I've used it 4 times so far and for some reason I'm able to pull of a ridiculous string of headshots with it to the point I've been accused of hacking on several occasions.

At first I thought it was simply a stroke of luck, I switched back to the Default Sniper Rifle for a day, The Hitman's Heatmaker the next day, The Classic the day after AND back to The Machina and I doubt it was a coincidence because my bodyshot : headshot ratio weren't impressive with the other variants.

The feeling was similar to playing Halo 2 all those years back with all that aim assist (I ain't complaining)
What say you? coincidence or do you also notice you're able to inflict more headshots with the Machina as opposed to the Sinper Rifle variants?

I only ever used the Cuntsman. Can't help ya there friend.

I used to use the machina myself, but I've turned to using the stock almost exclusively. Not being able to hip fire with the machina really puts you at a disadvantage, and the tracer rounds makes you easy to pin point.

That 15% increased damage and target penetration isn't worth it to me since I'm quick enough to get several headshots down range faster than it takes to charge.

I'd say it's just a coincidence you're more accurate with it, you kinda have to be.

I've always found TF2 to be a really difficult game to snipe in

When you get good at sniping TF2 becomes a point and click adventure game.