What caliber is the chamber of your barrel? .223 or 556 or wylde?
edit: I just looked on JP's site. It seems they are wylde chambers. Which is the reason your 5.56mm cases are getting stuck.
I haven't had any trouble with a stuck case in 5.56 in the past in my JP. I also haven't got it that hot either.
The M&P is a 5.46x39mm and the steel cases stuck in it too after it got really hot.
Edit: I just checked the Tula ammo and it is 223 Remington not 5.56.