Ammo holder on belt, RHS.

But where I hunt I'm not wearing a coat like you.

It's a hard one, Maybe you could have an ammo holder
in your pocket where it is kept dry ?

Or wear a belt OVER your jacket with the ammo holder on it
so you still have quick access to the ammo ?

Or sew a couple (2 - 4) of ammo loops into the outside of the jacket where you can get at them easily ?