Beware of too many (mismatched) aftermarket AEG parts

[CDN_Stalker]

I've been working on a new guy's CA M15 for at least 6 hours now (8 or 9 if you include the hours I worked on it after I got it) and it's pissing me off. max velocity I've gotten out of it has been 312fps with a Madbull 110 spring (same as in my MP5SD, which is a 400fps gun), and the lowest is 49fps.

Piston: Some smoked semitranslucent polycarb piston, initially found it was binding ont he mechbox rails.

Pistonhead: Some alumimum ported head, seems the groove in it is to wide and air from the ports escapes behind the O-Ring.

Spring: Came with a Prometheus 110 spring.

Tappet Plate: Some yellow plastic one.

Cylinder head: Some purple aluminum one with the tapering inside like it's meant for a silent pistonhead.

Nozzle: Some brass tapered one, airseal type.

Cylinder: Chromed steel with ribs (for her pleasure?)

Hop up rubber and unit: Brand new Guarder with an odd clear rubber, which has breech lips longer than most rubbers I've deal with, explains the serious plugging, feeding 1 BB out of every 8-10 shots. No amount of oil helped.

So, I've swapped out and tried parts I have sitting around, nozzle, various hop up rubbers, various piston heads (including a Systema silent one) with different O-rings, a Modify ported head, a Deep fire ported head, even a stock TM head. Nothing does anything any good, either gets worse or stays the same. Just tried it now with the owners parts in it, and a Prometheus 120 spring (put out 435fps in my MP5) and I'm getting 150-165fps out of it. Am really at a loss right now, going to have to contact the owner and see where he wants to go. Thought maybe I'd pull out some of the stock TM parts in my MP5SD (is shooting to close to 400fps for my tastes) and just trade him them, give him at least a shooting and reliable gun.

Now I can see why the owner sold it, too many mismatched parts, too many problems. Is obviously an airleak somewhere, and I thing the best thing to replace would be the cylinder, since it seems the pistons aren't getting enough initial compression to inflat the O-ring properly, but I only have an MP5K cylinder to try currently, but that'll cause suckback, so I don't see it as a good test part. Also wrapped the cylinder head's O-ring with teflon tape since I found no piston head put out compression even with no nozzle on it. Got a couple pistonheads to give varying amounts of compression, some very good compression, but never when actually shooting the gun.

Sigh!

[mateba]

I'd like to help but I might not be right. I'm just making suggestions of what I would do and hopefully prevent you from buying new parts. Start from the source and work out ward to the barrel this way you know where you have been.
Compression unit
Teflon tape the cylinder head. I like to wrap mine so that once in place the tape is half in the cylinder and half out. Then fold the protruding half back over the cylinder to sandwich the tape between the cylinder and head.
Check your o-ring on your piston. I like #14 o-ring from hardware stores for normal non-boreup piston heads. But if the metal piston head has a wide gap you might have to take it with you. You might want to try a new air nozzle if you find that it is the weak link. Deep fire air nozzles fit particularly tight and their cylinder heads may be a slightly different due to this.

Parts (possible)
Deep Fire cylinder head, http://www.deepfireairsoft.com/airsoft-piston.html
Cylinder, there are many companies that use ribs including Deep Fire. Could this be a bore-up?
Piston, sounds like Modify or Echo1 pistons, http://www.modify.com.tw/products_e.html
Tappet plate, Classic Army, http://www.classicarmy.com/search.jsp

I hope this helps, it sounds like it could be about anything. My best advice is to start at one end and just rule'em out so you don't go crazy.

good luck

[CDN_Stalker]

Just an update, just a discovery and not (yet) a huge hurrah.

