Group B

Hello all, I'm interested in buying a new M2 Tactical w/pistol grip stock, but I'm looking to have 8-shot capacity. I've seen several 3-shot magazine tube extensions for the M2, which would extend the capacity to 8 shots, but they indicate that the barrel must be at least 20". I can't find any information about an M2 Tactical available with a barrel longer than 18.5", nor can I find any replacement Tactical barrels available. Any/all assistance is greatly appreciated! B