Can anyone please point me to some sites which can give me the best angle for maximum projectile range?  

If you know it through experience/whatever, could you please give me details on the angle, and possibly IM me your qualifications/experience/whatever?  I need to document the info I get, and want to get a wide range of sources.  I know artillery guys should know some things about this.

Any help will be appreciated.  This is for uni work and I managed to sneak in projectiles and stuff .

From a physics perspective, maximum range is achieved at a 45 degree angle to the horizontal.

Here is a little info on the subject.

www.loadammo.com/Topics/May01.htm

45 degrees works if air resistance can be neglected.

If air resistance has to be considered, the angle will (usually) be lower (you want greater horizontal velocity to overcome the air resistance).

After that, "It Depends".  You will need to account for all the stuff which is neglected when one says "Neglect air resistance) - air density, humidity, temperature, changes in these with altitude changes, projectile shape, etc, etc, etc.

IBT Fizassist.  

Here's a few simulators, for what they're worth:
http://jersey.uoregon.edu/vlab/Cannon/
http://www.engapplets.vt.edu/dynamics/projectile/projectile3/Projectile.html

Here is a whole page of ballistic simulators.

www.stevespages.com/page8b.htm

But I think this one will give you what you want.

www.stevespages.com/exe/trajectory.exe

20mm vulcan angle