As lxss said ,you can use it but it is unlikely to find gold. On the weekend we had a bloke come out on our club outing with some type of tesoro(maybe diablo) It would show a bullet in your hand up to 2" /50mm but when we buried it in the mineralised ground you could hardly hear it just under the ground.His plan was to use the coin machine to find enough gold to buy a more powerfull rig. Most gold around .22 projectile size is usually down at least 150mm. Bury a bullet (lead only)and see how the 305 goes.A lot of the small gold being found is only 2" or 50mm.Get the smallest shotgun pellet you can find (around No. 7/10 shot) and flatten it and see if you can hear it. Hire machine costs around $50 a day,bpc charge $10 on our outing days only.