View Full Version : Swapping calibers in M&Ps
Being a newbie to M&P's, I must ask: can you (reliably) swap barrels between any of the calibers?
If you have the .357 Sig or the .40 S&W M&P, you can get either:
(1) A conversion barrel in the other caliber (.357 Sig or .40) that you DON'T have
(2) A 9mm conversion barrel. Note that you can convert from .357 Sig or .40 to 9mm, but cannot convert from 9mm up to the others.
There may be other conversion options, but those are the only ones I know of.
The frames are identical between the 9mm, .40 S&W, and 357 SIG guns. So a full size frame will take any of the three top ends, and a compact frame will take any of the three compact top ends.
You can drop a .40 barrel in a 357, or a 357 barrel in a .40 ... but you can't swap anything into a 9mm or put the 9mm in a 40/357.
Between 40 and 357, you will experience about a 2" POI change at 25yd. Most companies simply ignore this. At SIG, they use a different (shorter) front sight on the 357 guns. At Smith, I believe they use the same height sight but actually mill the sight cut lower in the slide. This means that you can change sights without having to do any math or otherwise account for the fact that you've got a 357 instead of a 40.
Thanks. Now for the second part of my question. I should have used a different word than "reliably." Could you/would you feel that an M&P 357 with a 9mm barrel was suitable for duty or concealed carry purposes. "Suitable" and not "Ideal" is the operative word. I would envision carrying it as a 357 assuming my accuracy is acceptable, but would like the option of 9mm if needed. My CFO has me on a short leash and tight budget. :(
Personally, it would take a lot of shooting for me to trust a 9mm conversion barrel in a 40/357 gun in terms of carry or duty suitability. So much testing, in fact, that the cost of ammo would far outweigh the price of a second gun.
Here's my advice: just stick with 9mm.
The frames are identical between the 9mm, .40 S&W, and 357 SIG guns. So a full size frame will take any of the three top ends, and a compact frame will take any of the three compact top ends.
You can drop a .40 barrel in a 357, or a 357 barrel in a .40 ... but you can't swap anything into a 9mm or put the 9mm in a 40/357.
Between 40 and 357, you will experience about a 2" POI change at 25yd. Most companies simply ignore this. At SIG, they use a different (shorter) front sight on the 357 guns. At Smith, I believe they use the same height sight but actually mill the sight cut lower in the slide. This means that you can change sights without having to do any math or otherwise account for the fact that you've got a 357 instead of a 40.
Todd, though not necessarily on topic, I just realized you'd be a guy who might be able to answer this.
I've got a P229 in 357SIG with around 8,000 rds. through it. I got the gun in 1995 so it's a "first-generation" P229 with the frame made in Germany. a couple years ago, I got a .40S&W barrel for it as I thought this would be easier/better/ more reliable to reload than the 357.
It's been near perfect function with factory loads in 357, however it has regular FTE with the .40 barrel so I haven't bothered shooting the .40 much lately.
anyway, I want to start shooting this gun in matches again so my question - do you know of something having to do with different, or possibly wonky extractors in the earlier models or calibers?
I'm hoping that SIG has a quick fix but I wanted to find out if you've got any common knowledge about this problem that I can reference to them before I send it in. TIA
apologies to the OP for the small thread hijack...
Here's my advice: just stick with 9mm.
You're right of course. But I want the 357. It's better. . . . or not . . . but I THINK it is. When I had one I loved everything except, as you point out, the ammo cost. Why don't the ammo makers just cut the price and take a huge loss for a couple years in an attempt to build up market share? Get the gun makers on board because it would potentially boost their sales too? Just hand my a .357 MAG revolver?
p.s. I am completely content with my 9mm, but I want the Holy Grail.
apologies to the OP for the small thread hijack...
NP. I welcome thread hijacks.
Deleted, misunderstood the comment I was replying to.
You're right of course. But I want the 357. It's better. . . . or not . . . but I THINK it is. When I had one I loved everything except, as you point out, the ammo cost. Why don't the ammo makers just cut the price and take a huge loss for a couple years in an attempt to build up market share? Get the gun makers on board because it would potentially boost their sales too? Just hand my a .357 MAG revolver?
p.s. I am completely content with my 9mm, but I want the Holy Grail.
Darrin, as an "early adapter" of, and still a very strong supporter of 357SIG, I realize that my affection for the round is based more on emotional, rather than logical grounds. I prefer it to both the 9MM and .40S&W for a defense caliber.
several folks who know much more than I do on the subject will tell you that the new +P+ loadings of 9MM will do all the 357SIG can possibly do in terminal ballistics. plus, they say, the 9MM has advantages in cost and availability of ammo and in magazine capacity. these are hard arguments to ignore. however, I still love my 357SIG for personal reasons and it will always be my CCW regardless.
for those who believe that velocity is justification in its own right, the SIG will still outshine the 9MM in comparable guns by as much as 100fps. some folks will pooh-pooh that idea. I'll take that advantage for what its worth.
and whether the reliability of feeding a 9mm bullet into a 10MM chamber is a real or mostly hyped advantage, it remains unproven but I'll go with the safe money on this one too. I've never had a failure to feed or fire in about 8,000 rds. of factory ammo so with a sample of only one, I'm obviously in the happy camp.
all the other arguments withstanding, ballistics and capacity don't make up for a poor skill set if you really need it and given the cost of ammo, you'll probably practice and train more with the cheaper stuff. that's where the rubber meets the road.
that's why I have BOTH...
anyway, I want to start shooting this gun in matches again so my question - do you know of something having to do with different, or possibly wonky extractors in the earlier models or calibers?
No, the gun was designed from day one to be as compatible with the barrel swap as possible. I'd be more inclined to think you've got a hinky barrel than a wonky extractor. Do you have access to someone else's P229 40? Ask if he'd let you put 100 rounds through it (installed in your gun, obviously). See if that works. If so, you need to replace your barrel.
You're right of course. But I want the 357. It's better. . . . or not . . . but I THINK it is.
First, I take responsibility because I'm the first one who brought the caliber "debate" into this thread.
Second, if we want to discuss the relative merits of 9mm vs. 40 vs. 357, let's begin a new and separate thread in the ammo & reloading section.
First, I take responsibility because I'm the first one who brought the caliber "debate" into this thread.
Second, if we want to discuss the relative merits of 9mm vs. 40 vs. 357, let's begin a new and separate thread in the ammo & reloading section.
Okay, see the new thread "357SIG REDUX" (from Barrel Swap)
Todd: would you be able to move my post and ra2bach's post to begin it, or should I start it from scratch? Thanks Mister Big Shot.
No, the gun was designed from day one to be as compatible with the barrel swap as possible. I'd be more inclined to think you've got a hinky barrel than a wonky extractor. Do you have access to someone else's P229 40? Ask if he'd let you put 100 rounds through it (installed in your gun, obviously). See if that works. If so, you need to replace your barrel.
gaaaah, I was hoping you wouldn't say that... :(
DD -- Just start a new thread at your leisure.
RT -- Sorry, brother. I could be wrong and I have seen extractor-related issues with other brand 357's (the Stoeger nee Beretta Cougar comes to mind) but not with a SIG-Sauer.
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