The best use of cartridge brass for making other projectiles, is as a jacket for swaged bullets.
For handgun projectiles:
-.380 Auto and .223 Rem make great .35 and .38 caliber jackets
-9mm and 9mm Makarov make perfect .40 caliber and decent .41 caliber jackets
-.40 S&W makes great .44 caliber jackets and acceptable .45 caliber jackets
-.45 Auto makes decent .50 caliber jackets
-If you have a supply of fired copper or brass shotgun primers on hand (rare today), they make great .25 caliber jackets
For rifle projectiles:
-.22 (heeled) rimfire makes great .22 through .25 caliber varmint/target jackets
-.22/.17 magnum rimfire make great .24 through .26 caliber varmint/target jackets
-The coming release of .17 WSM will provide a source for good .27 caliber, possibly to .30 caliber, varmint/target jackets
-5.7x28mm FN makes fantastic .30 and .34 (.338) caliber jackets
-.223 Rem makes good .35 caliber, decent .38 caliber, and very tough .30-.34 caliber jackets
-9mm makes extremely tough .30 caliber jackets
-And the list goes on...
Many of those combinations (such as 9mm for .30 caliber jackets) require quite a few dies to draw the case down to the desired size, but some require very little equipment and monetary investment.
Turning 9mm into .40 caliber bullet, for example, can be done in a single operation. CH4D and "BT Sniper" make 'one step' dies that form a lead-core hollow point bullet with a single stroke of the press handle. (Also available for .40 S&W to .44 caliber bullet, or .40 S&W to .45 caliber bullet.)
And, there are some people out there (like myself
) that re-purpose other reloading tools to get the job done "the redneck way".
I swage soft point .44 caliber bullets from .40 S&W cases, using a 7x57mm Mauser sizing die and the bottom punch from a Lee bullet sizer.
You can see/read more here: Something new to play with
I use the bullets in several .44 Mag revolvers, as well as a .444 Marlin rifle.
Performance is equal to any other standard-construction jacketed bullet out there, if not better (the .40 S&W case provides a very tough base).
On page three of that thread
, there are close-up images of one I recovered from the neck of an Elk.
Empty brass = bullet jackets