I use the built in feeder lip thingy on speed loaders. The clear one that came with the rifle way back when seems to have the lip thingy glued in place to the loader.
I've handloaded too...but only when I couldn't find my loader...
I usually strip 1-2 BBs off as well. Stuffed full there's zero compression to the stack of BBs and when you slam that mag in with your bolt closed. With 1 or 2 taken out, there's enough give so as not to risk damaging things. By no means proven one way or another...just makes sense to me.