.40-9mm conversion

[Hobbiest]

Have a m&p 1.0 full size in .40 and was going to sell it simply because I dont shoot .40 any more. Just read and trying to confirm that you can put a 9mm frame on the .40 grip. SMITH AND WESSON says no because they dont suggest modifying any gun basically. I cant find any conversion barrels in stock. If the frame does work what do I need besides slide frame, spring, guide rod, barrel and mags? Assuming n that case a 9mm mag will fit? If so and I have 15 round .40 does that mean I need to.17 round 9mm? Ty for any replies. Think I can do it for around 250.00 total and seamed like it would be worth it for that or is it just to outdated? Ive looked at newer 9 mm. I find the 1.0 to be an extremely comfortable grip but my support hand shifts alittle shooting unlike my other guns. Didnt know if this is because its .40 and more recoil or the lack of texture.

 

[M1A4ME]

Do you mean a 9MM slide/barrel on a .40 S&W frame? If so, then yes, they'll fit/work fine as long as you get the right slide/barrel. If your .40 is a full size (15 rounds) then get the 4&1/4" or 5" 9MM slide and barrel and RSA.

Yes, I'd buy some 17 round 9MM magazines.

Are you sure you didn't see any 9MM conversion barrels? I see them pretty regularly. May not be from the same maker but a lot of people want them so they can shoot the cheaper 9MM ammo through their .40 S&W pistol.

M&P Full 40S&W to 9MM 4.25" OAL (works with 1.0 and 2.0) - KKM

Well, it appears, with a quick look, the only one I saw was from KKM. These are really good barrels, but a little more expensive than some others.

 

[serger]

I did my conversions using S&W version 1.0 9mm barrels
and magazines. It was a drop in fit with no machining.

 

[-BTM-]

I’ve done the same thing with CZ and Glock pistols, is there much difference between the 40 & 9mm ejector?

 

[Saudade]

An OEM 9mm barrel will fit and function in a .40 slide (assuming the correct length). The fit at the hood will be a bit looser which may affect accuracy.



A conversion barrel barrel will have the correct hood width.

You should get 9mm mags an perhaps a new recoil spring assembly (at least have a spare).

If this is to become "just another range toy", then an OEM 9mm barrel and mag should do it.

If you intend to use it for home/self defense, you should consider the conversion barrel.

If you want to add an optic, you could look for the 1.0 CORE slides (4.25" or 5") in 9mm. I put a Ported 5" CORE kit on my full size 1.0, then topped with a RMR.

 

[much ado]

40-9 Conversion

Have a M&P40 1.0 with 3.6" barrel. Bought an OEM barrel from Midway and picked up a mag elsewhere. Has never failed to fire or function (and shoots fairly accurately)"but" only ejects the empties about 4 ft while ejecting 40s figuratively to the next county. I do not make a carry pistol of the 9 configuration.

John

 

[erikpolcrack]

Lone Wolf makes .40-to-9mm conversion barrels in which the chamber and bore are ever-so-slightly offset to the left so the .40 ejector gets better purchase on the smaller-diameter 9 mm cartridge base. I know the ones they make for Glocks have this mod and it makes my Glock work just fine with .40 S&W, .357 Sig, and 9mm. In addition to swapping the barrel and the magazine, you probably should also use a weaker recoil spring with the 9mm. The offset chamber and bore don't create any dangerous weakness in the barrel or chamber because the outside barrel diameter and chamber dimensions are .40 S&W size, leaving plenty of metal along the left side.

 

[Hobbiest]

An OEM 9mm barrel will fit and function in a .40 slide (assuming the correct length). The fit at the hood will be a bit looser which may affect accuracy.

View attachment 732393

A conversion barrel barrel will have the correct hood width.

You should get 9mm mags an perhaps a new recoil spring assembly (at least have a spare).

If this is to become "just another range toy", then an OEM 9mm barrel and mag should do it.

If you intend to use it for home/self defense, you should consider the conversion barrel.

If you want to add an optic, you could look for the 1.0 CORE slides (4.25" or 5") in 9mm. I put a Ported 5" CORE kit on my full size 1.0, then topped with a RMR.

I found a Kkm barrel conversion around 200.00. What I was thinking though was I found an original 9mm slide, barrel and recoil rod and spring with 500 rounds on eBay. Starting bid at 175.00 with a day left. Of course it might go for more but thought this would be easiest. Thinking back I now remember how bad the trigger was. I didnt want to spend alot so I polished the trigger bar and bought the plunger from apex and that was it I think and it still has a long reset but its a non gritty , crisp 4.5# break. Not sure if it's the same plunger so I can move mine over and have the same trigger. If I get it for opening bid it felt like my cheapest way to go. If I put to much in it Im getting a new gun.

