Sometimes there is no hole in the drum to adjust the shoes. If you look closely you can see the outline of it and you have to knock it out with a chisel. Then you can back the adjusters off thru the hole. By it coming out a little ways then stopping, it sounds like the shoes aren't backed off. If it's stuck solid and doesn't budge, you can heat the center of the drum with a torch and break the rust loose. The cast drum will expand at a different rate than the steel axle, causing it to loosen.

'65 C-10, 65 L-60, 65 C-80, 72 C-60 & and a bunch of old Chevy cars.
Never time to do it right, always time to do it over.