This gun is not my design,but I have modified it a bit.I have added an attachablebi-pod,grenade launcher and fore-grip.
Good power and accuracyGood scope
Looks goodHigh range
Ram guideTrue trigger
Ram sometimes shoots outTrigger sometimes gets jammed
Other than those cons the gun can shoot 40m (130ft) and you can stuff loads of little blue connectors in the grenade launcher for a grenade-like affect.To make original design go to www.instructables.com/id/Knex-sniper-M40A3/
Also you could add some sort of shock absorber so stop ram from flying out the end and I might post my assassins creed hidden blade soon which is awesome.So check out my pics below.