 

[Hobbiest]

I found a Kkm barrel conversion around 200.00. What I was thinking though was I found an original 9mm slide, barrel and recoil rod and spring with 500 rounds on eBay. Starting bid at 175.00 with a day left. Of course it might go for more but thought this would be easiest. Thinking back I now remember how bad the trigger was. I didnt want to spend alot so I polished the trigger bar and bought the plunger from apex and that was it I think and it still has a long reset but its a non gritty , crisp 4.5# break. Not sure if it's the same plunger so I can move mine over and have the same trigger. If I get it for opening bid it felt like my cheapest way to go. If I put to much in it Im getting a new gun.

I called apex and they confirmed .40 and 9mm plunger are the same so I should have same trigger I believe. Do you know are the mags the same on 1.0 and 2.0? and Am I missing anything?

 

[Hair Trigger]

Have a m&p 1.0 full size in .40 and was going to sell it simply because I dont shoot .40 any more. Just read and trying to confirm that you can put a 9mm frame on the .40 grip. SMITH AND WESSON says no because they dont suggest modifying any gun basically. I cant find any conversion barrels in stock. If the frame does work what do I need besides slide frame, spring, guide rod, barrel and mags? Assuming n that case a 9mm mag will fit? If so and I have 15 round .40 does that mean I need to.17 round 9mm? Ty for any replies. Think I can do it for around 250.00 total and seamed like it would be worth it for that or is it just to outdated? Ive looked at newer 9 mm. I find the 1.0 to be an extremely comfortable grip but my support hand shifts alittle shooting unlike my other guns. Didnt know if this is because its .40 and more recoil or the lack of texture.

Put a .357Sig barrel on it and you don't need anything else. Then you can shoot 9mm bullets all day/night.

For the money and aggravation involved, just sell the .40 and buy a 9mm version. What's the matter with .40 that you don't shoot it any more? It's one of my favorites.

 

[Hobbiest]

Put a .357Sig barrel on it and you don't need anything else. Then you can shoot 9mm bullets all day/night.

For the money and aggravation involved, just sell the .40 and buy a 9mm version. What's the matter with .40 that you don't shoot it any more? It's one of my favorites.

Trying to not have to keep up on many types of ammo. Have four 9mm and and the one .40. ammo is cheaper. less recoil. Just like the 9mm more. Im trying to sell it but not easy around me. At least not at give away prices. I was offered 300.00 for an sig 320 vtac with 3 mags. Anyways I was trying to sell it cause if I do I was going to get a new pistol but not sure I can.

 

[M1A4ME]

The 1.0 and 2.0 models use the same magazines. At least all mine do.

 

[JKP099]

I've had my S&W M&P 357c for 11 years now. It came with three 10 round Mags. One of the first things I did was buy two 15 round Mags and a .40S&W barrel which uses the same mags. A couple of years later I bought a 9mm barrel and magazines. I bought three 12 round Mags and two 17 round Mags for it. I like to think I have the best of three worlds now.
Either brand you get, I would buy the 40S&W or 357SIG version and get a 9mm barrel and Mags for it. I believe the larger caliber guns are built stronger.

 

[Saudade]

The market for .40 is quite soft these days. There are tons on LE trade ins available. 1.0s are going for under $300 (on a few websites).

Unless you have an attachment of some sort to it, I think selling it (even for $250 depending on condition) then add the $250-ish for the conversion barrel and mag will bring you very close to a new 2.0.

 

[STORMINORMAN]

Much like JKP099 I feel the M&P 40s are the most versatile pistols out there: all full size models and my Compact (1.0) run 9mm (conversion) & 357 SIG barrels with zero problems.

Once one insures the right barrel, the corresponding magazine with the correct ammo is on board the fun can begin.

Cheers!

 

[rsrocket1]

I started using a 9mm 4.25" 1.0 barrel with the 9mm mags in my M&P 40 starting around 2008(?). I put over 20k 9mm rounds through it with zero problems. I got a 9mm 1.0 slide from a seller here in 2018 for real cheap and then swapped calibers by just replacing the complete slide. In 2021, I found a dealer who was selling lower frames for $99 so I got a new frame and now have both an M&P40 and M&P 9 1.0,

I have since bought a P320 9&40 and a VP9 and VP40 and have successfully swapped 9mm barrels and magazines into the 40mm guns and they shoot just fine. Same POI through 25 yards which is as good as I can shoot.

I can't say this works with all 9/40 guns but with the M&P 1.0, P320 and VP9/40 I know first hand that it works.

 

[X-Raycer]

I've had an M&P Compact 1.0 in 357SIG since 2010. It wasn't long before I bought a S&W 9mm barrel and mags. So I've been shooting 9mm exclusively since 2012 because of ammo prices. I've not had one problem doing so.
Every so often I'll put 60 rounds of 357 0r .40 S&W through it.

 

[toddstang]

I bought a M&P 40c back when they first hit the shelves. I bought a factory 9mm (Compact) barrel a few years later with a few factory 9mm mags.
I have shot uncounted rounds through this conversion without a hiccup and use it sometimes for CCW.