Can 32 Auto ammunition be fired in 32 S&W Long chambered revolvers?

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Can 32 Auto ammunition be fired in 32 S&W Long chambered revolvers?

Post by timmy » Mon Nov 30, 2020 2:11 pm

This subject should be approached with a note of caution. Note the dimensions of 32 Auto and 32 S&W Long:

Image Image

The first thing to notice here is that the rim diameter of 32 Auto is smaller than that of 32 S&W Long (and the other rounds based on it, including 32 S&W, 32 H&R Magnum, and 327 Federal Magnum). Whether or not the extractor of a particular revolver is able to grab this rim can only be determined by trying it. Remember that the S&W Long is a true rimmed cartridge, while the 32 Auto is a semi-rimmed cartridge. They are classified this way for a reason. Some Ruger revolvers do shoot rimless cartridges, having extractors that are specially designed for this. However, most revolvers are not so designed, and getting reliable operation is something that may be questionable.

Secondly, note that the 32 Auto cartridge is much shorter than 32 S&W Long, and even shorter than the 32 H&R Magnum and 327 Federal Magnum. If one studies a modern revolver (meaning one made in the 20th Century or later), a ridge in each cylinder chamber can be noted. This is because in the days of modern, inside lubricated bullets, the bullet is smaller than the cartridge case. Referring to the diagrams I've attached, it should be easy to see that the entire bullet may come out of the case of a 32 Auto round chambered in a 32 S&W revolver before the bullet's full diameter encounters and seals this narrower part of the chamber, allowing gasses to exit around the bullet before the full diameter of it enters the narrow part of the revolver chamber (called the throat). This not only allows the escape of expanding gasses, but it also will affect accuracy, as a throated chamber is designed to receive the bullet in the throated section before it has exited the cartridge case. Proper chamber and throat dimensions enables the bullet to enter the throat fully aligned with the throat and subsequent barrel. A bullet entering the throat and barrel crooked will not be accurate.

I might add that Ruger, in those revolvers which do handle both rimmed and rimless cartridges, usually provides a separate cylinder that's properly throated for the shorter rimless round, such as the 45 Colt/45 Auto Blackhawk.

Thirdly, and most importantly note that the 32 Auto operates at a much higher pressure than 32 S&W Long, 20,000 psi versus 15,000 psi. This, in effect, makes 32 Auto the equivalent of a +P load. Is the revolver the 32 Auto is being fired in able to handle this pressure increase? Was it designed to handle this increase? Has it been tested to handle this increased pressure?

Now, there are always those people who offer the argument of, "I've done this for 30 years and never had a problem." Such an argument reminds me of those arguments that go along the line of "My grandpappy smoked cigarettes for 30 years and never got cancer, so i think it's safe for me to smoke."

This is not a very scientific way to approach the matter, is it? Well, people will do what they're going to do, and i know I can't stop them. i also know what I'd do, faced with a similar choice. As my Grandmother used to say, "A word to the wise is sufficient."
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Re: Can 32 Auto ammunition be fired in 32 S&W Long chambered revolvers?

Post by Vikram » Mon Nov 30, 2020 4:00 pm

Excellent article, Tim. Learnt a few things there. Thank you.
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Re: Can 32 Auto ammunition be fired in 32 S&W Long chambered revolvers?

Post by uncle1 » Wed Dec 08, 2021 6:55 pm

hello Timmy, again u have provided a lot of info and I actually can testify some of this info. I have actually done this and can tell u .32 ACP can be fired but it loses its accuracy. Now I would not say it is good for multiple shots as I have no idea about that. in short, can .32acp be fired from a .32 revolver? mine does but at the expense of accuracy so there is no point in firing. And FYI it was an IOF revolver (for the folks from India).

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Re: Can 32 Auto ammunition be fired in 32 S&W Long chambered revolvers?

Post by ckkalyan » Thu Dec 09, 2021 3:21 am

Nice explanation and discussion on the topic timmy!

Reminds me of the huge variation in just 9mm that Ian of Forgotten Weapons that I watched recently.

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Re: Can 32 Auto ammunition be fired in 32 S&W Long chambered revolvers?

Post by timmy » Thu Dec 09, 2021 4:12 am

CK, thanks for posting this! I enjoyed watching it. Ian's videos are always top-notch when it comes to technical accuracy. I don't know how I missed this one, as his youtube link is in my favorites tool bar (Mac user!) and he's always worthwhile to check out.

His 9x21 talk at the end about the legal requirements of civilians not using military cartridges was also interesting.
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Re: Can 32 Auto ammunition be fired in 32 S&W Long chambered revolvers?

Post by ckkalyan » Thu Dec 16, 2021 7:53 am

timmy wrote:
Thu Dec 09, 2021 4:12 am
CK, thanks for posting this! I enjoyed watching it. Ian's videos are always top-notch when it comes to technical accuracy. His 9x21 talk at the end about the legal requirements of civilians not using military cartridges was also interesting.
Besides, Ian is certainly a very passionate young man who also pays much attention to pronunciation, crossing his T's and ... et al. I recall even hickok45 pointing the fact out in his own especially, humorous manner. :D

timmy I liked that last bit too, brilliant circumvention of some ill-thought-out laws, and was wondering what a huge change it could make in the prohibited Indian Scenario. If it could only work! :lol: :mrgreen:
When guns are outlawed, only outlaws will have guns!

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