TAC-41 Hopup unit, “GBB” type   TAC-41 optional hopup unit, for “GBB” inner barrel & “GBB” hopup rubber. Parts included:   – T41-0226 hopup body “GBB” (aviation grade CNC construction) – T41-0227 hopup rubber socket (aviation grade CNC construction) – T41-0228 barrel clip (SS304 laser cut) – T41-0202 hopup wheel – T41-0203 concave nub – T41-0224 feeder – T41-0225 feeder spring guide – T41-1008 spring – HOP-316001 60° flat hopup rubber, “GBB” type – M5X6 ISO7380-2 screw – M3X6 ISO7462 screws (x3) – M4X8 DIN7991 screw – M4X5 ISO4027 screws (x2) – oring 8×2 (x1) – 4 mm ball plunger   Use of optional cylinder head, not included, is compulsory, SBA-CYL-33 This TDC (Top Dead Center) hop up has 0.75 mm nub travel amplitude, divided in 50 positions (15 µm per clic). It includes a feeding system to avoid double feed, a 60° flat “GBB” hopup rubber (SBA-HOP-41), and it is compatible with “GBB” hopup rubbers and “GBB” inner barrels. To accommodate different brands of barrel, it can be assembled either with the barrel clip, or with the 3 M3X6 screws.   Because of a different inner barrel position inside the hopup, this unit requires inner barrels at least 3 mm shorter than the “AEG” hopup unit equipped with the same outer barrel to avoid inner barrel sitting out of the outer barrel.   – “510” outer barrel requires a 507 mm GBB inner barrel – “420” outer barrel requires a 417 mm GBB inner barrel – “330” outer barrel requires a 327 mm GBB inner barrel   This hopup unit is compatible with the advance hopup kit (SBA-HOP-34)