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shakman
05-29-2005, 05:56 PM
I just finished upgrading my CA M15A4 with a new Guarder hopup bucking, Area 1000 piston, Promethius polycarb piston head, and Systema spring guide. The internal upgrade seems to be working OK, but now my AEG has started to double/triple feed during semi-auto firing. :cussing:

At first, I thought it was the bucking, so I switched back to the original factory bucking. No change. I'm pretty sure it's a hopup problem, but I'm not sure where to proceed from here.

This problem was NOT happening at all before I installed the new parts, so it's obviously something I did. I just don't know what.

Any ideas? :sad:

AustinWolv
05-29-2005, 06:35 PM
It fires correctly on full-auto?

Couple things to check:
-Ensure hopup bucking is lubed very well prior to installing on barrel, and also the hopup chamber where the bucking inserts. It is possible that the bucking is stretched and thus deformed after being installed.
-Ensure nozzle is attached to the tappet plate correctly.

shakman
05-29-2005, 07:03 PM
It fires correctly on full-auto?
As best I can tell, yes, but that seems kinda odd to me.

I thought I put enough lube gel on both the bucking and into the hopup chamber itself, but I'll redo both those steps just to make sure.

Would there be any internal mechbox reason (other than the nozzle/tappet plate lineup) that would cause this type of problem?

Agrovale
05-29-2005, 10:00 PM
Are you sure the little spring on the front of the hop up mechanism that pushes the hop up assembly up against the mechbox is still there?

AustinWolv
05-30-2005, 08:48 AM
I thought I put enough lube gel on both the bucking and into the hopup chamber itself Hmmm, those areas like silicone oil better. 10-20W, available at local R/C hobby stores, is good. But I presume none of that got into where the BBs will be traveling, correct?

Agro's spring suggestion is a good one also. That little sucker likes to hide.

Ralph Wiggum
05-30-2005, 09:55 AM
shakman9999, I think you and I may have the same problem. I have found that the hop-up is too tight and the bucking gets pushed over the end of the barrel the farther you insert it into the hop-up itself. I have tried several different buckings and it's always the same.

I ordered a new hop-up and it should be here later this week. I'll let you know what the results are.

shakman
05-30-2005, 08:16 PM
Well, I re-lubed the bucking and the hopup chamber and made sure the spring on the front of the hopup is there. No change. It's still puking all over itself :vomit:

Full auto fire is doing the same thing. In fact, now if I shoot full auto, then switch to semi, the first "shot" is 4-5 bb's at once! I suspect it was not feeding right in full-auto earlier, but I didn't actually see it. :cussing:


I ordered a new hop-up and it should be here later this week. I'll let you know what the results are.
Yeah, I'm curious to see your results. What did you order?

Thanks to all who responded. I'll keep dinking with it. If y'all have any other suggestions, or recommendations, feel free to post/PM me.

shakman

AustinWolv
05-30-2005, 08:38 PM
the first "shot" is 4-5 bb's at once! Sounds like something is blocking the path, be it the hopup bucking, too much hopup dialed on, some sort of injection-molding flash in the chamber, etc.

One thing to try to see if it is the hopup bucking: Take the inner barrel out with the hopup chamber still attached. Stick a BB in the chamber and cover the feed tube hole with your finger. With the hopup dialed all the way off, you should be able to blow the BB through the barrel. If not, that sucker is too tight.

shakman
05-30-2005, 09:15 PM
Hmmm...I'm beginning to suspect that there is some sort of alignment issue inside the gearbox that's causing my problems.

First, I need to confirm how the firing sequence works. When the gun is sitting "idle", the nozzle is resting in the hopup chamber and blocks the BB's path from the magazine into the chamber. When the trigger is pulled, the nozzle retracts to allow a single BB to pass. The nozzle then snaps forward forcing the BB into the barrel to the hopup nub. The piston slams home and the BB is then fired. Is this correct?

If so, then I suspect there is some sort of timing or gear alignment problem in the mechbox that is causing the double feeding.

Is there a "proper way" to re-insert the gears such that the firing sequence will be correct?

I know I'm grasping at straws here, but I fail to see how my AEG will work just fine before an upgrade, and fail so terribly afterwards. Since I'm new inside the mechbox, it's entirely possible I just screwed something up when I was putting it back together.

