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RKG's correct - the inside leading edge of some loading gates have a too-abrupt angle, to cam the last shell loaded into the mag a bit forward when the nose of the next shell to be loaded pushes the gate "in".
Your loading gate might need to be smoothed/stoned on it's inside leading edge.
If you polish the gate where the rim rides against it when loaded, it will load easily (as it should).
There shouldn't be the slightest problem with topping off the magazine at any point, and even pushing each round all the way in when loading.
Many guns bind on the shell and its hard to push the gate open when the round is all the way in.
Many accept it as "normal", but it shouldn't be binding like that.
Older 94's (pre-war and earlier) load slick as can be at any point, and yours can as well.
(I always push each round all the way in when loading and have no trouble loading more.)
The little short angled rib part at the forward end, on the back side of the gate, (with the blue polished off) and the back edge of the half moon shaped part of the gate, if you break the sharp edges off, and give it a nice polish, should allow the gun to load easily no matter how many rounds are in it already.
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