Is it truth or is it crap

[Catfish]

Many, many years back they used to sell single shot .410`s that were marked .410 shotgun or .45 colt. If I rember correctly they stopped in the 1920`s. My guess is that they had a little larger bore than .410. I would not recomand shooting a .45 colt in any .410 shotgun. Max. presures on the shotgun in abt. 15,000. I believe moderen .45 colt ammo is loaded to 35,000 psi. and it the bore is really .410 the presure would be considerably higher.