Does any one have a pic of this mag tube installed on a supernova tactical, the company says it wont extend past the end of the barrel on a supernova tactical with the 18.5" barrel. The 2 shot extension tube from GG&G measures 6 3/8" long per there website, I measured my gun today from the front of the barrel ring to the end of the barrel and it measured 6 1/8" so it will go past the end of the barrel, just looking for a pic of one installed or any info from someone that has one. Thanks