I bought an xp 100 in 221 fireball to use as my fall Turkey gun. Can anyone give me some help with bullet selection. I want to eat the Turkey too. Lol!

Good luck with that. I used a .223 Contender a while on turkeys with 40 & 50 gr. BTs. Got some, lost some. Also lost some with .357, .44, & .45-70. Finally settled on .454 Casull!! with 260 gr. Speer Mag HP bullets. I'm up to 36 straight one shot kills.
The key to killing a turkey with a handgun is an instant killing shot. For me it's a broadside shot high in the wing butt. There's no meat loss with this. Even this shot did not work in the above calibers. I hit them all. They flew/ran away and usually not recovered. Loosing a turkey to a 500 gr. .45-70 bullet is a definite reality check. That's when I switched to the .454. Haven't lost one since.
Sure, you'll get a lot of answers here about different calibers/bullets. Sure, all of them will work sometimes, but to be consistently successful you need placement/speed/caliber.
I think for your Fireball to work reliably a 40 gr. BT would be the way to go. You'll need all the velocity help you can get with that small case.

One with the 454 and two with the 41....

6 with 44mag and 240jhp, and 1 with 9mm and 115jhp

Some body shots and some with low neck, high wing butt shots

Here in Texas we can hunt Turkey with rifles, I?ve taken several and always neck shot. It?s pretty much hit or miss,....a quick small metallic klink always get them to stop head movement long enough to break a shot.

Trapr

WHERE IS THE HIGH WING BUTT ON A TURKEY?

Top edge of wing when it?s folded at rest. Where it?s shoulder would be, at the bottom of the neck. Which is why I call it a low neck shot.

Trapr