Quote:I have about 150 rounds of once fired hornady but when we tried to reload it we can't get it to size down to chamber in my AR
Unless you have a custom cut chamber like I do in my .204 AR, most standard dies should let your brass function if you have the die adjusted correctly and are bumping the shoulder back sufficiently....I have to bump mine back a little more than normal...
There is always that possibility that your FL die is slightly out of specification and you might consider using a different full length sizing die to see if that alleviates the chambering problem..
Quite a few reloaders advocate using a small base sizing die, but for all of my reloading, I've never found that necessary..It almost always boils down to die adjustment...