I have a pre-ban colt and recently bought 2-30rnd mags. for it one is a FN the other is a Colt, finish worn off of both. When i  try to release the colt mag from my ar it does not just fall out like the FN or the colt 20rnd mag. Is this normal and if i refinish these mags. will I have even more problems with the colt sticking. any info would be of great help

Do you have a caliper?  Measure the rear of the drop-free mags and compare with the measurement of the mag that won’t drop free.  I bet the mag that won’t drop free is a little wider towards the rear of the mag.

Over time, mags will start to spread out a little.   You don’t really need to measure the mags to see it.  Remove your upper from the lower and insert the mag.  You’ll be able to see (or at least “feel”) where the mag is too tight.  

I recently fixed this by laying the mag on its side, placing a piece of 2X4 across the top of the mag and tap the wood gently with a hammer.  Tap once or twice then check the fit of the mag.  You might need to tap a few times.  Take caution not to place the wood over the mag catch hole, since it is partially raised.