Cartridge Shell

Why did my cartridge get stuck in my rifle?

I read in a hunting magazine that it is a good idea to put an empty cartridge in a rifle to keep oil and dust from getting in the Receiver and gumming it up, so when i cleaned my 30-06 i did that and i put a shell in clip(its kind of hard to hand load it on mine) pulled the action back and let it slam closed like your suppost to. But then i tried to open it and it was locked shut and i was worried i would break it from pulling on it so hard so i rammed a rod down and i finally got it out. the chamber is clean too.it does this on every cartridge i try. WHY DOES IT DO THIS?
The gun is a Remington 740 Woodsmaster 30-06 semi auto. 1955. if this helps. and it has no problem chambering unfired cartridges.
To lana san, the action does not make a leakproof seal and oil can leak back into it and gum it up.

The case expands when you fire it, especially in the areas of the case neck and mouth. The chamber is slightly larger than a sized unfired cartridge, and when fired the cartridge’s case expands to fill the space. When you left the bolt go, you basically sized the case to the exact dimensions of the chamber and force-fitted to the chamber. That’s not usually a good idea.

I had the same problem when I was checking re-sized cases in a bolt action rifle and found one that hadn’t been resized. I was talking to a friend and didn’t look closely at it. The bolt closed and then was really hard to open, luckily the extractor held and pulled the case out when I heaved the bolt back.

How to fit the cartridge( needle / stylus) to the head shell