From the FILES]

Nice.
Now do I HAVE to swap followers?

 

[rsrocket1]

You might not even have to modify the mags. Try loading some 9mm rounds in your 40 mag. Some people have had success, some say the last round does not feed. You'll never know unless you try it.

If you need to change an M&P40 mag into a 9mm mag, here are the instructions.