None that I can think of, possibly a Delrin bolt when they become available
Realistic, accurate out of the box, intimidating on the field
Needs a little tweaking for maximum performance
After looking at a number of realistic mil-sim markers, I decided to go with this product. It has a very distinctive sound and look, and aside from a cocking pin problem it has worked great in the field. It has a hefty weight to it, so a sling should be mandatory, and if you don't want to use the remote nipple connection you can screw in a tank directly to the rear. The great thing about it is it can take any attachment that a real M4/M16/AR15 has and just connect it to the marker, no mods needed.
Recommended for those that want the mil-sim feel, and are willing to take care of the marker after using it - it will work well if not abused.
So a marker you had a cocking in problem with, is so heavy you recomend a sling and that you said "needs a little tweaking" you give a 10?
Just becasue you paid some money for it don't be blinded.
It's just a mediocre marker.
You may see the light some day after you have had a chance to use a few decent markers.