I have been thinking of modifying a .40 4" Shield to a .357 Sig. I was looking for thoughts and ease of conversion. No particular reason just thinking.
Conversion
- Thread starter sotexas
- Start date
STORMINORMAN
Member
Never heard of a 357 SIG barrel for a Shield...? Rechambering a 9mm 
doesn't sound like a particularly good idea to me, and I'm unaware of any 9mm Shield (40 to 9) conversion barrels to begin with...
Converting a M&P 40 Compact is a possibility: please let me know where to find a 357 SIG Compact barrel 1st
! I've been looking for one for a couple years now...
Cheers!
doesn't sound like a particularly good idea to me, and I'm unaware of any 9mm Shield (40 to 9) conversion barrels to begin with...Converting a M&P 40 Compact is a possibility: please let me know where to find a 357 SIG Compact barrel 1st
! I've been looking for one for a couple years now...Cheers!
OP
The 40 compact was my first thought then the 4" Shield popped into my head. Did find this
.40 to .357 Sig M&P Shield Conversion Barrel
.40 to .357 Sig M&P Shield Conversion Barrel
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STORMINORMAN
Member
Thanks for the link! I have honestly never seen that before: I would recommend further research before attempting the use of 357 SIG ammo in any Shield. Their difference in SAAMI pressure is 5K: this is twice more than the 2.5K difference between 40 S&W & 10mm. Note also the barrel is listed as 3.1".
It may be entirely legit & safe: I have no Shields, of either Generation, and don't really feel qualified other than to encourage further investigation.
Be very careful: should you decide to try it, please advise us your experience as I'd believe there are others who may be interested.
Cheers!
P.S. Might consider this being moved to the M&P forum for more exposure...?
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Echo40
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I read an old thread on this very forum on the subject years ago, apparently someone had asked Smith & Wesson about converting an M&P40 Shield to .357 SIG, but the Customer Service Representative advised against it, citing that unlike other variations of the M&P Series, the Shield was never designed to handle .357 SIG, which operates at extremely high chamber pressures which exceed even that of the powerful 10mm Auto cartridge.
That being said, I think that it would be okay so long as you don't intend to put tens of thousands of rounds through your Shield.
Amusingly enough, I was actually looking at .357 SIG Conversion Barrels for the M&P40 Shield earlier today. I'd like to have one, if only for the sake of having the option to shoot .357 SIG in the event of yet another ammo crisis in which more popular rounds become scarce.
If you can find one that's not too expensive, then I say get it.
That being said, I think that it would be okay so long as you don't intend to put tens of thousands of rounds through your Shield.
Amusingly enough, I was actually looking at .357 SIG Conversion Barrels for the M&P40 Shield earlier today. I'd like to have one, if only for the sake of having the option to shoot .357 SIG in the event of yet another ammo crisis in which more popular rounds become scarce.
If you can find one that's not too expensive, then I say get it.
STORMINORMAN
Member
Just follow his link... At under $150 I'd opine it is rea$onable.
Let us know how it works out: I would be very hopeful it would turn out well
especially in the situation you describe. It could certainly be a handful, though...?
Cheers!
Let us know how it works out: I would be very hopeful it would turn out well
PHP:
Cheers!
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OP
I will have my Gunsmith confirm whether or not it is a wise idea and while I can find the 3.1 barrels I haven't located the 4". I was also thinking of the compact (used) to get the extra length, weight, and capacity. Will be going to his shop today.
STORMINORMAN
Member
Re: the 4", if you follow the link, go to barrels, then S&W, and finally 4" you may find what you are looking for...
Cheers!
Cheers!
STORMINORMAN
Member
And one of the 4" conversion barrels is threaded...
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OP
Well I have officially stepped into the darkside. My Gunsmith said just by the Glock 31, add a Timney trigger, and TFX TFO sights and call it good. I did. Will pick it up in about a week. The 4" Shield conversion is still buzzing in my brain.
oworthsr
US Veteran
I have a 4" KKM /40-to-357 Sig conversion barrel for my 4" M&P 2.0 and a 3.5" conversion barrel (can't remember the manufacturer's name) for my 3.5" M&P 2.0. Both shoot fine and use the same .40 cal magazines for the .357 Sig rounds. No other parts were needed to complete the conversions.
