I've ran into this problem too, and I solved it rather easily, as well.
My M44's interruptor spring was so stiff I could hardly get the freaking rounds in it, even one by one. Take the thing out of the stock, and (CAREFULLY!)tweak your interruptor spring out with a screwdriver until you get the desired tension. My M44 will load all 5 rounds smoother than any of my other Mosins now, and retains them just fine-haven't had a problem.
It's a strong spring, but all it takes is a little one-handed tweak underneath it. Just go slowly, and you'll have a pretty soft M44- I know I do
It's lovely when you stick in the stripper clip and bzzzzt! they all float right in there.