Got my Rpaid mk2 Fac finally yesterday. Just got a few questions about it,

1 is it normal the noise makes when im charging the bottles? It makes this real squealing, whistling type noise, none of my previous rifles done it. Also I have two bottles and one of them doesnt seem to hold air well when charging and it drops away back after you stop the filling (I know it is normal for it too drop a bit but it drops from about 220 to 160 bar) also when filling this particular bottle the neddle on the presure guage bounces all over the place this doesnt happen with the other one. Also when screwing this leaking bottle onto the rifle it doesnt seem to stop tighteing up whereas the other bottle has a good positive stop when its screwed fully in. Any ideas?

2 whats the optimum filling pressure for the 400cc bottle? I got no instructions with it so Im just going by what I have heard, also what is the proper procedure for taking the bottle off at the minute im unscrewing the bottle a bit then firing a couple of shots, then putting the bolt into the back postion and unscrewing the rest of the way. Is this right a friend used to have one and I think this is how he said to do it. Also when im putting the bottle back on do I keep the bolt in the back position? When I screw it fully home I can hear a puff of is this ok?

sorry for all the questions I just have very limited experience with these rifles and no instruction manual, ps the rifle is amazing so accurate. Thanks for your help any other suggestions on looking after them basic tuning etc much appreciated.