Had my Prod for 6 weeks now and finally got it tuned. Put a Hill moderator on as well as a Allen butt pad to lengthen the shoulder stock. The cheek pad in the attached photo came off a Savage 110 Scout rifle I modified. Other than those additions I have not modified the gun with any new internal parts.
I started my tune after watching a You Tube video by (airgunenthusiast) "Episode 1 - Tuning The Benjamin Marauder Pistol"
Before making any actual tune afjustments I backed out from the factory tune position (hammer spring tension using 3/16 allen, 2 1/3 turns ccw to end of travel) (Hammer throw using 1/8 Allen, 1 1/2 turns ccw to end of travel)
From the full backed out position I ended up with a Spring tension setting of 4 1/2 CW turns and a Hammer throw setting of 2 CW turns from the full back out position. One thing I noticed is that the hammer noise lessened as I got closer to my final tune position. I doubt I would have noticed this if I didn't have a moderator on the gun.
You cannot make informed tuning adjustments without a chronograph and shooting shot strings to evaluate the adjustments you have made. I started out making half turn adjustments and when I thought I was close I went to 1/4 turns. I ended up with a 1/3 turn adjustment after shooting for accuracy and cleaning the gun on a second day of chronographing.
These final adjustments gave me an average of 687 fps with a JSB 13.43 gr Match Diablo RS pellet, 14.1 fpe and 24 shots before accuracy suffers and air refresh is needed.
I am happy with the pellet speed and shot count. The fpe is plenty for squirrels but accuracy is most important. Attached is a photo of a 5 shot target at 30 yds. Note that there are two holes, the lower hole has 4 shots and the 5th shot a little high but touching. I have been shooting at a 20 shot, 25 yard benchrest target(at 30 yds distance) when the weather permits and my high score is 193. That's 7-9s and 13-10s. Gotta admit I'm happy and having fun.
Cheers
Chase