I was checking out the tappet plate (looks like it's a stock CA tappet juging by the type of plastic........ don't recall previously seeing yellow ones in CA guns I've worked on in the past) after checking the piston movement (no spring, mechbox screwed together) and I'm getting pretty decent compression when ramming the piston forward, and while I've had problems in the past with certain nozzle/hop up units, I decided I didn't pay much attention to the tappet. I did notice the nozzle was a bit wobbly, but also on close inspection, saw that it was very slightly bent backwards (more like a very slight lean). And, when I pulled out a new V2 tappet, saw the 'rail' that the nozzle seats in, the new one had the rail about 1mm farther forward than the yellow one. Yellow one was also pretty worn. If this is the case, then it look like the nozzle isn't being allowed to go farward as much as it should with this shitty yellow tappet, so I'm going to try it out after I find out where the new tappet is binding inside the mechbox.

Stay tuned, I think I might have zero'd in on the problem.

[CDN_Stalker]

Originally Posted by mateba

I'd like to help but I might not be right. I'm just making suggestions of what I would do and hopefully prevent you from buying new parts. Start from the source and work out ward to the barrel this way you know where you have been.
Compression unit
Teflon tape the cylinder head. I like to wrap mine so that once in place the tape is half in the cylinder and half out. Then fold the protruding half back over the cylinder to sandwich the tape between the cylinder and head.
Check your o-ring on your piston. I like #14 o-ring from hardware stores for normal non-boreup piston heads. But if the metal piston head has a wide gap you might have to take it with you. You might want to try a new air nozzle if you find that it is the weak link. Deep fire air nozzles fit particularly tight and their cylinder heads may be a slightly different due to this.

Parts (possible)
Deep Fire cylinder head, http://www.deepfireairsoft.com/airsoft-piston.html
Cylinder, there are many companies that use ribs including Deep Fire. Could this be a bore-up?
Piston, sounds like Modify or Echo1 pistons, http://www.modify.com.tw/products_e.html
Tappet plate, Classic Army, http://www.classicarmy.com/search.jsp

I hope this helps, it sounds like it could be about anything. My best advice is to start at one end and just rule'em out so you don't go crazy.

good luck

Thanks for the advice, but I think I'm well beyond having advice given in cases like this. Troubleshooting is second nature to me (do it enough at work) and I've traced the problem down even further than previously (have had my share of stubborn guns, this one is definitely a pain, want it off my bench so I can work on a G3 SG1 for the same client.) I've seen some very odd things over the past few years of my being a gun tech (it's literally a full time job now one I get home from my instrumentation technician job during the day, since every weekend and evening since mid-December I've had gun work to do. (I must have made at least $600 so far, and this is the OFF SEASON!!!)

I appreciate the interest you took and the time to type, but this thread is primarily a warning to people who think the more upgraded parts, the more reliable the gun will be. From all I've seen, the opposite is true 90% of the time.

Regarding your links, ya, that's the cylinder head (he who installed it didn't even put a spot of grease on the nozzle though), didn't bother digging through the Modify or CA links though. Gonna head back to my bench now and give the gun a try after the tappet installation and see if I'm any closer.

[mateba]

should have guessed.

BTW, the mixed parts aren't even the issue if its the tappet plate. That would be stock in a CA and if you have worn parts you have worn parts.

[CDN_Stalker]

Sorry, thought about my words used above, what I meant is that the stage of troubleshooting right now is beyond my experience so far, and well beyond even adanced advice. When yo uget down to checking the nozzle/tappet relationship, you have tossed te fine toothed comb and are into microscope areas. Lol, sucks this new tappet needs a lot of filing to make it not bind up in the mechbox grooves. Still poking at it.

[Crunchmeister]

Yeah, parts don't all fit like they're supposed to. I've been discovering that myself as I'm starting to delv into the upgrade thing myself.

