Glad to see the Rainiers worked out in the Kel-tec, although sorry to hear (no pun intended) about the noise involved w. shooting it at a busy indoor range with only plugs. Looks like you're farther down the road to make having fun with that little beast go easier on the budget! Sorry about the thread hijacking in the rest of this...
Where did you get that quote, I didn't see it.
But some do load the .357 pistol bullet in a .35 Remington rifle cartridge. There may be others also, but you can push the .357 bullet out of a .35 Remington or even bigger cartridges like the .358 Winchester or .35 Whelen a lot faster than that bullet can take, especially a cast or plated bullet, let alone a jacketed one..
Hey Cobb, it was way back on the first page of the thread. Just making the point that .380/9mm bullets would be more than a bit "off"
.375 bore size. I've played with .357" stuff in .35 WCF, .350 Rem mag and such with reduced loads (trying to work down to a load for grouse and squirrels with suicidal tendencies that like to come up to within feet of one during big game seasons). Mostly tried 158 gr. cast SWC with a gas check, run through a .358" lubrisizer die, just to try and get it close as possible to fitting the rifle bore, but messed w. some jacketed in there, too. Never had great accuracy results at velocities low enough that I'd trust 'em not to make little critter tatters and finally decided that's the point of Ruger's Bearcat revolver and another reason why there's CB .22 ammo. Besides, I never did figure out how I was going to surreptitously swap out a big game load for a small game fetcher without disturbing a grouse on the other end of the same log I'm sitting on.

I agree that you can run pistol bullets up to lots higher velocities than the bullets are meant for out of rifle cartridges; for that matter, the 200gr bullets meant for .35 Remington can be driven faster than their best performance envelope on game (as in core/jacket separation and otherwise going to pieces instead of advertisement-photo-style controlled expansion) out of the bigger .35s.
Somewhat related, I've
read that the Ruger Blackhawk convertible models with .357 mag and 9mm cylinders don't deliver stellar accuracy from most 9mm ammo simply because of the bullet diameter difference. I could see that and don't think I'd choose to use bullets meant for 9mm in reduced .35 rifle loads if I had .357"-sized stuff available for the same reasoning.