I've been doing the same thing with 1/8" lead wire @ 35 gr/in. I find a 2" hole to be pretty easy and 3" to be my practical limit. GM, what size nail are you using?
Jack, nothing is going to be as tough as ash. Poplar shoots much nicer tho, and with the extra weight up front should shoot even better. I thought about trying 3/16, but that doesn't leave much wood and I find 70 grains ups my total arrow weight and FOC quite nicely. If I want more, I just go to a heavier head.
I killed a 125 lb dressed boar pig a few weeks ago with a Sitka Spruce arrow. It had 1.5" of lead for 50 grains plus a 190 gr VPA Terminator for a total arrow weight of 620 gr and an FOC of 20.6%. Hit it at the last rib and the arrow stopped in the opposite foreleg, pinwheeling the heart on the way thru.