MCarbo stood behind some problematic spring /trigger upgrade for the Ruger PC Carbine in the end. I ran into severe hammer follow leading to a dead trigger with their spring kit which they no longer sell. They sent me a prototype disconnecter to try which was awesome, but it lead to a double fire problem which is a major safety issue to me. They asked me to send them my rifle so they could troubleshoot it. We had a few crossed wires in communication about the return of my rifle and I'll take some of the blame here. The solution was to make the bolt carrier heavier and they were going to make me a tungsten charging handle. When my rifle arrived, the tungsten charging handle was not with the gun and there was no explanation. When I talked to the gunsmith, he said his note must not have been included with the gun but that the charging handle was waiting for its coating. A few months went by with no communication. I checked in and had got the same answer. I checked in again as another few months went by and a different gunsmith gave me a straight answer and said the tungsten charging handle was breaking the screws (I assume the charging handle screws) and that there was no solution. I appreciated the straight answer and we agreed on a refund which was processed quickly. When I pulled the trigger assembly out to remove the MCarbo parts, my gun was filthy. I got the feeling that MCarbo used my rifle for their product development, which is fine, but I sent them a spotless gun and received a filthy one. I have never received a dirty gun back from a gunsmith - whether the gun was getting upgraded or repaired. I feel a bit like I was left holding the bag on this one until I got the straight answer from a different gunsmith. I have had a lot of great experience with MCarbo. The are a veteran owned and operated company and I want to support them, but I am going to wait for a while before I try them again.