What a polite young man , what a breath of fresh air that is !!
Good evening Josh , welcome to the forum . Im sure you`ll know alot so far , but join in , have a chat , and have a laff along the way , Bust .
To be fair , the last thing you need to be doing right now is taking the gun apart , especially as someone suggests it may be a seal. There are loads of causes for this , and i think the best thing you could possibly do is take the gun and scope to the local gunshop and ask their opinion on why your having these problems. They will have much more experiance than you and chances they will have you sorted in less than an hour .
Quite a few differences , in fact too many to just read about . Best thing is go and try em both out , ive had both and did`nt like teh 510sl , but ive had quite a few S4*o`s . Pick em up , have a shoot and see what you think , Bust .
The only Air Arms rifle that was sold with factory `camo ` was the S300/S310 Forester .
As already stated , this is an aftermarket `hydro-dip`
Buster .