Looking at an old 3" S&W yesterday.
The salesman said it was a British lend/lease unit that was chambered for .455 Webley and that it would also fire .45ACP with moon clips. I asked how the ACP headspaced & he told me "with the moon clips."
Huh?
How does this work?
Sometimes, I smile at the complex answers here.
Remember Ockham's razor:
the simplest explanation is usually the correct one.
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"The salesman said it was a British lend/lease unit"
Simplest?
Salesman does not know what he is talking about.
(I know- a completely novel idea)
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"unit that was chambered for .455 Webley and that it would also fire .45ACP with moon clips. I asked how the ACP headspaced & he told me "with the moon clips."
Huh?
How does this work?"
Simplest?
See first answer above.
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"Respectfully, are you sure it was a S&W?"
Simplest?
OP said it was......
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Simplest assumption for this gun?
>S&W 455- 2nd Model (odds are with us for a 2nd, but POSSIBLY a TL, though it seems the "knowledgeable" salesman would have mentioned that

)
>Cyl faced off for ACP with clips
> If a 3", barrel chopped.