357 Sig conversion's

[Stephen Heidelberger]

Has anybody done a 40 S&W to 357 Sig conversion if so what barrel length's are available ?

 

[Neumann]

I bought a barrel and recoil spring to convert a SIG P239 from .40SW to 257SIG years ago. Now I only see kits for the P320 and P229. I wasn't happy with the results, in terms of ballistics and ammunition cost, and never attempted to reload 357 SIG.

If you want .357 Magnum ballistics, look to 10mm. 357 SIG promised but didn't deliver, but 10mm has enjoyed a dramatic recovery in popularity. Consider 10mm to be .40SW on steroids (having once suffered the reverse).

 

[erikpolcrack]

Over the last few years, I've had no trouble converting two semiautos from .40 S&W to .357 Sig. One was a full-sized Glock, the other a Sig P226. I believe the conversion barrels for both guns were from Wolf. As I recall, shorter barrels were available.

 

[cowboy94916]

I have a M&P 40 Smith full size. Its setup for 40, 357 sig and 9mm. I just change barrels and in the case of the 9mm magazines. Works great for all. Only time I ever had an issue was, with range pickup brass, reloads that had some glock 9mm cases in the batch.

 

[M1A4ME]

Bought a factory S&W .357 SIG barrel for my 1.0 M&P .40. Function was fine, accuracy not so great.

Bought an EFK Firedragon .357 SIG barrel for my 4" FNS .40. Accuracy was pretty good.

Bought a TR Enabling .357 SIG barrel for my Shield .40. Accuracy is as good as with the .40 barrel (meaning I'm pretty happy with it.)

I do reload .357 SIG but it's not as simple/easy as 9MM or .40 S&W. Ran into some crimping issues which turned out to be some cases that were longer than others. Never had the issue on straight walled cases. Before I start reloading for .357 SIG again I'll be trimming the cases to the same length. Hate doing that with pistol brass but that might be the fix.

 

[rosewood]

I do reload .357 SIG but it's not as simple/easy as 9MM or .40 S&W. Ran into some crimping issues which turned out to be some cases that were longer than others. Never had the issue on straight walled cases. Before I start reloading for .357 SIG again I'll be trimming the cases to the same length. Hate doing that with pistol brass but that might be the fix.

Get the Lee Factory Crimp Die for the 357sig, it is collet style and case length doesn't matter with it.

Rosewood

 

[swsig]

I converted my 1.0 M&P 40c (3.6" barrel) from 40 S&W to 357 SIG using a Storm Lake barrel. It was a straight drop-in conversion, requiring no gunsmithing and no change to the recoil spring. I have been very pleased with the results. The accuracy at 15 yards for the 357 SIG is equal to that of the 40 S&W, and it is significantly better than the 40 S&W at 20 yards. The 20-yard results are based on 680 rounds of 40 and 650 rounds of 357, so I know the difference in favor of the 357 is meaningful, and not just due to chance. I have had zero malfunctions in the 2900 rounds of 357 SIG I have shot through the Storm Lake barrel.

The only problem now is that Storm Lake is apparently out of business. I've heard good things about KKM barrels, but I have no personal experience with them.

I recommend the conversion. Good Luck and Good Shooting!

 

[oworthsr]

I have the KKM barrels in .357SIG for both my 3.5" Compact 2.0 and my 4" Compact 2.0. Both function flawlessly.

 

[mrshyvley]

It's a shame they stopped making the OEM .357 Sig barrels for the M&P.
Some years back when they were selling police trade in 1.0 40's for a song I bought a couple early ones.
I researched the parts that needed to be upgraded to bring up to later models, ordered 2 OEM .357 Sig barrels and I ended up with two dependable sweet shooting .357Sig/40SW pistols.
I REALLY like the .357 Sig round.
The Underwood 125 grain JHP at 1475fps good hot rounds.

 

[DirtyShirt]

I hate to give up good secrets but go to FreeShippingAmmo.com
They have Federal American Eagle and Speer Lawman 357 SIG FMJ for .50 cents per round and free shipping
They have 357 SIG HST and Gold Dot for .67 cents per round with free shipping

 

[sophie]

I dont know how many years ago, about 15 I think, I bought a S&W M&P 40c Compact to go with a couple of M&P 9mm Compacts I have. I just had to have the M&P 40acp also. At the time Smith and Wesson was selling the .357 Sig barrel to drop in the gun to convert it . I didn’t wait very long before I decided to order the .357 Sig barrel, but it was too long, and the .357 Sig barrel was discontinued. Wouldn’t you just know it.
Well I decided to order the Storm Lake Barrel for the M&P .40c and it’s a drop in and magazines are the same, and I never shot the M&P .40c and the Storm Lake 3.58” barrel is new in the box. Still got them both. Funny how that happens.

 

[CH4]

I have factory 40 and 357 barrels for my P229. Runs flawlessly using the same mags and recoil spring. I like the ballistics of the 357 Sig. I’ve considered getting a G32 or 33.