There's a small issue with this mod where inserters are fussy about loading ammunition into wagons if the inserter was placed into the game world before the wagon. Wagons will reload just fine if they pull up to inserters that were placed after the wagon; it seems that rotating the inserter and then rotating it back also fixes the issue. This is a relatively minor frustration, but I think this mod would be perfect if this issue were to get fixed; I really love this mod otherwise and frequently use turret trains to cover remote areas.

The inserters are otherwise properly positioned onto the center two squares of the train cars already and are using vanilla ammo, so that isn't the problem.

Same issue, temporary solution found.

Stop platform on a curved rail, place inserter two tiles away from the track, so it loads items onto the hitbox of the turret, not the train.

Ver 0.4.6 used with SE, Krastorio and 30 other mods

Following attempts did not work on straight tracks with vanilla ammo/fuel:
-Loading platforms from both verticle and horizontal does not change the failure
-Loading platform from all 12 sides
-Used all vanilla inserters
-Used circuit logic to turn inserters off and on
-Loading platform after train has stopped at a station

Following attempts worked:
-Rotating orientation of inserter
-Replacing inserter

Inserter displays 'Waiting for space in destination" during all failure attempts

Just tried this out and the curved rail approach does work...too bad I'd have to redo all of my rail stop blueprints to get it to work...