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Ammunition incompatiblity in 380 UL

896 Views 6 Replies 6 Participants Last post by  geartow
I noticed right away that the cylinder in the M380 UL has chambers that are too narrow for a large number of bullets on the market, but it literally took me years to take a good picture. Here is what it looks like.

Hold the revolver barrel vertically up, open the cylinder. Take a cartridge, and drop it into the cylinder from the opposite direction (from the front). Do not force! Some brands of ammunition will drop into the cylinder and rest on the mouth of the case. Other brands will only go in partially. These are the brands that make the cylinder jam. The same thing happens when they are inserted from the proper side, so bottoms of the cases stick out and jam the cylinder.

You can see Blazer sticking out in the picture, so a sliver of a bullet is visible.

Needless to say, all those bullets chamber easily in all .380 Auto self-loading pistols, such as Glock 42 and SIG P238.


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Heck, no wonder. Yer loadin' it upside down! Choose ammo carefully, or have the mouths reamed. You should send it back, but.....
Is it just some chambers or all chambers that are under size?
I would say some or all of your chambers are not reamed deep enough.

Bullet should fit a bit snug but if the round is made SAAMI spec it should go fully into the chamber.

All the Best,
D. White
Tight chambers are not good. Probably function fine, but accuracy WILL suffer since the bullet will be swagged below bore diameter of the barrel. Ruger had many Blackhawks in .45 Colt with this malady, but mine's not one of 'em. The cure was to get a smith to bore the cylinders to proper diameter. Now, I bought my .45 Blackhawk used, so someone may have done that already, don't know. But, I've heard to complaint enough to figure sometime in the past, Ruger wasn't sizing chamber throats properly on these revolvers. Ruger's was a habitual production line problem. This Taurus might be a one off, who knows? I'd fix it, though.
I was curious if it was one-off, or if other owners of M380 UL can confirm the same thing.

SAAMI bullet diameter:
38 Special lead - 0.3590 +- .0030
38 Special jacketed - 0.3580 +- .0030
.380 Automatic - 0.3565 +- .0030

Measured diameter
Taurus 380 chambers throats - 0.3550 - 0.3570 or 0.3560 +- 0.0010
bullet Blazer Brass - 0.3550 - 0.3555
bullet Hornady Crit. Def. - 0.3530
bullet WWB - 0.3490
bullet PDX1 - 0.3475

Hornady can be loaded into the revolver with a certain wiggling, the Blazer does not go in. I am somewhat mystified about why a 0.3550 bullet isn't getting into a 0.3560 chamber. My suspicion is that my calibers aren't measuring inside and outside diameters the same.

Surprisingly, all practical bullets are smaller than the SAAMI specification. I don't really think that I'm measuring it wrong, but it's possible.

Now, why is it that all of these feed perfectly in semi-autos? I think that the slide may be slamming them in. In addition, it's possible that the freebore parts of .380 barrels are just a tiny little bit wider than 0.3565 for whatever reason. Don't ask me how the obturation is accomplished, although obviously a bullet deforms when fired.

It may be the case that Taurus simply drilled the chambers according to the theoretical standard (by SAAMI or other standards body). Or, perhaps Brazilan .380 ammunition is always undersized like WWB.
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i have not had any trouble loading any factory 380 in mine . But Tula 9mm will not chamber in my 905 IB.
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