.357 fmj in 9mm?

chris in va · June 28, 2012, 11:34 AM

My LGS only has 100ct bags of 357 125gr. Can they safely be used in a 9mm?

I use 358 LRN but I know those are much softer. My bore slugs at 356.

vladan · June 28, 2012, 11:56 AM

Just few minutes ago yet another post had me pull out my original experiment with .357 bullets in .357sig ( which is really 9mm - .355 diameter bullets)

http://thefiringline.com/forums/showthread.php?t=405689

I do not know how tapered case in 9mm would take the .357 bullets or how tight is your chamber, but I don't thing it would be problem. As always, start with minimum powder charge and work the load up.

chris in va · June 28, 2012, 12:09 PM

I'll just be using these for our matches every two weeks. My plinkers are still homebrew lead 125's.

moxie · June 28, 2012, 12:27 PM

No. You might get away with it if they were cast but not with FMJ. FMJ are typically .001" smaller than bore dia. In your case, which is standard, jacketed should be .355 and cast/swaged .356. So in essence those .357 bullets are .002 too fat.

marklyftogt · June 28, 2012, 12:45 PM

Don't do it unless you want to buy a new gun and/or new hands.

Brian Pfleuger · June 28, 2012, 12:50 PM

It's unlikely to cause any harm if approached correctly. It has been done before (as shown on the above link).

On the other hand, it is obviously far outside standard practice and as such cannot be recommended. It is, at the very least, a practice which should be left to those with considerable experience.

Clark · June 28, 2012, 05:35 PM

I have shot a lot of 158 gr .358" bullets in 9mm.

They are so square on the front, that I have to throat the barrels to get the cartridges to drop in the chamber at 1.169" over all cartridge length.

So it depends on the shape of the bullet.

Adamantium · June 29, 2012, 07:45 AM

I've shot hundreds of .357 jacketed bullets through my 9mm guns, all the way up to max published load with multiple powders and never once saw a sign of over pressure. It is my opinion that the biggest problem you face is the possibility that they aren't going to feed correctly. I've used 110/125 Remington SJHP and 125 Hornady XTP's and only had feeding problems with one gun out of three. Of course I don't blame the gun or the bullet, it's just not a one size fits all kind of thing.

If there is any laboratory pressure testing available comparing .355 bullets to .357 when shot in a 9mm barrel I'd love to see it. It seems like most (possibly all) people I've seen recommend against it are doing it out of their own unwillingness to experiment and not some documented safety problem. Years before I started reloading 45acp I bought a Ruger P90 with a barrel I would later slug at .450. So to me saying that you shouldn't shoot a .357 bullet down a .356 barrel is saying everyone should slug their bore to ensure that factory ammunition is safe to shoot in their gun.

Jim Watson · June 29, 2012, 08:11 AM

C.E. Harris did an American Rifleman article years ago about .38 bullets in 9mm guns. There were no problems in numerous loads. (It was not as simple to get 9mm bullets to run in .38 revolvers.)

The only real requirement is that the loaded rounds chamber freely to avoid what Clark calls "bullet pinch." If the case neck can't expand to release the bullet, that will raise pressure much more than a slightly oversize bullet will.
And it may not even be oversize, there are a lot of 9mm barrels with groove diameters over .355", up to .359" in some cases. Which is why it can be difficult to get .356" cast bullets to shoot well.

mikld · June 29, 2012, 11:22 AM

In my opinion, a jacketed bullet .002" larger in diameter than the groove diameter will have no effect (or very little) on pressure.

June 28, 2012, 11:34 AM	#1
chris in va Senior Member Join Date: December 26, 2004 Location: Louisville KY Posts: 13,806	.357 fmj in 9mm? My LGS only has 100ct bags of 357 125gr. Can they safely be used in a 9mm? I use 358 LRN but I know those are much softer. My bore slugs at 356.

