Oldshooter: most snakeshot loads will not cycle the action of a semi-auto because the load of shot is not usually heavy enough or shot fast enough to cycle the action. If your 45 acp fires a 230 gn slug at 850-875'/sec, and you are shooting 100 gns of snakeshot at the same velocity, it won't cycle the pistol unless as mcwoodduck sez your pistol is set up to shoot mouse burp loads.
There are a fair number of posts on the 1911/45 site regarding snakeshot loads, or at least there have been. A number of fellas have tried a number of load combos but I wonder if nakeshot is not best fired from a revolver for reliability, as custom loads for a 1911 would have to be brewed up to cycle the action. It takes a lot of shot to get up to 45 acp bullet weight to get a 1911 action to cycle but I think it can be accomplished.
I believe one member has experimented with 40 S&W brass to make jacketed slugs for a 44 magnum, I think, but that is a indication of what can be accomplished with the kind of ingenuity we find here amongst our members. A .410 shot cup may possibly work if it is of the proper diameter to hold shot in a 45 acp but I'm not sure. I believe the shot would need to be contained to give any accuracy from a acp barrel and if we could figger it out we might be able to come up with semi-auto snakeshot.....maybe. I should work on this.....