FBM delrin trigger
AM O-ring feed neck
it does not chop. It does not cop paint if properly broken in.
Beaks due to blow back unless a modification is done (read review).
I'll cut to the chase, this bolt will break paint in your loader but will not chop a ball in the breach. The JaM bolt is highly efective in preventing chops, but brings it's own set of problems to the table. As with other pbreview members is have experienced ball breaks due to blow back being vented up into the feed neck and into the loader. I've played with my Dwell settings and have had some minor sucsess in reducing the breaks, but breaks still occur.
The solution to the blow back issue is fairly simple. I have drilled two 1/4'' diameter holes into the neck of my eggy (the part if the neck exposed above the marker's vertical feed) and have had no problems thus far with blowback. I have not had time to extensively test this modificaton as i have only had half a case of paint through the mod and a total of 2 cases through the Jam bolt.
To the best of my experiences I have found that you must find a way to vent blow back or your marker will break paint. I am content with the preformance of the bolt (with the blow back mod) but I do not have the confidance against chops like I would with a beam break eye. until I have the confidance in the setup to tear into the trigger (which can only be gained with extensive testing) and the fact that I had to mod my loader to vent blow back, I can only give this product an 8 out of 10.