You will be pretty safe with a non-pinned 25-5 (post 1980) I have had two, a 6" and my current 4" and both have 0.453 throats and shoot well.

With a pre-1980 25-5 (Pinned Barrel) it's a crapshoot but a lot if not most had oversizewd ( 0.457) throats. Thay can still shoot well if you can size the bullets to the throats.

Ifg the seller can't measure them or have them measured I would be leery. He may already know or maybe he just doesn't know how.

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Sceva
OGCA SWCA NRA