The reason the .357 case is longer than the .38 Special case is to prevent accidentally chambering the .357 in a .38 Special gun. So they should only fit in a .357 Magnum revolver and surprise that shooter with the report and recoil.
I would line all the bullets up and see if the ones in your caliber are all the same shape and length. If so, they should all be within weight spec unless somebody put tungsten, gold, platinum, or depleted uranium into one. It would have to be something more dense than lead, or it wouldn't be able to be heavier and still fit inside. Highly unlikely. I would still call the bullet maker and let him know what happened. You might get some free bullets out of it.
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