Gas Sniper-WELL 96 338

[Chandler]

Alright girls and Lads.

Just acquired a gas L96 ( Chinese clone ). Its got a V2 madbull tightbore ( very slightly longer than original ) the barrel is already shimmed so it has no wobble..

Using propane and putting 15 rounds through chrono it went from 550 to 410.. i'll replace all the o rings etc with new as the others are probably cheap crap. I'v replaced the hopup rubber and the nub ( tried an SCS Curvy thing and a normal nub which is quite thick )
But the hop seems perfect for a few shots and then its all over the shop again.. hitting planes sort of thing!

Never had any experience with a Gas sniper so im very new to this.. any suggestions?! want to get it consistant at about 470 ( my site is 500 ) so i'll be fine with that.. lots of lube etc.

Any ideas? tried using .3s and matchgrade .25s... and again hop is very inconsistant.. worth me changing rubbers? its running a systema rubber atm.. AEG rubbers fit fine.. i take it these are the correct size?

Again i dont want to sound like a noob so i apologise.. this is nothing like my GBB WE Scar! lol..

Thanks in advance