You'll find that unlike paintball, you can't tune airsoft guns, even gas ones. The only way to tune AEGs is by swapping springs, which requires a complete teardown of the gun and its mechbox. Pistols can usually have minor velocity changes made with replacing some internals, but the velocity changes are minimal.
And as long as you're 18, you can play. You just can't get access to the all-black guns and retailers in the private sections of this site. And many games will have age-verifiers in attendance, so it's easy to get verified.
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