Do not oil the feed ramp of the barrel. Glocks barrels are tennifer coated inside and out and do not require oil. In fact, oil will collect powder residue and cause you a problem in this area. Use very little oil and only in the suggested places per your manual. With Glock pistols, less is better. Also, do not polish the feed ramp as it is not required on Glocks. you will be defeating the tennifer coating. Instead check your magazine for any unusual conditions that may appear to be abnormal. Remove the base plate and with the spring an follower inserted, hold the mag upside and you should see at least two coils above the bottom of the mag. If you don't, you have a spring issue. If you do ahve a spring issue, call Glock for warranty service if the gun is new. If not, get a new mag spring and install it.