Suomi kp31

Bought a Suomi awhile ago, and finally got to get to the range. Its a heavy gun, almost no recoil. Its a pleasure to shoot, I could have shot this all day. It ran well for about 150 rounds then started to jam. I noticed that the bolt is parkerized, i'm thinking as it heated up it started to stick. I might try to polish it and see if that helps. (any imput would be appreciated) I was using stick mags and coffin mags. I like the quality of the build, parts fit well and the welding job is very good. Im glad I bought it. Here is the Suomi, and me shooting it at my range. It was a fun day.

http://i6.photobucket.com/albums/y206/jd46561/DSC02130.jpg
http://i6.photobucket.com/albums/y206/jd46561/DSC02127.jpg
http://i6.photobucket.com/albums/y206/jd46561/002.jpg
http://i6.photobucket.com/albums/y206/jd46561/001.jpg

A friend of mine had one of these. It had issues with the extractor - it broke very easily. He ended up selling it. I hope you aren't having the same issues because those are some neat guns.