Air Arms T200 tuning: a method to this madness?

[Skillet]

Hello all!  I'd been enjoying my stock T200 (CZ 200) target rifle and decided to increase the power as described in the Pyramid Air catalog.  They made no mention of how much adjustment to make, so I went two turns on the air transfer and turned the valve hammer screw in one-half turn.  I don't know what I'm doing. 

Right now it shoots much louder and hits harder, but I have no chrony info as of yet.  I feel like a cave man doing this.  I'm going to stop using it for now.

I'd like to think that there is a "balanced" way of varying the air power and the hammer power, just like there is a balanced way to adjust a two-stage trigger.  I checked in the owner's manual and the GTA library but have come up with nothing so far. 

If anyone has a method they'd care to share, or a link to an existing discussion, I'd appreciate the help!  Cheers!

[LeadBreakfast]

Well, there are two ways...cheap and not as effective, or more expensive but highly effective.

Cheap? Fill and shoot at different setting until POi changes significantly and record settings.

Spendy? Get a chrony

[Skillet]

I have a chrony and what Cam says above makes sense, I'll just experiment and see what happens when I change the air pressure and then change the hammer spring pressure, at max fill pressure.

If you increase the air pressure to the air valve, then you have to increase the pressure on the hammer spring to let a greater volume of air out.  When the chrony shows no more increase in velocity as the hammer spring pressure is repeatedly increased, then you have adjusted the hammer to completely empty the valve at just the right hammer spring loading.

If I record everything and relate increases in pellet speed to the number of turns on the two screws, that might be kinda cool for Air Arms T200 (not TX200) owners.

[Ribbonstone]

With a chronograph, I tend to work in two stages.

STRIKER SPRING ADJUSTMENT: This sets the operating pressure.  While playing with this one, am only trying to get the rifle to run right with a 170BAR fill.  Actually want it to shoot a little slower if filled to 180BAR, a bit of a climb in speed as it falls to 175-170BAR.

TRANSFER PORT ADJUSTMENT: Once you get the fill pressure set up, then opening the transfer port speeds things up (and decreases shot count), closing the transfer port off slows things down (and increases shot count).

Without a chronograph, are pretty much wandering around in the dark.  The sound of the shot is an unreliable judge of velocity. Sound is a pretty good indication of the volume of air being moved at each shot, but the "extra" air may not be going towards pellet velocity.

Without a chronograph, you might find a setting that seems really good and want to see.

Cannot figure how fast, but can figure how many reasonably uniform shots.

About the only way to tell is to set up a line of dot targets, shoot them, and see how many shots you can get before the pellets start landing below the dot.  With a 200T, might need to allow for 60 shots (so maybe 12 dots on a line, 5 shots per dot?).

Idea here is that slower=lower, so once you notice a drop in POI at close range, can pretty well count on a pretty significant velocity change.

OK...picture worth 1000 words.  In this case, maybe 500 words as it is NOT an 200T.  For a 200T, would likely need 50-70 dots to shoot at, the rifle used here isn't liklely to get more than 15-20 "good" shots.



Have ABSOLUTLY NO CLUE how fast it is going from the target.

Do have some other clues.

Evidently it is shooting pretty fast from the first shot.  If not, the hit would have been lower.

Evidently it's starting to slow down by the 16th shot, and definitely slower by the 17th.

So from shot about #1 to shot about #16, the velocity much be stable.

Converting that to the 200T would likely take 4 times as many dots to shoot at, but follow the same idea.

But again, no way to know HOW fast, just know where it isn't as fast as it was.

[LeadBreakfast]

If you increase the air pressure to the air valve, then you have to increase the pressure on the hammer spring to let a greater volume of air out.  When the chrony shows no more increase in velocity as the hammer spring pressure is repeatedly increased, then you have adjusted the hammer to completely empty the valve at just the right hammer spring loading.

If I record everything and relate increases in pellet speed to the number of turns on the two screws, that might be kinda cool for Air Arms T200 (not TX200) owners.

There ya go! It will likely be fairly tedious and a lot of trial and error, but a gun as fun and accurate as the T200/CZ200 is worth it! I think that would be a great resource for all the owners. Just know that though it can be increased, it still won't be a powerhouse. IF I recall correctly (a big if!), I have read that peak efficiency comes between 12-14FPE in these guns.

Best of luck!

[LeadBreakfast]

Just ran across this on the PA site, not sure if useful...

adjust the power you must remove the stock. at the rear of the receiver, just below the bolt there is a slot headed screw. tighten this screw all the way down, now unscrew 1/4 to 1/2 to achieve max power.should take you from about 12fpe to 16.