Actually a crimp groove isn't totally necessary in a cast boolit. I've crimped thousands wherever I need too for them to feed flawlessly in different guns. Marlin 1894 is a good example, haven't found one yet that will feed every 158 or 130 gr bullet (.38 SP)without "double clutching" sometimes with bullets seated at the crimp groove. I have to seat the bullets half ways between the first grease groove & crimp groove ( OAL 1.515 or thereabouts). I have crimped different hardness's from COWW to hard cast commercial stuff between the grooves with no degradation in accuracy. Every match the wife has won in the past 15 yrs was with "between the groove" crimped ammo (rifle & pistol)...woe be my ride home if she ever has to "double clutch" her rifle during a match with ammo I built for her LOL.
No noticeable shortening of the life span of brass that was crimped in the fat part of a bullet, some of mine have been reloaded probably 50 times since 1973 and still usable (and I use a very hard roll crimp).