I bought a bag of remington brass, for my 300 win mag. I like the federal 210GM primers (Im pretty sure thats what they are ,anyhoo). They fit nice and firm in the winchester brass and nosler brass. do I have a bad batch of brass??
any thoughts

If you are talking about the primers fitting loosely in NEW Remington brass, and you have used your batch of primers in other brass with no problems, yes then you likely got a batch of brass with primer pockets on the large side.

That is not unheard of. You can either try to get the faulty brass replaced (or refunded), or try a different primer. Try a CCI 250 and see how that works, CCI primers are sometimes a tad larger than Federal.

If you are talking about loose primers in fired brass, it probably means your primer pockets expanded. Either because the pockets were on the large side from the beginning, or because you ran your loads too hot.

- mike

P.S. If you are using magnum rifle primers (which would be sensible in a .300 WM), then likely your Federal primers are 215s (as opposed to 210s - a non-magnum primer).

http://www.jamescalhoon.com/primers_and_pressure.php

Something for you re. primer specs. r in s.