Just cracked out a new AR2078A,

Didn't have much time to work on it tonight but did do some testing, Raw with no clean up other than the barrel it was shooting about 690 with Lasers, after alittle cleaning of the internals and adding 2 washers to the valve in an attempt to slow it down a little, it's now shooting about 685 with JSB match ,and about 710 with the Lasers. Gonna have to do some work to get it down to 550 for match shooting. I'll let you know how it goes. Mike

[Wallis]

Mike,

Where did you add the washers to the valve. I have not hear of that, All i have heard of is shimming the hammer spring.  inquirng minds want to know

Disassemble the valve and stack another  one or two on the one inside there, you will have to remove the sleeve to do this and can't put it back in. Doing this will make the rifle velocity more stable, it can rob a few FPS but if stability is needed thats how i do it.

I was able to detune the rifle somewhat by adding some washers on the back side of part #200, it's the block the hold down stud screws into. The stroke on the valve is now about 1/32 of an inch and has the rifle shooting in the high 500's. I lost count of the shots on this fill but it's been a bunch, when it emptys out I'll finish the work on it and see what it's shooting. The deviation from the average shots is around 1 to 2 fps with out of the box pellets so it will be consistant. The groups I've shot out side with a light breeze has been around 1/2 inch at 20 yards using the diopter sight on the rifle, get the barrel broke in and a good shot behind the trigger and it will be fun to see how accurate this thing is.

[Wallis]

Thank you mike for the info. I never knew that.  sounds good on the rifles. esp. the stability of the shots.

I just completed some testing on the detuned AR2078, I charged the rifle with one cylinder and then shot two strings of velocity tests. Came in with 580 with CPL's and 610 with Beeman Lasers. That's twenty shots, then out to the twenty yard test range, gusty winds at 10 to 15 mph. Groups of about 1/2 inch with the CPL's and about 3/4 with the JSB match (didn't like the wind) after 10 targets with 5 shots on each the poi dropped about 1 inch but continued to shoot another 3 targets. With the velocity so slow all you hear is the hammer hitting the stop block and the pellet hitting the target.
With a full charge of two cylinders it looks like a complete match could be shot without recharging.

I wouldn't call that a detune. I'd say it was an accuracy,or eficiency tune,rather than the power tune many go for.