hi all. im new to re-loading. my choosen method of re-sizing cases is to bump the cases back .001 with the full length die. iv started with factory hornady ammo, after firing the ammo, using the hornady headspace gauge iv ended up with 2.1225. all cases are even. (this is 7mm rem mag) so cool, i bumped them back to 2.1215. while setting up the die some cases bumped a bit far, so to make those cases all even and to be kept seperate, i full length sized them down to the shell holder, giving me a measurment of 2.1115 so now i figure, i will just develop two loads at the same time, one with my bumped cases at 2.1215 the other with full length sized cases at 2.1115, no drama. i run my bumped cases through a ladder test going up .5 grains until max. cool now i have a max to not go past, and an idea of velocity. plus a rough idea where a accuracy node maybe. i use the remaining cases to do a few three shot groups to find a good group and a low ES. i also used my few full length sized cases to do some groups. (being that the F/L cases and the bumped cases will give me different results from the different size cases) meanwhile i also full length sized some cases from another barrel, but they gave me another measurment of about 2.1130 which i couldnt really understand. (slightly longer, even though i screwed the die past the shell holder a bit) anyway the bumped cases (most of them) that have been fired or grouped didnt expand properly and seemed to have got slightly shorter with the headspace gauge by maybe .0005 what im trying to do is not full length size but to just bump back .001 but i now have a heap of cases that are a bit short to get my original bump of 2.1215. so i can only really full length size them. but im trying not to work the brass that much. im using 2217 or h1000 the book max is 68.3. and the max i found was 73.5, but at 73 the shot had a wierd sound, so iv called that my max. 73.5 had extractor marks on the case head 73 did not. so i dont really understand why my cases arnt expanding properly, and i have a heap of brass all at different lengths. some are a bit short of my bump to length, very little have expanded to my chamber size and iv ended up with two lots of full length sized cases with different lenghts. (all lengths i speak of are with the hornady head space gauge) how do others keep there cases the same, to in-sure an accurate load. is there anything that sticks out that im doing wrong? even my three shot groups of 71.8, 72, 72.2 didnt expand properly. but the factory superformance ammo had no problem, and it starts at 2.0970 the shortest of all. the one case of 73.5gr that has pressure signs on the case head is the only one that actually grew in headspace length. hopfully, this is understandable, any tips would be great. thanks.