Benjamin Marauder magazines hard to load

My 1 year old .177 Marauder has always been hard to insert the magazine into, and always hard to remove the mag. I bought several replacement magazines and they all are hard to push in and remove. Is there any solution to make them easier to load/unload? The bolt is not in the way, it looks like the O ring sticks out just enough to block the magazine from inserting. Really tight fit. Can I sand the plastic magazines to make them thinner? Is there a grease that I can lube the receiver area with? Any advise would be helpful.
Thanks