I use the Maglula loader. I shoot a lot of pistol competition which consist of servera stages that require re-charging mags between stages.
Those suckers are a thumb and time saver.
For rifle I have the military stripper clips w/charging guides for the M1A and ARs. They are handy for the same reason as above, only with the stripper clips I can have all the ammo loaded up before the match.
For Bulleye where the most you load is five rounds they are not needed, but if you're gonna charge 18 round magazines for a Beretta they come in handy.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071