Yes the overall length of the Keith bullets will not allow them to load in the magazine. Not so with the WFN LBT bullets. They can be seated to load in the mag. SUPER accurate in most guns too.
I have used up to 320 grain bullets in 44 carbines, but you can't always get the longer bullets to stabilize in some guns with a slow twist. Also overall length can be a problem in some rifles and not in others. The 280 seems to work in every carbine, so that's why I recommended it
If you wish to stay with jacketed bullets, try the Hornady 265 gr.
It's excellent too.