Hi i'm 19, Is there any way I can rent a gun and use the range? I want to get some knowledge and experience in for a G class security license.

You need a group of 2 to rent firearms. The waiver you sign says 18 and up can rent long arms but that might have changed with Rick Scott's bill last year.

You must have a ID and a 21 year old adult with you

You would have to take someone 21 or older to fire rental pistols. A friend or parent would suffice and meet the need... You can rent long guns at 19.