I wish this posting was more upbeat... but I had the same problems with my '63 M41 with a 5" field barrel and 5.5" bull barrel.
Over the course of 3-4 months I had cleaned it repeatedly before every outting until there was not a micron of anything on the gun except gun oil, changed the extractor spring and got the "calibration spring pack" from Wolf.
After lots of rounds down range I finally came to the conclusion it simply wasn't going to be reliable with anything but high velocity loads.
If loaded with 5 or 6 rounds to start with it would function pretty well but if loaded to the max I'd get maybe 75% of the time it would fail to eject the 1st, 2nd and/or 3rd round of CCI Std. Vel.
On the other hand, my 5.25" tapered barrel Ruger MkII works with everything I feed it and is just as accurate.
Just got tired of tinkering...sadly, the M41 was sold last week.