I have had a very standard m4 cqb aeg from tippman. I live in California so it's usually not that cold here. I having trouble deciding between a gbb or co2 first of all? The gun I have been saving up for is the hk416 full metal. I have about 600 dollars saved up just can't make up mind. I don't know if there is any co2 hk416 full metal blowback. The only one I came across but don't have alot info on is SR416 D10 Airsoft Co2. I know that Tokyo Marui has aeg hk416 delta and DEVGRU. I know that Umarex / VFC HK416 GBB Gen 2 GBBR and Umarex (VFC) HK416 A5 GBBR are good guns also. Please help thank you for all your input I know you probably answered this many times but thank you for taking the time.