I picked up some Liberty Ammo, Civil Defense 45 ACP 78 gr bullets with a 1900 fps velocity (not kidding). Loaded it in my 325 N Frame Air Lite revolver and the weight was considerably lighter. This is exciting stuff. Watch the gelatin test results. It is devastating. I loaded my carry 1911 magazines and the weight difference is absolutely noticeable. Noticeable enough that I am carrying the 1911 more often too. Shoots about one inch lower at close range than my 230 gr bullets. Recoil is less because you are pushing so little weight. It is worth checking out if you are a big bore shooter that is dealing with knee, back, or arthritic issues and weight reduction is important to you. Lite and powerful. Expensive... but it is carry ammo. About $32 a box of 25! Check out the online gelatin test and and ammo review before you respond to this.

Any need to change springs around (in a semi-auto, of course) when using this ammo? What about barrel twist/wear at those speeds?

No FTF or FTE with the 1911. On the question of barrel wear, I have no idea. Can't shoot enough of it to know. I just use it for carry.

I question Liberty Ammo's conclusions to their testing, but if you are looking for a shallow-penetrating round, have at them.

Yeah, that could be considered the "problem" with the liberty ammo. But like anything else, you have to decide what is best for you.