Wow you know that clears so much up. I never really looked for how the m2 bolt was made but it makes total sense now why it doesnt slide nicely and why so many people have problems with those sail orings leaking, I personally have problems with the bolt not cycling when its first aired up in any weather and with the lpr set crazy high but once it breaks and starts moving free it is fine all day.
I tossed my m2 bolt in my little china mill and stuck a dial indicator on the side of it, measured at the top to see the machines runnout, then where the threaded section was then all the way down at the tail. Its not concentric by 1/32" and mine isnt one of the markers that has tail sealing problems. For relative measurements I grabbed an old first gen image 1 matrix bolt and at the tail the runnout was about 1/3rd of the m2 tails runnout.
I am posting up this video, it is set to only show for people who have the link
https://youtu.be/aB7YiGE_k-8
I'm curious do you guys have a concentricity tolerance at dye? Any paintball company? I dont know if its so out because of how the threads are made or if the machine is pushing to fast without enough stock support but something is making it off pretty drastically. I am going to try and straighten the tail of my bolt and see the difference in drag because of it, maybe solve my gas up issue. It is surprising none the less as I have run a dial indicator on a few ul backs and they have always been dead money in my experience so its a little shocking that a turned piece would be that far out
It has me curious, when I get some time, I am going to try and measure up some more bolts to see how straight companies are keeping things.
I'm sure there is an acceptable threshold for concentricity but 1/32" seems pretty excessive if we are looking at high end markers to have better performance than the lower end models.
I bet the DSR bolt engine has less drag because that bolt would be easier to keep concentric.