the problem with feed failure is not so much low power ammo. The darn slider on the all-plastic mag sticks - plain and simple. When you fire a round, a sticking magazine follower wont rise up to feed the next round. The bolt closes with no round in the chamber.
Don't oil the mag! It will gum up even worse.
The mag can be repaired, but you need the right materials and you have to take it apart. Disassembly of the mag can lead to breakage of the plastic limiters (for 10 round mags) so BEWARE.
What you need is fine POWDERED GRAPHITE. You can get this at most hardware stores. You want to take the mag apart, wipe it clean inside and out. Then apply the powdered graphite with either your finger (use a rubber glove) or a Q-tip to all the interior surfaces. You want to take a little bit of powder and spread it on the parts with the Qtip till they are shiny black. Do this for the inside of the mag, the follower, everything. Reassemble the mag and cycle the follower up and down. It will feel smooth and responive.