Using 9mm Bullets for .380 acp reloads?

[MphsTiger1981]

Let me begin by saying I'm a relative newcomer to reloading.

I recently decided to reload some .380s and purchased the necessary dies. I already had some Berry's (.356) 115 grain RN plated bullets on hand for reloading for my 9mm. I found a recipe for this weight bullet in my Lyman's manual, however the first case I loaded has a slight bulge where the bullet is seated into the casing. The OAL is fine, and I loaded at the starting amount of powder. I am just sort of concerned by the bulge in the case. I've noticed some folks selling bullets which are .355 for .380 and some are selling .356 for .380. On first blush, it appears all should work just fine, but I prefer to err on the side of caution.

Did I do something wrong, or does this size bullet require a 9mm expanding die in order to get a good fit for the bullet?

Thanks in advance.

[Guest 6.8 AR]

The trick is if they chamber or not.

[MphsTiger1981]

Thanks.

I put it in the mag, put the magazine in the gun and racked the slide. The round went right in with no trouble, and the slide returned to full battery. Anything else I should look for?

[Jonnin]

I use my 380 bullets in 9 and 357 and 380 all. I have not gone the other way; a 9mm bullet in a 380 is certainly possible but its going to be moving pretty slow and seated a little deep. Due to seating it deep, start with a very weak powder charge and work up, as that increases the pressure pretty fast.

It really depends on which 9mm too. A 380 is 90-100 grains, a 9mm at 115 is only a little more and only a little bigger (but possibly elongated a bit).

If you used a known recipe and it seems to be working, try a few. I do not think you did anything wrong here, but be careful if you try to make your own, always err on the side of wimpy and work up.

Edited April 15, 2012 by Jonnin

[HvBikeWlTravel]

Standard diameter for .380 is .356 for Lead, .355 for copper jacketed. Has to do with hardness.

And 115 gr. is doable, but not ideal. As previously emphasized, work heavy bullet loads gradually.

[Guest Lester Weevils]

Bulges are common for me with Dillon Square Deal B press and dies, on 9mm and .380. They always chamber and shoot fine. I think the bulges are common with other equipment too. I think the size die might bring the case down a little smaller than spec, so when you seat the bullet and it widens the top part of the case back "close to spec" (assuming the bullet is the proper diameter), then the bottom part of the case is still sized a little small, showing the bulge.

That bulge might help the bullet resist setback, because the bullet would have to get whacked hard enough to expand the brass behind it a little bit, before it could set back. If there wasn't a bulge and your slight taper crimp didn't hold the bullet good enough, then the bullet could slide back into the case pretty easy.

Both .380 and 9mm jacketed bullets seem most often 0.355 diameter, and lead bullets seem often 0.356 diameter. There are surely exceptions but that seems common.

I agree with Jonnin a 115 gn bullet in .380 is on the heavy side, but if you follow a good recipe and be careful of powder charge and OAL it ought to work fine.

Edited April 15, 2012 by Lester Weevils