Potential issues loading 100 grain FMJs in 9mm

[T_McD]

Looking for potential downsides to using 100 gr. FMJs in 9mm. I have load data so no worries there. They are strictly for plinking, but will be shot out both pistol and carbine.

I am considering getting them to use in .380 but to get a good price break I will get more than I will use in .380, just looking for anyone who has some experience using them in 9mm.

[WebMonkey]

I've shot cast 102gn in my 9mm but that's it.

Worked fine.

Good luck

[tazman]

No downsides that I can see except a possible impact point difference.

[Outpost75]

With typical short-nosed 100-grain FMJ bullets, cartridge OAL will be shorter, about 1.03" and there may be feeding issues. My experience has also been that with the lighter bullets recoil impulse may be inadequate to reliably cycle the gun. Frankly, I don't see the point. Save them for your .380 ACP.

[T_McD]

With typical short-nosed 100-grain FMJ bullets, cartridge OAL will be shorter, about 1.03" and there may be feeding issues. My experience has also been that with the lighter bullets recoil impulse may be inadequate to reliably cycle the gun. Frankly, I don't see the point. Save them for your .380 ACP.

Grrr... I have never had good luck trying to use the same bullet in different calibers. I was just hoping it would work.

[mattw]

Agreed, the recoil impulse may not be large enough with that light a bullet. I have the Lee 105 grain mould and it functions well, but just does not shoot that well. I really think it lacks enough bearing surface to work properly. I have to PC the 105 to get it to work it's best in a 9mm. Now in 38 Special, that is another story. I load them with mild loads by the hundreds for my 2 girls.

[tazman]

Grrr... I have never had good luck trying to use the same bullet in different calibers. I was just hoping it would work.

I wouldn't worry about functioning the pistol. The 115 grain bullets do a great job of that so 100 grain bullets should work well given an appropriate powder charge. Lots of data for that bullet available. Just don't go below starting loads.
There could be a feeding issue depending on the shape of the nose. Most FMJ bullets are either round nose or truncated cone. Both of those should work fine.
I would expect the lighter bullets to shoot a little low and possibly to one side.

[onelight]

Some bullets designed for 380 have a really short ogives so you wind up with a very short overall length that might cause feeing issues in a 9mm just depends on your gun.

[jmorris]

I loaded 10,000 of them, 4,000 were hollow base, the other 6,000 FB (thanks Berry’s for changing your design and doubling my work). They were a lot more work than 147-115 gn bullets but a lot of that was getting a collator to work with the short/fat vs long/skinny bullets, the HB was also an issue with a bullet feeder.

Make sure you have a seat die that won’t let them cock sideways and you’ll be good otherwise.

[RED BEAR]

I see no down side i use 90 gr all the time work great.