I have been working on a load for my .223. When I got all the stuff to cast I bought some aluminum gas checks. I have tried multiple ways, and even have tried ones from different companies now, but they all seem to get deformed bases when seating/sizing. A member sent me some copper checks to try and I also had another company send me a few gator copper checks to try. Those go on fine and I do not get the base deformation with them. I am guessing the aluminum is just softer.
So my curiosity question is if anyone has found a big difference going from one type of gas check to another as far as loads go. I have not shot any of the copper checks yet. I am hoping that I do not have to go chasing another load down again. My groups with the aluminum were not horrible, but I would get the occasional flier here and there and wondered if it was because of the bases being deformed. It was very hard to cull/separate them by how much the bases got deformed so I just loaded and shot them if they did not look too horrible. But I know that they were not all the same, and who knows if they were all oriented in the case the same way when shooting.
Wanted to see if anyone has tried to squeeze the last bit of accuracy out of their loads and tried switching between aluminum and copper, with all other things being equal. Its probably one of those "just shoot them and see how they do" kind of things, but my curiosity is if the aluminum - being softer - will conform to the bore better than the copper ones. The copper boolits weigh right at 1 grain more than aluminum ones, so I do not think weight will be an issue other than it will have that full 1 grain at the rear of the boolit, not spread out evenly.