Or you can save time and money, set your gun to CQB safe FPS and use it outdoors as is. You don't really need the extra power outdoor, it will not increase range significantly and for brush penetration you can just use heavier BBs. I've been playing for years with a Cyma AK set at 330 fps (with 0.20g BBs), and with .28g BBs it has a range of 200 feet and shoots through brush just fine.
Keep quiet. Sound travels faster than BBs.
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