Welcome to MIA and thanks for your service, hope you enjoy the hobby.
One thing I wanted to mention before getting into the question take a minute to read the rules on the forum, you can edit posts by clicking the "modify" link in the upper right of your post rather than posting a second time immediately(double posting). Also we're somewhat formal in the sense that we try to keep the writing here with punctuation etc. So going forward I'm sure everyone would appreciate a little more punctuation and capitalization, I know it's rare on the internet these days but it does make things easier to read for everyone.
On the gun spring sniper rifles can be as much time as money to upgrade and get to a level that you really have a range advantage over the typical AEG's on the field. No matter the parts involved your going to spend allot of time working out all the details to get it working the way you want. Even with the time and money sunk you'll find that while you have more range it's not a huge amount over an AEG. Just a warning of sorts, it's a fun role, I play it a fair amount of time but compared to real ballistics airsoft always falls short of expectations;)
Like mentioned above most outdoor fields where a sniper rifle will be useful will have FPS rules that will allow basically sub 550fps guns. Generally at around the 400fps level with everything working properly you'll find you have a maximum accurate range of around 75 yards. If you upgrade the internals to support a stronger spring, and do allot of work with the hopup you might be able to stretch that past 100 yards but not by a whole lot usually.
On silicone, you can order it online fairly easily or RC shops will carry silicone for shock oil which is fine for airsoft use. Do be careful how and where you apply it though because you don't want it getting into the hopup chamber or you will loose the ability to get backspin on the BB making your range drop off dramatically.
Take care!
Luke
