My largest mistake reloading would have to be confidence before testing. Don't load a bunch of ammo assuming it will be accurate, in fact never assume anything when reloading. Always use caution and follow the books, work your way up, not down from someone on the internet who claimed it was a "safe hot load". If accuracy is the goal, work up a few different loads and go validate their potential on paper before making 100+ rounds. Ask me how I know haha, the bullet puller used to be a good friend of mine. All that being said, your HMR is a GREAT rifle and will really like stuff in the 140gr range, particularly the 143gr ELD-x for a hunting load.