I upgraded my CA M15 rifle yesterday. I installed a Systema red polycarbonate piston, Systema spring guide, and a Systema silent piston head / cylinder head set. Also threw in a Prometheus MS110SP spring. BTW, my stock CA tappet plate is yellow as well. Looks like I'll be having to replace that as well soon. It's showing some wear on its edge where the cam from the sector gear connects with it. Ugh... more money to spend on this gun. lol

Now, initially, there was a fit problem. The stock CA cylinder seems oversized. I couldn't get ANY compression with the Systems piston assembly. When I blocked the nozzle with my finger and compressed the cylinder, all the air would leak out from around the piston head o-ring and out the back of the cylinder. I had to swap the Systema o-ring with the stock CA one in order to get a positive seal. It does work great with the CA o-ring though. I get what appears to be excellent compression now.

Now I test fired the gun, and it does appear to hit quite a bit harder than it did while stock. I'll be receiving my chrony on Monday or Tuesday, so will be able to give some numbers then. But I was able to get results similar to those with my JG MP5. I can easily punch through the bottom centre and almost through the inner edge of a coke can. I'll post some numbers in Kokanee's Prometheus spring thread when I get my chrony.

Good luck getting the gun working.

[damage]

Originally Posted by CDN_Stalker

Hop up rubber and unit: Brand new Guarder with an odd clear rubber, which has breech lips longer than most rubbers I've deal with, explains the serious plugging, feeding 1 BB out of every 8-10 shots. No amount of oil helped.

Is this Guarder hop up unit one piece? If it is, this is one of the problem. I have a 5 pieces of this in my toolbox and swear never to use or install them in my upgrades/repairs. Last aeg that I worked one which have this hop up unit in it chronos 195fps with M100, spring guide and piston head and a 6.04mm tightbore then switched to one piece metal hop up and it solved the problem now the gun shoots 320fps.

[wKnight]

I can't agree more with not using a mishmash of brands to do upgrades/repairs. I have found that even parts that say they are 100% compatible can turn out to be off by just a bit. If you add enough of these off parts together it will likely lead to trouble sooner or later. I'm a big fan of the pre-built mechbox's for upgrading since you get exactly what you want and everything is designed to work together.

[MadMax]

Well, that's what you get when you get half a dozen hobbyiests copy a product with non NIST traceable measuring equipment. Dimensional tolerance salad.

Imagine sending a production car to six different car parts manufacturers and getting them to make one out of six components. They each only get one complete car to duplicate their parts from and they're not allowed to talk to each other and share their measurements to develop any knowledge of manufacturing tolerances that their base machine is built to.

Hide all the stuff in a dump and it's basically Junk Yard Wars in a dump with really excellent stuff that seems purpose built but has to be cobbled together filed down and/or filled up to come to some semblance of working fitment.

[CDN_Stalker]

Good to know the plastic Guarder hop up unit is possibly part of the problem. I linked this thread to the owner, so he can check up on it.

Still having a huge problem with the cylinder head/nozzle/tappet plate (the new one) it jams up when pressed back and takes some good tugging to get it to come loose. Tappet in fine on it's own and with the cylinder head but no nozzle. Add the nozzle in and it jams back. Undo the top front corner screw from the mechbox and it frees it up. Getting frustrating enough that I gave up for the night, already spent a good four to five hours on the gun today with no improvements. Even a stock V2 nozzle with no internal airseal O-ring is jamming up the exact same way.

[ILLusion]

The piston could also be Angel brand
The tappet plate and cylinder sounds like the stock Classic Army ones.

I recently worked on a Classic Army SR-25 that was exhibiting the exact same problems you were having. I attributed all issues to really shitty stock Classic Army parts.

The cylinder compression test concluded that... well... there was no compression because air was just firing everywhere. First thing I did was swapped the piston head and cylinder head to a Systema silent head set and the gun went from shooting anywhere from 80-180fps and after the silent head set was installed, it was shooting about 330fps consistently.

But the power was still pretty low, considering the spring shot 425fps in my P90 test platform.

I did the compression test again and checking for air leaks and realized: Classic Army air nozzles are the WORST designed air nozzles in the entire industry. I don't know who the knuckle head engineer is who designed them, but they have slots cut in to the side of the air seal nozzle, so guess where the air goes when the gearbox fires? That's right... NOT out the front and down the barrel. It fires all around the hop up chamber and out the magwell.

