Just an update. I recently did a Tracker and it strips the same as an Osprey (check earlier in the guide). The only differences I could see ( in the strip) is that the Tracker had a piston weight in it and had a seal on the front of the piston head instead of the 2 ptfe rings of the Osprey. On the gun I did the safety catch was missing and the sear spring. I replaced the sear spring with one from a Webley Victor, which hooks under the trigger pin. You could use this mod if you want to leave off the safety catch on a Hawk mk2, Hawk mk3, Vulcan and Osprey. As I dont like safety catches anyway, especially automatic ones, this seems a good idea. I think the added bonus will be that the sear spring will last longer as the catch is not "sawing" the spring like normal, where it hooks over the catch. It also makes the trigger a lot easier to assemble and you can leave out the front of the three pins and keep it as spare.