Random brass

Hey guys I'm brand new to handloading and need some direction. I'm learning to load up rounds for my ruger m77 30 06. While waiting for all of my reloading supplies to come in I prepped a few brass I had saved from my gun. I started reloading them and immediately seen great improvements! Someone gave me a bunch of 06 brass picked up at a range. I'm not having much luck with these. Is this common? Should I only use my fired brass? Will this range brass get better in my rifle after a couple of realoadings? If it will not really shoot good I don't feel like wasting powder and bullets. This stuff is pricey! Thanks .

I'm working up some pretty light loads right now. 55grains of imr4350 . Length is is long as my magazine allows (im still way off the lands) i have it written down, Cci 200 primer ,shooting 2540 fps. The brass all looks good and is rem,win and federal. I just notice that the slightly tight feel when I chamber some of these rounds , these shoot better. Can I increase headspace on some short cases? Fereral seems to be pretty loose. I im full length resizing and don't get very consistant measurements after running them through my lyman resizing die. I guess I will need to order new brass to get the results im looking for... Already a bunch of $$$ spent , what's another $100?What's brands work best for you ? I know the rifle will shoot em straight, I've had some 5 shot groups at 1/2". Trying to master this reloading while funds build up for a scope for my new senero 300 win (still in the box) at the rate I'm spending $ on this reloading venture I'll never get the scope!!