Am I on the right track? :sad:

AustinWolv
05-30-2005, 10:19 PM
Gear timing is basically a myth. Gears are not "smart"; they merely rotate. The gears will "time" themselves since they rotate such that the piston will be released early once the last tooth on the sector gear passes. Since there are no more teeth to engage the piston, it will shoot forward.....basically, a short stroke. When that happens, the piston will be all the way forward for the sector gear to come around again and pick it up properly, thus resulting in the proper full strokes thereafter.

Check that your tappet plate isn't broken. Then check that the nozzle is connected properly to the tappet plate.....the tappet rib should be sitting in the nozzle groove.

Ralph Wiggum
06-01-2005, 03:25 PM
Ok shakman9999, I installed the G&P hop-up and that seems to have fixed the double feed problem with my STAR low-caps and CA high-cap, but my TM mags still double feed every time during semi-auto fire. Do the TM mags have a stronger spring?

shakman
06-01-2005, 04:18 PM
Ok shakman9999, I installed the G&P hop-up and that seems to have fixed the double feed problem with my STAR low-caps and CA high-cap, but my TM mags still double feed every time during semi-auto fire. Do the TM mags have a stronger spring?

Good deal!

I'm not sure if the TM mags have a stringer spring. I have 3 CA std mags, 1 CA hicap, and 1 ICS hicap. I get the same behavior from all my mags.

I've got one more thing that I'm gonna try this weekend before I start swapping out more parts. I'll keep ya posted...

AustinWolv
06-01-2005, 04:21 PM
Ralph, I missed it.....TM hi-caps or standards?

I know the hi-caps have pretty strong coil springs as they'll feed nearly the entire mag once fully wound, which is not the same performance I've gotten from other M16 hi-caps.

The standards definitely have a strong spring, but not that of a TM hi-cap.

Ralph Wiggum
06-01-2005, 05:03 PM
'Wolv, these are TM high-caps and they are fairly new. Do I need to get a stronger/tighter hop-up bucking?

EDIT:

Here are my not so scientific results:

STAR Low-Cap = No double feeds
CA High-Cap = No double feeds
ICS High-Cap = No double feeds
TM High-Cap (6 months old) = No double feeds
TM High-Cap (6 weeks old) = Double feeds almost every time

The age of those TM high-caps are an estimate, but thatís pretty close.

AustinWolv
06-01-2005, 05:32 PM
What bucking do you have installed? The Guarder one? That should be sufficient.

If the bucking is installed correctly and isn't damaged, it shouldn't be a problem. If it is the Guarder bucking that I think you have, I doubt you have enough rounds through the gun to wear out the bucking.

Take the little spring off the front of the hopup chamber and pull on it slightly to stretch it out. Those can compress over time, allowing double feeds. If the problem continues, you may need to replace that spring or try shimming it with a spacer, so that rearward-pressure is maintained on the chamber.

Another caveat that I've only seen happen in limited situations: The nozzle isn't aligned well with the hopup chamber and actually can catch on the inside walls of the hopup chamber. The friction from that interaction actually causes the nozzle to travel like it should, causing double-feeds, loss of air seal, and possibly stripped pistons. Not necessarily the case for you, Ralph, but relevant to similar symptoms that others may encounter.

Or maybe those new TM mags just need to settle in a bit for you. ;)

Ralph Wiggum
06-01-2005, 05:39 PM
ACK! I messed up that Guarder bucking while cleaning it a while back and the only extra I had was a "used" Classic Army" bucking. I tried a Systema bucking, but I messed that one up too. Hmmm...Maybe I need to purchase a new Guarder bucking and let someone else put it on? :confused:

AustinWolv
06-01-2005, 05:46 PM
Ralph, ahhhh.....get rid of that CA tire rubber chunk they call a bucking. Systema or Guarder, whichever you choose will do.

shakman
06-04-2005, 12:48 PM
I just tore open the mechbox again. The nozzle is properly seated into the tappet plate. Nothing appears to be broken.

I did find one problem. The anti-reversal spring somehow got pinched next to the latch. Basically, the latch was stuck open and allowing the gears to reverse once the motor stopped. I did fix that, but I still have the feeding problem.

I noticed something odd. I was watching the nozzle while I pulled the trigger by looking into the chamber. After the piston cycles, the nozzle is pulled back and held there. Is this normal? It seems to me that is how the additional BB's are getting into the chamber.

If it's not normal, how do I fix it? Or does this all come back to a f'd up bucking/hopup?

This is so frustrating...HELP!!!

