Tuned my gamo big cat whisper 1300

Hi all, i believe this is my first post in the springer forum. I have a.177 big cat whisper 1300 i got for my birthday a year ago. Never really liked shooting it because i thought it was under powered.
I remember reading somewhere, don't recall where but I read that a lot of the gamo rifles come with the piston seal torn from the the factory. So i ordered the av spring compressor and took it apart for a tune. This is my first time tuning an air rifle. Well sure enough the seal was compromised.
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I filed all the burrs and sharp edges sand and polished the compression chamber, put moly on all metal to metal parts, replaced and lubed the seal.

It was shooting the 7.9 grain crosman premiers 580 fps. I will test it tomorrow and give an update.
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I have not had the right combo of free time and weather to do a chronograph string but i did shoot a group today when the wind died down a bit. 5 shots at 50 yards .7120 inches using crosman premier box 10.5 grain. Im happy with that can hit a 1" spinner 4 out of 5 shots at 60 yards. The few readings i got off the chronograph was 725 752 731
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