Best and easiest fix is, try GOOD ammo. I was at the range once and saw a guy thoroughly disgusted with his autoloader, as it would fail to feed and stovepipe every 3-4 rounds. I looked at his ammo (cheap overseas stuff) and told him to get a box of Winchester ammo at the range store. Next time I walked by he was having a great old time... and had 3 empty boxes of Winchester ammo!
I had the same problem with some surplus Turkish 9mm. ammo in my Dad's P-38. Got some Remington ammo and had no more problem. (Plus the Turkish ammo was almost as dirty as black powder!)
While I'm on the soapbox... Does this display the same problem with everyone who shoots the rifle? I don't think this should be a problem... but a friend of mine, very lightly built, had similar problems with a .380 Davis. He had a very light grip on the gun, and I held it like it was a brick. His grip was so light, the gun would not cycle! So have some one shoot it who has a very firm stance and see if he has the same problem.