Egon_247 Posted May 22 Share Posted May 22 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 May 22 Supporters Share Posted May 22 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 May 22 Author Share Posted May 22 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 May 23 Author Share Posted May 23 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 May 23 Supporters Share Posted May 23 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 May 23 Author Share Posted May 23 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 May 24 Author Share Posted May 24 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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