The .45/.410 combo barrels are specifically made over-bore to accommodate the .454 bullet that the .45 colt carries.

Any .410 that is safe to shoot .45 Colt in will be specifically marked ".45/.410".

Do not fire .45 Colt in any .410 not marked for it.

The Brenneke slugs produce more muzzle energy than standard pressure .45 Colt anyway.