What Strange parts track sentry kills in MvM

The best place to locate a sentry is where the enemy doesn't know it is. However, that only works once at most if you're lucky and they didn't hear it for some reason.

When strategizing with your sentry placement, remember to rely on yourself and your team to back it up. SGs are phenomenally accurate and can mow down most classes in 1-2 seconds. One of the most effective locations to place sentries is where enemies coming around a corner will be unable to see and hit it before they are well in your team's field of fire. Most people will get caught up on shooting whoever's shooting them, and be an excellent distraction while your sentry's mowing them down.

In your alcove case, I would try to place it against the wall towards the enemy, as if they walk by,

1. their field of view will either
   • not allow them to see it, so they will have to spend a split second aiming at it, all the while being laid into by it, or
   • if they are looking at it, then your team, further down the hall giving you support, will be able to fire at the enemy without challenge
2. the force from the bullets will drive the enemy further into the sentry's field of view, rather than in the "safe" retreating direction, towards the rest of their team

Here it is in ASCII because I'm too lazy to make it in paint.exe

Enemy ->           <- Your team
       ---       ---
         |       |  
         |X      |  
         |       |  
         ---------  

As the occasional soldier, whenever the second point is violated and there is insufficient support being given to the sentry, it's as good as dead because I can peek around the corner and peck it to death (or blow it all up at once as demo).

To answer your title's question, strange flamethrowers only count kills done by that weapon's fire damage. This is either through direct damage (W + M1) or the afterburn. It does NOT count reflects sadly. Taken straight from the TF2 Wiki's strange page:

The following actions do not increase the total kill count:

• Killing an enemy with a compression blast.

Strange - TF2 Wiki

As for kill counts, I have a strange degreaser and flare gun too and my flare gun does have a lot more than the degreaser. My guess is in how I play. I tend to ignite, air blast and follow up with a flare gun shot or the axtinguisher. I reflect a lot also (but those kills don't count). If at range I use the flare gun for ignitions and annoying. Since the afterburn damage on the degreaser is less, then you are less likely to get a kill from that than the other flamethowers. Also if you do the air blast and flare gun, the flare gun's afterburn will override the degreaser's so if you get the kill after that, it's for the flare gun.

I would so love a separate counter on my degreaser for reflect kills, like the sentry kill count on the engy's wrench.