WHOA slow the **** down man. First of ALL lower that puppy to 160psi.

Here is my tuning method that has gotten quite a few minis and axes shooting great:
1) pressure to 160psi
2)back cap ALL the way in
3) bring the cap out until you stop rising in fps (shoot like 5+ shots to confirm rise/drop in speed)
4) put the cap in just a little bit (not even 1/8th of a turn)
5)Adjust velocity through regulator (shoot 5+ shots to confirm rise/drop)

You may also need to buy a new gauge if you are going to 300 or over (on the v2 or v3 minis, not v1)