AustinWolv
06-04-2005, 02:22 PM
After the piston cycles, the nozzle is pulled back and held there. Is this normal? Yes, it can happen that way. If you look at the sector gear, the nub is a bit before the first sector gear tooth that engages the piston. This means the tappet plate is contacted first, pulling the tappet plate and nozzle back just before the sector gear tooth starts pulling the piston back. So even shooting on semi, it is possible for the gears to come all the way around with the nub hitting the tappet plate, but the piston not being engaged yet.

Well, if your hopup bucking checks out ok, maybe there is something going on with your tappet plate or nozzle. Such as the tappet plate being out of spec and getting pulled back too far or the nozzle being a touch too short, allowing an extra BB to enter the chamber.

That being said, those wouldn't explain the 4-5 BB shots you experienced before.

Are you ever getting misfires? Or does the gun fire every time, but just 2 BBs come out?

shakman
06-04-2005, 04:07 PM
Are you ever getting misfires? Or does the gun fire every time, but just 2 BBs come out?
Nope, it hasn't failed to fire ever. it's just double-feeding on semi.

I"m not convinced the bucking checks out. I may just go ahead and get a couple more just to make sure it didn't get stretched out. Since these are pretty cheap, if this'll work, I'll be happy.

shakman
06-25-2005, 04:15 PM
**UPDATE**

I think I've finally fixed it.

I'm not sure exactly what I did differently this time, but the double feeding has all but stopped. I still occassionally get a double feed on semi, but it feeds properly with all my mags on full-auto.

The only thing I may have done differently this time is that I didn't lube up the entire gear face when I re-inserted the gears. I only applied grease to the gear pin and the bushings. I have no idea why that would decrease the double-feeds, but if that's what it takes, then so be it.

I think I will still go ahead and replace the bucking and maybe that'll fix it up for good.

Whew! What a headache!

CALI
06-27-2005, 03:16 PM
Correct me if I'm wrong, but I don't think grease/lube is the reason why your AEG doesn't normally feed. Lubricant infact is good for reducing friction (metal to metal especially), helps prevent rust and corrosion, reduces wear etc. Pretty much its "good stuff" in extending the life of your gears/mechbox.

CALI

Falcon
06-27-2005, 10:43 PM
Semi auto double feeds are typically caused by the anti reversal latch catching the bevel gear too late. There are only two detents for the anti-reversal latch on the bevel gear, 180 degrees from each other. If the power to the motor is removed before the latch reaches the next detent, the spring tension causes the gears to roll backwards, and may cause the stud on the sector gear to engage and move the tappet/nozzle enough to allow an extra bb into the hop chamber.

I doubt it was the grease as much as where the anti reversal latch now engages on the bevel gear, which I suspect is a little different now than before it was opened for the grease.

shakman
06-28-2005, 09:59 AM
Falcon, I suspected it was some sort of gear issue, but I couldn't prove it.


If the power to the motor is removed before the latch reaches the next detent, the spring tension causes the gears to roll backwards, and may cause the stud on the sector gear to engage and move the tappet/nozzle enough to allow an extra bb into the hop chamber.
Any ideas on how to get around this? Is there a specific bevel gear orientation I should use during mechbox reassembly? I'm not having the double feed problem nearly as much as before, but it does still occur occasionally.

Thanx for everyones input! I really appreciate it.

AustinWolv
06-28-2005, 10:05 AM
Definitely not the grease.

On a related note, newer bevel gears, such as the ones that come with the Prometheus sets, have more notches.....5, I think. http://www.wgcshop.com/pcart/shopper.php?itm=PM-PT-TG_cat_Prometheus%20Parts

Systema has two: http://www.wgcshop.com/pcart/shopper.php?itm=SYS-ZS-02-10_cat_Systema%20Gear%20Sets

Guarder has three: http://www.wgcshop.com/pcart/shopper.php?itm=GD-PT-GE0201_cat_Guarder%20Parts%20for%20AEG

Phoenix looks to have eight:
http://www.wgcshop.com/pcart/shopper.php?itm=PH-PT-HPUPGS_srch_phoenix

Falcon
06-28-2005, 10:02 PM
Good info to know Wolv. It seems that gear manufacturers are catching on to the problem and offering subtle solutions.

Shakman9999, it's mostly trial and error. I've had the best luck by trying to set the anti reversal latch to where it catches the bevel gear right after the sector gear releases the tappet. Theoretically, this will keep the sector gear from actuating the tappet if it rolls backwards, because the latch will engage before the tappet is engaged.

Hope that helps. It sounds like you fixed it after the last time you opened the mechbox to apply the grease. Hopefully you won't have to go back in there for a long time.