u can get it after youve returned frm the spire. if あなた killed giles, it wnt be so easy. but if u helped giles get rid of ripper and his gang, u will notice a big change n brightwood farm. after あなた do 1 last mission for giles, he will reward あなた with the key to his cellar. thn just follow ur dog and fight ur way thru afew hollowmen and ur dog will lead u 2 where the weapon is buried.
あなた should do the quest Cold Comfort Farmer before going to the Spire. Once あなた return あなた should do the quest Blind Date. After finishing Blind Date, buy the farm house and 移動する in. Remove the key to the cellar from the closet on the 秒 floor and then rent the property out. The weapon will not appear if あなた are living there. 次 go into the cellar that あなた find in the 納屋 of the farm. Your dog will lead あなた to the Dig Spot where あなた will find the Enforcer rifle.