Luger problem

[gundogblue]

Hi All,
Im brand-new here, and new to Lugers, first off, I've been shooting 1911's all my life and I know absolutely nothing about Lugers, I've never even held, or shot one until last week-end. A good friend of mine inherited a 1916 Erfurd Luger from his father, it's a real nice gun, it's a low serial#, there is no letter prefix before, or after the serial#, and all the numbers on the gun match. The only things that are not original is the magazine (it has a white plastic bottom, and no serial#) and the grips. The gun has been re-finished at some point, but it was a very good re-finishing job. I was told that Lugers need to be shot with "hot ammo" I dismissed that idea when I first heard it, I don't shoot hot loads out of any of my guns, I just don't see a need for it. We took the gun to the range last Friday, the ammo we had on hand was Winchester white-box, UMC, and my hand-loads which are 4grs of Bullseye behind a 115gr round nose bullet. The luger would'nt fire two rnds in a row, the gun would either stove-pipe, or fail to eject the empty case from the chamber!! Could I be wrong, do Lugers really need hot loads to function properly, or are we dealing with some other problem? Im trying to help my friend, but it's like the blind leading the blind, as I've said I know nothing about Lugers except that we were able to fire one shot at a time, and I was amazed at how acurate that little gun is, at 10 yrds, I could put everything in the bullseye. Any help on this will be greatly appriciated.
Paul