What's nice about the Turkey Shoot scene is there's time to actually look at the lock.
They were using long rifles with percussion locks. But if you look closely, you can see some big ole' chunky hammers. Like military hammers.
I can't imagine Hollywood using real deal antique rifles to shoot those scenes. Even Hollywood would understand the value of those guns. But assembling guns to use in the movie is a definite possibility. There was no DGW or Lodgewood or TOTW back then.
Just some creative Hollywood armorer/gunsmith, deep budget pockets and a pile of surplus parts. Love...it!