The only bullet pens I do use the 30 caliber Barnes 140 grain, I do: 30-30, 30.06, 308 and 300 Winchester. I've done a few .243 and .270, but have turned down the 30 caliper bullets for those rather than buy a box of 50 bullets. The full copper bullets are a bit more expensive but you don't have to deal with the lead. Drilling is easy using collets and sharp bits. I typical do a set-up and drill all 50 in a box for Cross or Parker on a Jet 1220VS.