Egon_247 Posted Thursday at 14:44 Share Posted Thursday at 14:44 So.... Having been given a 20+ year old TM m4a1 by someone, Im trying to get it up and running again. Gearbox done, gears, grease n shimming, new piston n m100 spring. All happily doing their thing. Only issue now is that it had a 2 piece hop unit. But alas, one bit was missing along with the barrel. 😕 So I've attacked it with a Dremel and made one fit (an old g&g I had kicking about), bought a barrel too There's no space in front of it for the spring. Upon test firing just now it doesn't feed at all well (1 in 3 shots) but when it does it's up to 0.8j. I get the feeling that the g&g hop unit is crap, it's not a rotary one, so I've ordered a zci one to go in it. Is the spring an absolute necessity? I've heard tales of o rings being used to shim it back to the V2 gearbox. The mag lines up ok but my concern is that if I shim the hop back to the gearbox, the mag won't line up. Any thoughts? Link to comment Share on other sites More sharing options...
Supporters Lozart Posted Thursday at 14:58 Supporters Share Posted Thursday at 14:58 The spring is there to make sure the nozzle seats against the hop rubber properly, that's all. You can definitely use O-rings but they're less forgiving of any magazine misalignment. Egon_247 1 Link to comment Share on other sites More sharing options...
Egon_247 Posted Thursday at 18:15 Author Share Posted Thursday at 18:15 3 hours ago, Lozart said: The spring is there to make sure the nozzle seats against the hop rubber properly, that's all. You can definitely use O-rings but they're less forgiving of any magazine misalignment. Cheers matey. This is the first time I've done a hop unit that wasn't a straight swap. It's sat against the gearbox pretty solid but I'll give the o rings a shot 😁👍 Link to comment Share on other sites More sharing options...
Egon_247 Posted Friday at 17:48 Author Share Posted Friday at 17:48 Aha...eureka moment. Looked into the feed tube and the nozzle isn't clearing the tube enough to allow it to feed. Looks like it might be time for a sector delay thingy. Might pull it back far enough to work. 😁😂 Rogerborg 1 Link to comment Share on other sites More sharing options...
Supporters Rogerborg Posted Friday at 17:55 Supporters Share Posted Friday at 17:55 5 minutes ago, Egon_247 said: Aha...eureka moment. Looked into the feed tube and the nozzle isn't clearing the tube enough to allow it to feed. Looks like it might be time for a sector delay thingy. Might pull it back far enough to work. 😁😂 Ah, that makes sense, especially if the tappet plate is a bit worn. Thanks for the followup, it's good to hear solutions to the questions. Link to comment Share on other sites More sharing options...
Egon_247 Posted Friday at 19:15 Author Share Posted Friday at 19:15 1 hour ago, Rogerborg said: Ah, that makes sense, especially if the tappet plate is a bit worn. Thanks for the followup, it's good to hear solutions to the questions. I just tried a shorter nozzle and it's feeding, just at 0.2j. 😁😱😂 Looks like I need the original nozzle to come back a bit further to clear the feed tube. I wouldn't mind so much but the front wired M4 is a pig of a fiddle to do. 🤬😱😂 Actually, thinking about it, I can't do that cos the tappet plate is held against the cylinder head isn't it? Oh well. Hop unit change. Grrr. Link to comment Share on other sites More sharing options...
Egon_247 Posted Saturday at 08:52 Author Share Posted Saturday at 08:52 Maybe, just maybe, the V3 tappet plate in the V2 gearbox that was installed by the previous owner wasn't the smartest move..... I dunno. Some people....😳🧐 Herrgh and Rogerborg 2 Link to comment Share on other sites More sharing options...
Egon_247 Posted Sunday at 15:55 Author Share Posted Sunday at 15:55 Just a matter of nozzle length now I think. It's still a bit meh. Rogerborg 1 Link to comment Share on other sites More sharing options...
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