.375 prb's out of a .40?

I did a forum search and found a few brief mentions years back, but thought I'd bring it back up. Anybody ever double patched, or maybe used thick denim, etc, to shoot those .375 pistol balls out of a .40 rifle? Results?

For what good reason, would a person want to do so?

FishDFly said:

For what good reason, would a person want to do so?

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1. .375's seem to be readily available; local store stocks 'em by the ton
2. I might want to build a .40, and wondered if .375's would work with light loads for squirrels, rabbits, etc as an option
3. My mind tends to wander off on wild tangents nowadays
4. Just to p!$$ you off, no no just kidding, dont get mad

4. Just to p!$$ you off, no no just kidding, dont get mad

Been reading here since 2004, no shortage of dumb questions.

Yeah, I've been called dumb before, my skin is thick at my age, I just consider the source and laugh it off LOL ... Peace.

No, seriously, .40 intrigues me, and the idea of a light load option sorta lends versatility. As I said, I searched before asking, and there's a precedent:

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This wouldn't be the primary use of the weapon, just maybe every now and then during squirrel season. Was just wondering if others could chime in on it some more.

yellowhammer said:

I did a forum search and found a few brief mentions years back, but thought I'd bring it back up. Anybody ever double patched, or maybe used thick denim, etc, to shoot those .375 pistol balls out of a .40 rifle? Results?

Click to expand...

I’m don’t believe a rifle will know that you are loading it with pistol bullets, so it will load and shoot without complaint, but getting the correct patch combination for accuracy will be the trick. Guessing you will end up somewhere in the .030” to 035” thick range.

Just for reference, I typically use a .600” roundball in my 62 caliber guns with deep radius bottomed rifling. Requires a thick canvas duck patch. The 58s with radius bottom rifling love a 562” roundball in a thick patch.

Try it and see, but once you get a patch thickness that you can get satisfactory accuracy, ditch the double patch idea (one more thing to drop or forget) and find a single thickness patch that measures the same. If you are not successful, folks are making and selling ‘proper size’ roundballs and molds everyday.

@yellowhammer, a 0.380 ball and 0.022 patch would be an easy load in a lubricated patch. I would expect to see considerable gas cutting of the patch unless there was a heavily greased patch and even then, there will be gas cutting. There won't the velocity of a better fitting ball and patch combination. It would shoot reasonably well, but probably not as accurate as the 0.390 ball in the lubricated 0.018 cotton drill patch.

It ultimately depends on what your acceptable results would be and if such a load meets those expectations.

Why not - I don't see the harm in it. It might work out well - try it and let us know.

SDSmlf said:

...folks are making and selling ‘proper size’ roundballs and molds everyday.

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Oh sure, I didn't mean to infer I would only be shooting the undersized balls. Just a light option...

It works just fine with deep grooves and a double patch.

Buy a box and try it
You can’t go wrong. A .390 might work better but might not. A hunting gun might do very well, but not the most accurate at the range.
A squirrel head is about the size of a nine ring, and you can get a forty five scour all day long. You might not get a fifty five x, but you’ll put meat on the table
And you may get fifty five x …. You just never know until you try

I just got my 40 shooting for the first time this morning. I suppose I'll have to try that eventually and see what happens. Can't hurt anything, probably even the target.

I have 3 different 40 cal rifles. All three shoot a .380 ball wrapped in a good thick pillowtick patch lubed with neatsfoot oil very well. They load easy enough to not require a short starter. Ive never tried .375s being I am happy with the .380s. You will not know till you give them a go

I have been using a Hornady.395 ball in mine. Ran out so tried my cast from a lee mold. .395 mold is dropping at .403-.405. Going to try a harder lead