New barrel required in a .45 ACP pistol
The .400 Corbon can't be shot in a normal .40 caliber gun. It is a necked down .45 case with a .40 caliber bullet. Here is some info from the Corbon website:
Q. Can I use your 400 CorBon ammo in my 40 S&W pistol?
A. No. It is an entirely different cartridge that happens to use the same .400" diameter bullet. Only 45ACP pistols can be converted to 400 CorBon via a new barrel chambered in 400 CorBon.
Q. Just what is the 400 CorBon anyway?
A. The 400 CorBon is a .45ACP necked down to .40 caliber (10 mm). Most any .45ACP can be easily converted to the the 400 CorBon with a simple barrel change. You can use the same magazine, rails and springs. And your gun can be just as easily converted back to the original .45ACP. Performance of the 400 CorBon exceeds the 10mm or 357 Magnum.
Q. Can any .45ACP be converted to 400 CorBon?
A. Just about. 1911A1's of all makes, Glock 21's, SIG 220's, S&W models - M645, M745, M4506, M4516, H&K USP's, Para-Ordnance, Ruger P90 to name the most popular. Don't convert old US Army .45's, they deserve an honored rest.
Q. You mean all I need to convert my 45 to 400 COR-BON is a new barrel chambered in .400?
A. This usually is it for Glock 21, or SIG P220 pistols. The 1911 type .45’s may benefit from an 18-20lb. spring and a few need a 22-24lb. spring. Older 1911’s (series 70 etc.) may need an oversize firing pin to fit their oversize firing pin orifice plus a new firing pin spring. Don’t forget, 1911 guns have been made since the dawn of time by a jillion companies and their specifications vary all over the map. It’s up to you and your gunsmith to set up your 400 pistol properly; COR-BON has no control over it and we are not responsible for it. We manufacture 400 COR-BON cartridges to extremely stringent standards and these cartridges function perfectly in all our factory test guns which include several 1911 pistols, Glock 21’s, SIG 220’s.