Have heard mentioned several times that best results are obtained .357 SIG by loading .357" diameter bullets not .355" bullets in handloads. What's recommended and the pros and cons? I am talking primarily FMJ's for range use. Thanks.

.357 diameter bullets should be used in .38 SPL, 357 Magnum and .357 SIG. .355 diameter bullets are intended for 9mm.

I find that .356", 38 super bullets work great in my M&P and Glock pistols chambered in 357 sig.

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Dave

The 357 SIG bullet diameter is the same as 9mm, 0.355-0.356". You can use a 0.357" bullet if you wish.

In my Sig P320 in 357 sig , .355 dia. works perfect , very accurate . But in my S&W MP in 357 sig .355 is not the correct size , many flyers . It needs .356 min. I was shooting 124 gr. plated bullets from Ranier .

One of the better reasons for rolling your own is to get the optimum performance out of YOUR specific gun. The only way to find out is to try various components and loads. You might find the best grouping is by using .355 bullets. Or maybe .357 bullets. That's what experimentation is all about.

DWalt, agreed. But just trying to get a head start and avoid any unnecessary variables. Also hoping to buy bullets in bulk. Sounds like it is not worth bulk buying until I sort the diameter out for my gun. Mine is a S&W 4.25" barrel for the M&P Pro CORE.

Thanks to everyone that inputted.

I've had good results with Berrys plated bullets from Dillon. They are sized .356 I believe. I use AA7 powder in my 357 Sig loads, in case you're looking for a powder to start with. These work well in my M&P 357 and several other brands of pistols in the caliber.

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Tom
"Panem et Circenses"

It's still going to be a 9mm barrel. The 357sig takes the cartridge of a 40s&w and necks it down to 9x19 bullet. Which is .355. Now, your gun may like heavier or lighter bullets but their diameter will be the same. A 357mag/38spl bullet will be wider. I would be very very careful about using wider bullets

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FYI, the SAAMI tolerance specification for the .357 SIG bullet diameter is 0.3555-0.003, i.e. .352-.355"

The SAAMI barrel groove diameter tolerance specification is 0.355+0.004, i.e. .355-.359"

The 357sig dimensions in most guns will be for a 9mm/0.355" bullet, BUT, better results with plated & lead will start at 0.356". I have used 0.357" jacketed, just to try them, works fine, but back off your max charges & work up.

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NRA Cert. Inst. IDPA CSO

Speer 4362 .357 Sig bullets: .355 diameter.

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I've still got it made.

Cowboy, I don't know what your velocity was, but Ranier says never over 1200FPS on their bullets. Too soft. Accuracy was awful in my Sig.
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I don't have Alzheimer's- My wife had me tested.