My nitro Fire .177 is very accurate and hits hard (especially for $79.00) for about twenty rounds, then the accuracy falls off a cliff, 3 inches at twenty yards. I clean the barrel each time this poor accuracy returns and it goes back to being dead-on, less than an inch at 20 yards I have about 300 rounds through the gun and each time I clean the barrel, the swabs or patches come out solid black. Is this normal? Shouldn't the break-in be over after 300 shots? All stock screws and scope mounts tight and loctited in!