The question is: "When, and how much to resize?"

When I resize my .45 Colt ammo it rattles around in the cylinder like beans in a set of marachas. Once fired they 'fit' the cylinder.

Would it be OK to simply bell the mouth and then crimp in new bullets (after priming and charging of course). Or, do I now have a case that is so expanded that I will never get an acceptable crimp?

I have read that I should only resize the case 1/2" but I can't seem to be able to adjust my Redding Die for that. I use an RCBS universal decapping die and then tumble all my fired cases so I don't need the sizer for decapping. When I tried to set the sizer for only 1/2" of the case I would have to back the die out so much it would be up inside the turret (T-7) and it didn't seem to do what I wanted anyway.

I load LOTS of 45 Colt ammo.. My loads don't "rattle" but they are easily inserted in my gun. It sounds like you may have a die that seriously sizes the case too much. I once bought a set of dies from the Green company that aparently were 44 mag dies but marked 45 LC. Of course they replaced them at no charge. I also doubt that this happens on a regular basis. It is not inconcievable that your dies simply size the cases TOO much. Do you have access to another set to try. I can adjust my RCBS to sort of neck size without the die being halfway up the press and have often done just that for my accuracy loads. Best of luck with this one....

When I resize my .45 Colt ammo it rattles around in the cylinder like beans in a set of marachas. Once fired they 'fit' the cylinder.
I don't resize my 45 Colt practice loads. Just bell, load and crimp. Watch out that the case doesn't get so large that the bullet slips right into it when seating. I found that out the hard way when I loaded brand new brass without sizing first.

There should be some play between the revolver chambers and the cartridge. This is normal and designed to function that way. Handgun ammo does not have the same accuracy potential as rifle ammo so not much is accomplished by trying to neck size or not size handgun cases. I load for .45 Colt too and I always full length resize the cases. There are times when large flake type powder grains are left unburned in the chambers after firing. Powder grains like Unique are large enough to impede chambering even with full length sized cases. Partially or not sizing handgun cases can lead eventually to difficulties in extraction. IMHO, for those of you who treat handgun cases like benchrest rifle cases, the results are simply not worth the effort.

I've had problems with .45 casings being overworked by resizing when loading high pressure loads for my Bisley. With the hot loads I only resize about 2/5ths of the case length in the carbide sizing die. I usually decap the loads with a universal decapping die when I go this route, but you may simply be able to turn your decapping stem down far enough in the die to make it work.

Before you go load a big batch of shells this way, you should resize maybe 10 cases and make sure all of them will chamber in EVERY cylinder of your revolver. As far as not sizing at all, you're on your own..if the cylinder is oversized enough for the cases to rattle it would likely take a bullet that was quite oversized to have any case pull.

Problem is that you've got 6 individual chambers; not all of them will be identical. IF njust neck sized, will eventually get to the point that each will only fit a specific chamber...makes for a long-long reload.

Better to size just enough that the round will eneter ANY chamber, no real need for any more sizing that that so long and the bullet is a tight fit to the case when seated.