June 28, 2012, 12:27 PM	#4
moxie Senior Member Join Date: October 17, 2006 Location: TX Posts: 513	No. You might get away with it if they were cast but not with FMJ. FMJ are typically .001" smaller than bore dia. In your case, which is standard, jacketed should be .355 and cast/swaged .356. So in essence those .357 bullets are .002 too fat. __________________ If you want to shoot...shoot...don't talk! Tuco USAF Munitions 1969-1992 RVN 1972-1973

June 28, 2012, 05:35 PM	#7
Clark Senior Member Join Date: December 4, 1999 Location: WA, the ever blue state Posts: 4,678	I have shot a lot of 158 gr .358" bullets in 9mm. They are so square on the front, that I have to throat the barrels to get the cartridges to drop in the chamber at 1.169" over all cartridge length. So it depends on the shape of the bullet. __________________ The word 'forum" does not mean "not criticizing books." "Ad hominem fallacy" is not the same as point by point criticism of books. If you bought the book, and believe it all, it may FEEL like an ad hominem attack, but you might strive to accept other points of view may exist. Are we a nation of competing ideas, or a nation of forced conformity of thought?

June 29, 2012, 07:45 AM	#8
Adamantium Senior Member Join Date: June 6, 1999 Location: El Paso, TX Posts: 1,021	I've shot hundreds of .357 jacketed bullets through my 9mm guns, all the way up to max published load with multiple powders and never once saw a sign of over pressure. It is my opinion that the biggest problem you face is the possibility that they aren't going to feed correctly. I've used 110/125 Remington SJHP and 125 Hornady XTP's and only had feeding problems with one gun out of three. Of course I don't blame the gun or the bullet, it's just not a one size fits all kind of thing. If there is any laboratory pressure testing available comparing .355 bullets to .357 when shot in a 9mm barrel I'd love to see it. It seems like most (possibly all) people I've seen recommend against it are doing it out of their own unwillingness to experiment and not some documented safety problem. Years before I started reloading 45acp I bought a Ruger P90 with a barrel I would later slug at .450. So to me saying that you shouldn't shoot a .357 bullet down a .356 barrel is saying everyone should slug their bore to ensure that factory ammunition is safe to shoot in their gun. __________________ New gun, same ol' shot.

June 29, 2012, 11:22 AM	#10
mikld Senior Member Join Date: February 7, 2009 Location: Southern Oregon! Posts: 2,891	In my opinion, a jacketed bullet .002" larger in diameter than the groove diameter will have no effect (or very little) on pressure. __________________ My Anchor is holding fast! I've learned how to stand on my own two knees...

June 28, 2012, 11:56 AM	#2
vladan Senior Member Join Date: March 14, 2010 Location: Central Florida Posts: 813	Just few minutes ago yet another post had me pull out my original experiment with .357 bullets in .357sig ( which is really 9mm - .355 diameter bullets) http://thefiringline.com/forums/showthread.php?t=405689 I do not know how tapered case in 9mm would take the .357 bullets or how tight is your chamber, but I don't thing it would be problem. As always, start with minimum powder charge and work the load up.

June 28, 2012, 12:09 PM	#3
chris in va Senior Member Join Date: December 26, 2004 Location: Louisville KY Posts: 13,806	I'll just be using these for our matches every two weeks. My plinkers are still homebrew lead 125's.

June 28, 2012, 12:45 PM	#5
marklyftogt Senior Member Join Date: March 11, 2012 Location: Salinas, CA Posts: 138	Don't do it unless you want to buy a new gun and/or new hands.

June 28, 2012, 12:50 PM	#6
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	It's unlikely to cause any harm if approached correctly. It has been done before (as shown on the above link). On the other hand, it is obviously far outside standard practice and as such cannot be recommended. It is, at the very least, a practice which should be left to those with considerable experience.

June 29, 2012, 08:11 AM	#9
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,539	C.E. Harris did an American Rifleman article years ago about .38 bullets in 9mm guns. There were no problems in numerous loads. (It was not as simple to get 9mm bullets to run in .38 revolvers.) The only real requirement is that the loaded rounds chamber freely to avoid what Clark calls "bullet pinch." If the case neck can't expand to release the bullet, that will raise pressure much more than a slightly oversize bullet will. And it may not even be oversize, there are a lot of 9mm barrels with groove diameters over .355", up to .359" in some cases. Which is why it can be difficult to get .356" cast bullets to shoot well.