380ACP bullet in a .38 SPL case ??

[Dudemeister]

I have about 250 .380ACP 95gr. Jacketed Hollow point bullets (unknown manufacturer) as well as almost 1000 Barnes 100gr hollow base round nose bullets.



I still have a Llama .380 Model IIIA, but I have over 1000 rounds already sitting in boxes, and I doesn't look like I'll be shooting them any time soon, so I'm thinking about loading these bullets in .38SPL cases.

I measured my current Berrys 148gr 38 bullets, and they vary between .356.5" and .357.0". The Berry 100gr. hollow base measure .355" to .356", and the "generic" 95gr. hollow points .355" to .355.5".

I'm pretty sure I can crimp the mouth to get proper retention, but there won't be a heck of lot of bullet inside the case. The ogive on both of these start about .213 from the bottom of the case, so even if I was to seat them to the ogive, there's less than 1/4" of neck contact. Would that be enough?

The other silly thing I was thinking about, is flipping the hollow base around and seating it flush with the case mouth, like a wadcutter. The only concern is the fact that the bottom of the bullet is now a round nose. Will the case split as gases get deflected around the round nose? How is that going to behave as it's making it's way through the barrel? will it cavitate and tumble in flight? IS IT SAFE?

So this is a call to the experienced reloaders, and ballistic gurus. What say you?

 

[Jesse Heywood]

How do the bullets fit your gun? Do they push through the chamber with tension? Usually the 9mm bullets are to small for the chamber and the bore. This leads to gas blow-by and accuracy problems. The hollow base bullets would likely expand to fill the bore.

There could also be a problem with neck tension in the case. This can't be fixed by crimping. I would try loading without the expander.

If you decide to test fire, I would seat the bullet where the case mouth extended just past the ogive and roll crimp, which will keep the bullet in the case. This is also a situation where a case filling powder (Trail Boss) will keep the bullet from going deeper into the case.

I'm not trying to discourage experimentation, but laying out the issues that might rise.

 

[Carl N. Brown]

My experience firing .355" bullets in a Ruger Security Six .357 revolver has been limited.

Limited in part because I was verifying it could done if necessary (bullet shortage) and in part because the resulting accuracy was not impressive.

 

[gotboostvr]

It won't hurt to load up a batch of 10 and give it a go.

Might be a waste of time, but won't hurt nothing.

 

[Walkalong]

If you can get enough neck tension they will work ok.

If you are having a hard time getting proper bullets, or just really want to get them out of your way, I would just save them for the .380 or 9MM (JHPs) down the road.

 

[Archie]

Using the 'undersized' bullets will not damage the revolver, presuming you use 'proper' reloading data for that bullet weight. (Or the next heavier bullet weight.) As mentioned, a .356 inch bullet traveling down a .358 inch bore may result in some mediocre accuracy results. For general practice or plinking, probably 'okay'. The suggestion of not using an expander ball strikes me as a good idea to keep the bullets in the case. May or may not assist accuracy.

On the other hand, revolver barrels (depending on manufacturer) can vary a bit in dimension and the bullets may or may not all be exactly .356". Not to mention the hollow base of the .380 bullet, which MAY expand in the nature of a hollow base wadcutter bullet or Minié ball. (Or may not.)

With reasonable loads, the revolver will NOT blow up. In fact, the recoil may be a bit disappointing.

Yes. I have done this sort of thing. As I recall they were light 9mm bullets (same diameter) in a S&W model 10 or perhaps model 19. Same essential condition.

 

[murf]

size with the 357 magnum/38 spl sizing die, size with the 380 acp sizing die, expand with the 380 acp expander die. the 380 acp dies need only go far enough to hold the bullet. the 357 mag/38 spl die needs to go the whole way.

luck,

murf

 

[rfwobbly]

Accuracy will be "good", but probably never "great".

Also, because there's no cannelure on those bullets to Roll Crimp into, you'd want to get a 38 Spcl Taper Crimp die.

 

[fxvr5]

Neck tension is a possible concern, but if you have enough of it, the bullets will be fine. For my 'undersize' bullets in a 38 Special. I use a Lee undersize sizing die.

Accuracy will depend on the load and not so much on fitting the bullet size to the barrel - at least with jacketed bullets. For example, I have a Ruger Blackhawk 38/357 convertible with a 9mm cylinder. The barrel slugs at .3577". Accuracy of 357, 38 Special and 9mm factory ammo is the same. A handload with 9mm ammo and a .355" jacketed bullet was the most accurate at 24 shots in under 1.5" at 25 yards, with the gun in a Ransom Rest.

Something else to note. 38 Special and 357 Magnum SAAMI specs show a groove diameter of .355" (+.004"), which is exactly the same as 9mm. After slugging lots of barrels I see no obvious difference in groove diameter between 9mm barrels and 38/357 revolver barrels.

 

[BC17A]

With .357" and .358" bullets still available, I'd be saving those others for loading 380 or 9mm.

 

[Dudemeister]

@Jesse Heywood I tried to see how the bullets fit, and the normal one (.357) fits with just a bit of tension through the front of the chamber.. The other 2, the RN hollow base and the jacketed hollow point just drop right through. But they do not fit through the barrel. I measured the barrel groove (bore) and it's about .355" ~.355.5" on 3 of my guns I measured (K38, M686 and Chiappa Rhino). So I'm pretty sure these rounds would seal the bore

@BC17A AS previously mentioned, I already have about 1000 rounds of .380, and it's not one of my "go to" cartridges, so those thousand rounds will probably last me the rest of my shooting life (provided there's no zombie plague). As for 9mm it's one of those rounds that it's just too cheap to bother reloading, so although I do have a die set, I never bothered with it.

@murf With a properly sized .38 case, the bullet can't fit at all, but once I flared the mouth just a bit, I was able to push the bullet in with my thumb all they way, so I'll probably have to use the .380 sizing die if I want to have enough neck tension.

What about seating the round nose hollow base in backwards, all they way in the case like wadcutter? No one commented on that.

 

[Riomouse911]

I think you’re going to get a ton of gas blow-by and the unstable billet will tumble quickly.
No experience doing that, just a semi-educated guess.

Stay safe.

 

[murf]

but once I flared the mouth just a bit, I was able to push the bullet in with my thumb all they way,

use the 380 acp expander die first. your 38 spl expander diameter is too big. the 380 acp should give the right amount of neck tension if that 38spl sizing die squeezes the case down enough. if the 38spl die doesn't reduce the case diameter enough, use the 380 acp sizing die after the 38spl sizer die. then bell the case with the 380 expander die.

you may also be able to get away with using the 380 acp seating die and no crimp. the seating stem should be a good match for your bullets (and will have a taper crimp feature if needed).

luck,

murf

 

[Jesse Heywood]

What about seating the round nose hollow base in backwards, all they way in the case like wadcutter?

The hollow base will expand better with the hollow against the powder. I would try that first.

size with the 357 magnum/38 spl sizing die, size with the 380 acp sizing die, expand with the 380 acp expander die. the 380 acp dies need only go far enough to hold the bullet. the 357 mag/38 spl die needs to go the whole way. murf

Good idea. Why didn't think of that?