Hi All, Just thought I would share my experiment in smoothing out a brand new CZ 550 in .458 Win Mag.Please note this is what I did, it is not intended as a definitive how to guide, use this information at your own risk ! I may add or change things as I think about them. I searched the internet and couldn't find many details of what parts to polish and I may have left out something. I avoided the valve grinding paste/toothpaste method because I didn't want grit in my trigger/ejector/safety etc. Stage 1: This is what I have done so far, there may not be a Stage 2 because this has worked pretty well. I sat and cycled the action while looking to see what made it feel tight/gritty or hesitate. I also dropped the magazine and follower out- This made a huge difference. I examined the bolt and could see some marks/scratches from cycling the action. I decided that the magazine follower was the main culprit but the bolt could also smooth up, especially in certain key areas. I used 600 grit paper without fluid and a sanding block to keep edges sharp. In the picture below, you can see the angled corner (at my fingernail)with a chamfer on the left. The bolt rides up the chamfer and along the corner as you cycle it. I polished the left edge,chamfer and length of the corner with 320 and then 600 grit. I also polished up the sides so that the follower will ride more smoothly in the magazine. Using 600, it is pretty hard to alter any angles or mess anything up. Next I tackled the bolt. One key area is shown by my index finger. This edges rides up the chamfer on the follower and then the corner of the follower rides along the bolt from this point. I polished the edge and along the bolt with a block and 600 grit. You will see it is right next to the ejector slot. I then polished the whole bolt length with a block, moving the extractor side to side to reach the whole surface. I didn't try to remove the radial marks from the manufacturing process, just knocked off the tops of the ridges. I took a little time on the top and bottom surface of the lugs (not the back so headspace could not be changed) Again, not to remove the machining marks but just to smooth them out a little. You can see where I sanded by my thumbnail. I polished the cocking surface, shown by my fingernail. Lastly, I lifted the back of the extractor and slid some 600 paper under it and worked the extractor back and forth to polish the under side. All of that done, I washed the bolt down with paint thinner and re-assembled the bolt, oiling as I went along. The bolt is much smoother and I am really happy with a quick 1 hr job.I have read that I may need to polish the extractor hook because it helps the rounds slide under it. I will leave that until I have cycled quite a few rounds through the action. I am still considering whether I will tackle polishing inside the action and doing the rails so there may be an additional Stage 2 but I am concerned with getting grit in the trigger/safety/ejector mechanisms.