There has been some debate about Ackleys claim that the Ackley improved case reduced rearward bolt thrust. Today at the range I believe I experienced what he was talking about. I have a load that I've been using in the 30-30 Ackley. It's not really hot and well below the point of hard extraction, but it is an improvement over the standard 30-30 loads. I found that sometimes the lever would pop open slightly with my handloads. Today I tried a load that was just .2 grians more powder. I got a higher point of impact and no lever popping open. I also shot a string of 5 shots with the lighter load and the lever popped open on almost every one. I measured the brass after and the heavier load was only .0003" larger in diameter than the brass from what was my hunting load. The cases were all sized the same and reloaded in the same session. The only difference was the powder charge. I also tried the increased load with CCI BR 2 and CCI mag primers with the same result. Extraction was very easy and the increased load actually shot a little bit tighter groups. This is now my keeper hunting load. I also measured some brass from a previous range session with a load a full grain less powder but the fired brass was the same dimension as the heavier load from todays session. Those were fired earlier in the summer when the temperature was higher. Today the temp was right at the freezing point. I think this may have contributed to the lever popping open on the lighter loads. The heavier load may have made the brass "CLING" to the chamber and thus reduced bolt thrust as PO. Ackley claimed. I don't know what anyone elses take is on this but it worked for me and from what I have seen I am 100% convinced that this load is perfectly safe in MY rifle. I will also add that on this last range session and the other time when I notice that the lever sprung open a bit, I was using brass that I sized more than I usually do. In the one case I had sized the brass with the shell holder contacting the die. I think that may be part of the reason why the fired case didn't "cling" to the chamber and I experienced the bolt thrust issue.