I'd have to agree that your load sounds like the issue. I shoot at the shoulder, not around it, so I have to also say that could help if you need to anchor the deer before it can get lost.

As far as the .44 and 30-30, both will work at 100 yards. 30-30 ballistics, from what I have seen, don't change much in a 14" barrel as opposed to a rifle (and many of those rifles have 16" barrels anyway). So, you're shooting the same 30-30 which has likely taken more deer in the US than any other cartridge. There's no question as to it's efficacy. Deer haven't gotten any bigger or tougher than they were when the 32-20 Win. was taking them cleanly.