The small primers, also used by Garrett Ammunition, are to reduce the possibility of one being set off by the edge of the flat on the bullet beneath it in the tubular magazine stack. It won't hurt to use it, but do adjust your loads down for th extra thickness if you want to keep the pressure constant.
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Patron Member