I used to grease them, but just put them in dry now. Too messy and will collect dirt easily. Also get a spacer or longer buffer to avoid breaking your bolt catch. I made my own from 303 SS and carbide weights coming in at about 9 oz.
Is your 9mm buffer the same length as a carbine buffer or is it a longer version? Standard carbine buffer is about 3.25". Try pulling back the charging handle then push rearward on the bolt to see if it goes any farther than how far back the charging handle pulls it.
You can put in one of these spacers or make one (like I did). Some people just put in a few quarters (I think 8-10) behind the spring. The problem is that the bolt gets too much inertia traveling all the way back and then coming forward breaking off the catch. The idea is to allow the bolt to...
Did you get the double disk kit? It's almost required for the .223 loads. There's a couple powders that might work with the single disk, but it's easier to get it correct with the double disks.
This is what I ended up doing. It will still be shiny unless you bead blast first. I may redo it later and put it in the blast cabinet first to dull it some. But it turned out well.
http://www.mdshooters.com/showthread.php?t=95004
Bolt bounce isn't much of an issue on a semi-automatic rifle. On an M-16, it will bounce as the auto sear trips causing either a light primer strike or no strike at all. On a semi, the bolt will likely return to battery before you could pull the trigger again. But yes, the extra weight will...
They have a Bushmaster C-15 in 9mm on the roster.
Here's the list
http://www.mdsp.org/Organization/SupportServicesBureau/LicensingDivision/HandgunRoster.aspx