I have the RCBS 270SAA mold, the are advertised to be 270 gr, but are 290 in my alloy, they feed well and work just fine in my Colt .45ACP, I have installed a 24# spring and a buffer, these bullets loaded to around 900fps are very effective hunting loads.
The Handloader magazine had an article with some .45ACP loads utilizing a 300 gr, bullet over 2400. This was about 30 years ago so I do not recall the particulars, folks have put some pretty heavy bullets in the short case and have been doing it for a long time.