u/Notyomama__2

I bought a used Windham AR-15 and haven't had any problems. I shot about 200-300 rounds through it, and then decided to give it a deep clean.

When done, I made sure to lube it liberally. Unfortunately, I'm having trouble with my magazines locking in.

It seems as though the carrier is a little low? I've tried adjusting the mag release, old mags, new mags, full mags, half-full mags, and nothing is working. Empty magazines lock in just fine. It seems like with any amount of bullets in a magazine I have to compress the spring like 1/2" just to get it to lock in. It runs fine once the magazine is in. It's just TOO tight. Any ideas?

Edit: I think it actually had to do with either the magazines or the frame. The one on the left is a brand new magazine. I pushed it in and out of the lower receiver 20-30 times with the mag release retracted and it’s dragging. (photo in comments)