Embarrassing newb 870 question

[MK11]

This is probably an eye-roller, so I appreciate your patience.

I recently picked up an 870 Express HD Tactical. So far it's run well but I'm having issues loading to full capacity with the slide forward and the loading gate down. When it's down, I can get four in but the loading gate won't push up far enough to allow any more into the tube. With the slide retracted and the loading gate all the way up, I can easily load the full six. A round is NOT chambered when I push the slide forward, but the trigger is cocked, which makes me nervous. All this was tried out at a range with the shotgun pointing down range.

Is the 870 supposed to be loaded with the slide retracted? My only previous shotty experience is a Mossberg with no loading gate.

[Dfariswheel]

A possibility is that the slide handle is moving to the rear about 1/2 inch while you're loading it.

With the gun un-cocked you can pull the slide to the rear slightly. With the slide back that small amount, you can't load the gun.

Try loading it while holding the pump handle all the way to the front and see if that corrects the problem.

[Wyosmith]

The drill has always been like this;
1 Open action fully.
2 Place safety to "on" position.
3 Drop shell into port and close action.
4 Load magazine fully.