I have been shooting the NAP Spitfire Maxx’s for 4 years now. Similar to you, I flies great for me. I have killed many deer and pigs with them. I will very likely have it in my quiver this year for whitetail. Although, there are at least 2 heads (fixed and mechanical) I am interested in trying if I get them to group together, particularly the fixed head.
That being said, I have made 3 shots that made me question the broadhead. Two of those shots were on the same animal, a male wild hog that weighed very close to 300 lbs. if I had to guess. I did not want the hog, but I wanted to deliver a lethal shot as they are extremely invasive and detrimental to the ecology. I shot him in the shoulder and he ran off. About 45 minutes later he return with a noticeable limp in the foreleg. I put another in him in almost the same spot. He ran off again. Neither shot passed completely through. In fact, I saw the 2nd (because of my lighted nock) fall out of him as he ran off, about 30 yards into his getaway. I went to recover the arrow and heard the wounded hog growling in the brush. I backed out until daylight. When I recovered the arrow, the broadhead was closed with flesh stuck in it. I’m imagining that I hit too much shoulder bone, shield, and fat. It was a big mature hog!
Last year I made a poor high, forward shoulder shot on the biggest whitetail I’ve ever seen, probably 250 lbs. I immediately saw low penetration. Again, I saw the arrow fall out of him as he ran off, about 60 yards into his getaway. When I recovered the arrow, it appeared just like the one from the hog, mostly closed blades with meat chunks in it. I had about 8” of penetration. I think I’d hit the thick part of the shoulder blade. I was unsuccessful in recovering the buck. True heartache.
I believe all of these were my fault with shot placement. I really don’t hesitate to use the Spitfires, but I want to get to know a particular fixed head this year before my elk hunt and another mechanical for antelope in 1-2 years.