You're right, of course. I don't deny that. I just get stubborn, lol.
I have seen more than one drop in sight with my old style Muzzy's. Going to an expandable was driven by a desire for a heavier blood trail, but.... I can't say I haven't found a well-hit deer. I've lost deer, yes...because I made a poor shot.
This past fall, my buck started moving as I released. The result was that the arrow went through his liver only. I didn't even brush against a lung....pure liver hit.
I found him without a blood trail, HOWEVER...I went back the next day (this was right behind my house) and found the blood trail in the daylight. There was GREAT blood from about 10' from where I hit him all the way (~95 yards) to where he laid down. Very good blood...had I been on the right trail, it'd have been super easy to follow even in the dark. I just heard him drop and thrash and didn't need it.
The Muzzy has never given me a "red carpet" blood trial. But if lungs/heart/liver are involved, I haven't had any issues recovering them, either.
On the topic of Spitfires----
My father uses them. I've also taken a few with them. They are a very effective head, however, there is one "gotcha" I've observed with that opening mechanism that the Spitfire employs.
They do NOT open on contact, despite what is said about them. Rage used to have (maybe they still do) high-speed slo-mo footage of a Spitfire going into hide, and what it shows is that the blades open AFTER punching into the hide. I thought "ok, it's Rage, that's marketing."
Then I started looking at every deer my father took with them. Son of a gun if the entry wounds aren't exactly like the footage on the Rage site. Every time. So, you get about a 40-caliber hole on entry.
So, here's where this can become a factor.
Entries are often higher than exits with an arrow, since many bowhunters are in treestands aiming down at their quarry.
If you have a dead perpendicular shot angle, this is pretty well inconsequential, as the lower opening, the exit, is big (blades are fully expanded), and that's the primary source of "leakage". All is good here.
But what happens if you hit the far shoulder or for some other reason have NO exit? Here's where life gets interesting. Or, if the shot is such that the exit is behind the diaphragm (quartering angle), it's effectively the same thing, because once the exit is aft of the diaphragm, blood really doesn't come out that opening much, as the diaphragm acts as a dam of sorts, keeping blood forward of the diaphragm, until it fills enough to spill through the hole the head made in the diaphragm, but at that point, the animal is likely down. And, it'd have to work through the viscera to the exit, which is often clogged with viscera. For whatever reason, my father winds up with that kind of shot angle a lot...hitting lungs, back to liver, exits aft of the diaphragm.
The end result is this-
You don't get a blood trail for a good 20-50 yards, because it doesn't really come out till it works its way out the deer's nose/mouth.
So you have a heck of a time of it finding blood for a long time, and then it comes out in buckets right before you find the animal. But those first 50 yards will be the kind of situation that'll keep you awake at night.
Does the same shot angle yield different results with a different head? I haven't compared apples to apples. But I know I've seen this scenario play out a bunch with his spitfires.
I've also noticed with his crossbow that the Spitfires are not great at shoulder blade penetration. Not that we should be counting on such, but if he hits bone, his bolt isn't penetrating far.
Doesn't mean folks shouldn't get Spitfires. Just go into it "eyes open". Stay off bone and get broadside shots...which is what we should be doing regardless of heads anyway, I guess.