Well that was a long read, I dont know if its already been said, and i dont mean to be rude but it may not be the kit, any pics of your hmr groups?
As has been said before use lower mag, at 100yrds I zero at about 6x mag, i use a very cheap Hawke reflex 3-9 x 50 which i brought off ebay for £25, i have broken too many expensive scopes!!.
The home loads could be an issue but they are consistant, when you have a group that opens out like yours it is normally the shooter, it happens to us all, I have good days and bad days, i see your days are mostly bad!, practice dry firing learn your trigger