'Evening all,

I’m puzzled by some unexpected results from my 0.177 TX200SR Mk2, and wonder if someone more knowledgeable or ‘SR experienced’ could replicate and/or explain them.

I set the slide bolts evenly such that the action just moved when the gun was held vertical as per the instructions in the AirArms TX200SR manual, then chrono’ed it without a ‘scope fitted giving an average of 770 fps.

Then I thought “should I have set the slide tension and chrono’ed with a scope on?” as the recoiling mass would increase by the mass of the scope and thus increase the muzzle velocity (‘scope is an old Mamba Lite). Searching the internet counter-intuitively left me with the impression (against my intuition) that any difference would be negligible. Chrono’ed again and an average of 800fps. Too high for me.

Before taking the SR apart I re-chrono’ed but with the SR’s action held in the forward position so it couldn’t slide backwards. An average of 775 fps.

The action started at the same forward position and didn’t recoil to the end of its travel for any shot. Slide bolt tension was unchanged throughout. Chrono was checked against a combo on each occasion. Gun operates smoothly, is consistant and accurate.

So, what to do now? I’d appreciate it if anyone with a TX200SR could do a similar test to see if they get a similar effect, or educate me if “it’s all been done before”!

Best Regards,
Bill.