if i sighted my gun in with a 295 grain bullet what would happen if i dropped to a lower grain?

A number of factors affect bullet performance, including weight, powder (amount and type), barrel twist, primer, barrel length, ballistic coefficient of the bullet, atmospheric conditions, etc.  While it is likely a lighter bullet will shoot higher than a heavier bullet, we recommend working with a qualified gunsmith or other firearms expert to know exactly how your gun would perform with a lighter bullet.