Carl, back in the day when these were current issue weapons, the Military trained their Infantry to "own the first mile". These old bolt guns, just like the Germans, Japanese, US Army, Russians and all had battle sights that started at 300 m and went to a hell of a long way out.
They were not for sniping, although I'm pretty sure the average good shooter with young eyes could hit pretty far out, rather - they were for "volley fire" meaning arcing trajectories and lead raining down from the sky out to a 1/2 mile at least. Made the enemy keep down and immobile.
Ma Duece and chassis mounted system do that now. So the current rifles are designed to work in closer.
If you are shooting WW-II era rifles and want to use the stock sights, you need to change your sight picture. In side of 100 yds, you could aim for the belly button and get a solid hit in the chest cavity. Aim for the sternum, and you have a head/neck shot. In other words sit the enemies center of mass on top of your front sight so you can watch him and the sight and then pick you best time when he is slowest or still. As the yardages get longer, move you front sight up the target. If you are at 300 m, your POI should be just atop the front post.
There should be lots of information on classic military sight pictures and estimating range out there somewhere?