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share projectiles? .357 or .356 9mm/.357 mag


Max It

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Jack, yes. I loaded some .357 mag bullets using .356 projectiles. at the same time i realized that my Blackhawk Convertible comes with two cylinders; one .357 and one .356 (9mm).

I haven't seen any variance in groupings between shooting the two. I used to think the .357's were more accurante out of the Blackhawk however the groups don't show that.

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I recall this topic coming up many years ago in a reloading forum I used to frequent. The consensus amongst the more learned reloaders was that different barrel manufacturers have different bore tolerances.  By that token, if you’ve got a loosely bored 9mm, it may very well shoot .357’s better than .355 or .356.  Conversely, if your 9mm has a tight bore... .357’s may not be the best idea and can result in an over pressure situation.  If it’s really something you want to explore, it would be wise to slug your barrel first to accurately mic your actual bore diameter before experimenting with oversized projectiles.  I’d imagine that going with a slightly undersized projectile (ie, a .355 in a .357 barrel) wouldn’t have much of an effect, at least as far as safety goes. 

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I use 0.356-0.358" lead bullets and 0.356-0.357" jacketed in all my 9x19s. The SAAMI barrel and bullet dimensions for 9x19 and .357 Mag are the same. Also, the larger bullets are often more accurate.

During the last 9mm bullet shortage, it was so easy going on-line and buying .38 bullets...

Edited by noylj
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  • 4 weeks later...

You probably won't notice a difference if using jacketed or plated bullets (I do this with a 38 S&W and .357 bullets). Shoot undersized lead and long term you might see excessive leading due to a poor seal.

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On ‎9‎/‎10‎/‎2018 at 9:56 PM, jkrispies said:

I recall this topic coming up many years ago in a reloading forum I used to frequent. The consensus amongst the more learned reloaders was that different barrel manufacturers have different bore tolerances.  By that token, if you’ve got a loosely bored 9mm, it may very well shoot .357’s better than .355 or .356.  Conversely, if your 9mm has a tight bore... .357’s may not be the best idea and can result in an over pressure situation.  If it’s really something you want to explore, it would be wise to slug your barrel first to accurately mic your actual bore diameter before experimenting with oversized projectiles.  I’d imagine that going with a slightly undersized projectile (ie, a .355 in a .357 barrel) wouldn’t have much of an effect, at least as far as safety goes. 

Makes me smile: years ago, maybe at your recommendation I slugged one or two of my 9mm's and found them to be .3555". I don't remember which ones now. Point is i have several and want to simplify things. I shoot 100 x9mm for every 6 x .38's. so for me to have to stock two different ones and reset the press is a pain. Current supplier of 124 gn Truncated Cone Moly's are .3565". It seems just right both sizes to me, any opinions?

as always

Much obliged,

Max

Edited by Max It
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