The shitty thing for my client was that his SR-25 pretty much has impossible to find and unique parts. The only "proper" air seal nozzle you can get for the SR-25 is the G&P one, and unfortunately, is only available with their gearbox kit. If all you need from that kit is the air seal nozzle, that's a $250+ air seal nozzle...

Anyways, the client just wanted the gun to work and was willing to pay for the air seal nozzle. Once it was replaced, the gun was shooting 380-390fps at a somewhat okay consistency. Not as efficient as I'd hoped, but considering the amount of time put in to the gun just to get it to where it was, my opinion on Classic Army guns remains the same - GARBAGE.

Whoever designed some of their parts deserves to get full auto'ed with a hi-cap. Not from a Classic Army gun, of course... because they wouldn't be able to put out enough power to teach him a lesson. har har harrrr

Originally Posted by Crunchmeister

Yeah, parts don't all fit like they're supposed to. I've been discovering that myself as I'm starting to delv into the upgrade thing myself.

I upgraded my CA M15 rifle yesterday. I installed a Systema red polycarbonate piston, Systema spring guide, and a Systema silent piston head / cylinder head set. Also threw in a Prometheus MS110SP spring. BTW, my stock CA tappet plate is yellow as well. Looks like I'll be having to replace that as well soon. It's showing some wear on its edge where the cam from the sector gear connects with it. Ugh... more money to spend on this gun. lol

Now, initially, there was a fit problem. The stock CA cylinder seems oversized. I couldn't get ANY compression with the Systems piston assembly. When I blocked the nozzle with my finger and compressed the cylinder, all the air would leak out from around the piston head o-ring and out the back of the cylinder. I had to swap the Systema o-ring with the stock CA one in order to get a positive seal. It does work great with the CA o-ring though. I get what appears to be excellent compression now.

Now I test fired the gun, and it does appear to hit quite a bit harder than it did while stock. I'll be receiving my chrony on Monday or Tuesday, so will be able to give some numbers then. But I was able to get results similar to those with my JG MP5. I can easily punch through the bottom centre and almost through the inner edge of a coke can. I'll post some numbers in your Prometheus spring thread when I get my chrony.

Good luck getting the gun working.

Systema silent head sets require you to remove the o-ring and give it a good stretching out as you apply lube to it. It's part of the break-in process of the o-ring, but when done properly, the head sets provide a great seal - even in CA cylinders.

[CDN_Stalker]

Well, got the M15 shooting now, rather low with the Prometheus 110 spring, 300mm tightbore and bearing spring guide (all the same as in my MP5SD except I have a 330mm tightbore, is shooting 395-400fps), it is only pulling off 350fps with hop up off. I replaced the hop up unit (put in a Deep Fire metal unit, with TM parts in it), and sorted out the sticking tappet plate issue I'd been fighting with. Turns out the DeepFire tappets are higher on the nozzle end, about 2mm higher actually, where the notch to hold the nozzle in is, it was binding at the bottom, the CA mechbox is a bit thicker there. I put in my MP5's tappet and it works like a charm, and even the Deep Fire tappet is working well in my King Arms reinforced mechbox, so I guess we both got off lucky. So, if I can't sort out the low fps (350fps is fine, but he's hoping for 370-380fps), I'm putting in the Prometheus 120 I have kicking around.

[CDN_Stalker]

And now the gun is shooting 300fps with the 120 spring. Sigh, I'm taking a break from this damned gun for a bit, have half a dozen other guns in the que that need to be done by March 29th. Looks like I might be taking a couple days off work to......... work.

[damage]

Talk about CA M4's. I just finished overhauling a clients gun from new hop up seal nozzle, cylinder head, piston spring guide and spring and busted two new piston freaking gearbox still has some alignment issues so I put back the stock piston. I have yet to do the chrono.