The chamber I cut for my 7.62 x 39 in the Mauser will not extract steel case cartridges does ok with brass cases. The steel sticks and has to be removed with a rod altho it does not take much to knock it out. Apparently the chamber is too tight for steel, this is the first time I had this problem with a chamber. Its headspaced and polished according to what is required.
Is there a different reamer for steel case or I wonder if the rental reamer I used is worn. I did use the correct pilot for the bullet and it was a factory 7.62 x 39 take off barrel. Shortened and rechambered.

Some (or all) of steel cased ammo is lacquer or polymer coated to prevent rust. This can cause sticking. I'd also bet that SAAMI specs for the cartridge are slightly different for commercial ammo/chambers than the military/arsenal specs. And yes, the reamer may have been worn.

The reamer I have is a tight reamer made for commercial use and some military ammo will not even chamber. Mine was made before there was a SAAMI standard, I think. Possibly yours is like that.

I have been told not to use steel cases in rifle or pistol. dunno, but I never had any reason to use steel cases..Any commnents on this.

The use of steel cases has nothing to do with it and anyone who said not to use steel cases is misinformed. Russia and China use them by the billions; brass is expensive. The problem is not that they are steel; it is that they are fatter than the Clymer reamer (the one that I have anyway.)
If steel didn't work, no Nation would arm their forces with them. Reliability is sort of important in combat.
The US made and used some steel cases during WW2. The Germans used them for most of the war. And we use them now for our tank ammo (which I managed in one of my jobs) which operates at a lot higher pressure than any rifle; they work fine.

Steel is less malleable than brass and may not retract after the pressure subsides like brass might.
Mic. a fired brass and a fired steel case at the shoulder and base and compare them. Only 2 or three thousandths of variation between the two will make a difference in a tight chamber.
A couple of my rifles have match grade chambers that are tight. So tight that a fire-formed neck sized reload (brass case) will barely chamber or not chamber at all. New brass, no problem.

I shot a lot of steel cased 45 auto years ago.
Had a friend that reloaded it, said it lasted a long time. I always had plenty of brass cases, and worried about scratching my dies with any grit on a steel case.

The steel used for cartridge casings has properties much like cartridge brass. If your fired case, brass or steel, expands AT ALL at the base, your running too much pressure.
Steel is supposed to be OK but I notice a definite difference when charging AR mags with a stripper clip. Brass is always easygoing, while the steel is balks a little. Like a horse that dont want to go through a gate. You can get him through, but you might have to work at it.

I shot many thousands of steel case ammo in weapons designed for them SKS's Ak's no trouble.

I have seen trouble using steel cases in AR's.

We wouldn't allow steel cases in our Patrol rifle classes as we started to spend to much time helping students un jam their AR's.

I know a guy that reloads steel 223.

I unintentional ran a steel case into my carbide 45acp sizing die broke the carbide sizing ring.

JFYI

Brass expands and relaxes after firing for extraction. Steel cases expand, but do not relax as much. In a tighter chamber, steel may easily feed but can cause extraction problems. Most military chambers are pretty sloppy to ensure they can eat steel cases.

While parts between various AKs manufacturers are designed to be interchangeable, it's not due to precision milling. Quite the opposite really. That's why they're battlefield reliable.

I suspect, as you mention that even brass cases are "ok", that you have a nice, tight chamber - as making millions of ak's is hard on tools, the russians did, and I expect others have, started with a slightly oversized reamer (to their specs) and used then sharpened until it was reduced to spec - why? semi auto battle rifles can not jam due to ammo chamber mismatch

therefore, if you have had the chamber cut, the smith didn't likely have a "sloppy" er, oversized reamer, and I would suspect steel cases wasn't mentioned.

all the feedback on expansion and paint is also likely correct

you could try using some steel wool to remove the paint/lac from the cases and see if it functions any better

then you'll need to decide if shooting steel cases is import, and then decide if you want the chamber recut

j