The Mosin loads reasonably well with decent stripper clips. The ones I use regularly haven't given me much trouble at all. Using the clips well takes some practice, more so than Mauser clips I've found.
Some things I've figured out with my Mosins:
1. I load my clips in a 'mountain' shape where the middle round (#3) is sitting highest, the adjacent rounds (#2 and 4) are lower (rims below the middle round), and the rounds at the ends of the clip (#1 and 5) are lowest (rims below #2 and 4). It's hard to describe...I'll take a picture tomorrow of what I mean because I don't feel like digging everything out now.
I don't use the 'staggered' method like everyone says to do....it's a pain in the ass to handle (bottom round can flop around), and the clip can only go into the rifle one way, unlike how I set my clips up which can be inserted either way.
2. Lifting up the first round (like in the video above) helps get downward pressure on the rounds, specifically the rims
3. You need to get the rounds down in one motion...if you stop part way through you'll have issues and they'll just bind up, or the clip will start popping up out of the rifle