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Post by Stinger on Sept 25, 2014 20:06:53 GMT -5
I've been doing some work on a teammate's Echo 1 Platinum Edition M16 (OEM'd by VFC) to turn it into a long-range, high energy output, fast trigger-response build. To start, there were quite a few stock parts that would need to be replaced in order for the gun to withstand a higher energy output. I replaced the brittle polycarbonate piston (to an SHS 14.5) and tappet plate (to a Lonex V2 Enhanced), as well as the aluminum piston head (to a Lonex POM) and plastic cylinder head (to an SHS V2). I corrected the piston AoE, radiused the gearbox shell, corrected motor height, and perfectly shimmed it bevel-to-pinion. I also rewired it to Ultra Plugs (Deans). The stock cylinder was an aluminum type-0, and the stock spring was an M110. For now, we're keeping both of those, but the plan is to change that spring out to an M150. I know that we're going to need a better motor than the stock VFC, so we put in a Matrix 3000 Magnum Red (Torque). The plastic hop-up chamber was also replaced with a ProWin, and the stock barrel was replaced with a 705mm Miracle Barrel. Everything sounds fine and functions fine when cycling it. However, when I load it up and shoot it, I run into issues. I noticed that it's shooting about 300 FPS. It should be much higher. When investigating this, I found that the piston would stop its cycle almost fully compressed, but only when it was loaded and firing a round. Otherwise, with no BBs in it, it cycled normally and stopped at the normal position. I can replicate the issue by placing my finger over the air nozzle (blocking it) and firing in semi-auto. It stops in the same, almost fully compressed stop. I know this is bad to do because it leads to pre-engagement, so I haven't done it more than that. I'm wondering why this is happening. The BBs do come out of the barrel fine (besides being slow). There are no double-feeds or misfeeds, and it doesn't pre-engage unless it is firing BBs.
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zephurah
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Post by zephurah on Sept 25, 2014 20:17:04 GMT -5
That is extremely bizarre. The only thing I can think of is that the piston can not compress the air out of the nozzle enough, causing the piston to override the motors torque. Try changing out the O-Ring on the piston, or maybe lubricating the entire assembly more.
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Post by Stinger on Sept 25, 2014 20:25:35 GMT -5
That is extremely bizarre. The only thing I can think of is that the piston can not compress the air out of the nozzle enough, causing the piston to override the motors torque. Try changing out the O-Ring on the piston, or maybe lubricating the entire assembly more. If that were true, I would experience this issue while cycling the gun with the upper receiver off. I only get this issue when the gun is firing a BB. Otherwise, it doesn't happen.
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T6e9a
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Post by T6e9a on Sept 25, 2014 22:28:32 GMT -5
Things just to double check, would be to make sure the piston slides freely inside the GB shell, that there isn't resistance there. As well, if it has a ball bearing spring guide, make sure that the piston can retract over it without issue, and that the spring won't creep over the sides.
Also check to make sure that what you used to correct AOE didn't come loose by any chance, and start causing issues.
Essentiall open it back up and look for ANY sign, larger or microscopic, that could be causing said issue.
But on another note, after seeing that barrel length, I immediately thought: 'that gun is severely under volumed' Which might have something to do with the low FPS. And even with a bore up cylinder, it wouldn't be properly matched. (Might come close with a bore up extended V2 or V2.5 cylinder) Just some thoughts though.
I don't entirely understand the issue as it was described. But for reference, what bucking is in there?
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Post by Stinger on Sept 25, 2014 22:39:05 GMT -5
I have tried several buckings. The stock one was black in color. I have no idea who made it. It was too thin to seal properly with the ProWin, so now I've put in a MadBull Blue because that was the one out of all others which worked best. The inner barrel is actually 509mm in length, not 705mm. The owner told me he got a 705mm one, but I just measured it and he was incorrect. It is volumed correctly. I even tried shorter barrels and it made no difference in energy output.
The issue is that the piston ends its stroke with the spring almost fully compressed, but only when it is trying to propel a BB. Otherwise, with no BB chambered, it ends its stroke in the proper location. This is on semi-auto. It happens regardless of what combination hop-up chamber/bucking or inner barrel I use.
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T6e9a
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Post by T6e9a on Sept 25, 2014 23:12:19 GMT -5
So it essentially precocks for its next shot? Or am I off?
Quick test with the hop up/bucking: With everything in the hop up(barrel/bucking/nub) put a bb in the chamber(just free holding the barrel, easiest if pointing down) and then push it so it rolls out. How hard is it to push it through? Does the bb go through with a lot of force? Does it just fall through when you put it in? Possibility to look at and consider.
And just to be clear, this is with the M110? Have you tried any othe springs?
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Post by Stinger on Sept 25, 2014 23:31:42 GMT -5
So it essentially precocks for its next shot? Or am I off? Yup Quick test with the hop up/bucking: With everything in the hop up(barrel/bucking/nub) put a bb in the chamber(just free holding the barrel, easiest if pointing down) and then push it so it rolls out. How hard is it to push it through? Does the bb go through with a lot of force? Does it just fall through when you put it in? Possibility to look at and consider. I will test that later. And just to be clear, this is with the M110? Have you tried any othe springs? It is with the M110. I have not tried others, but I will.
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ctres
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Post by ctres on Sept 26, 2014 5:47:03 GMT -5
Wait, are you just saying that you are getting overspin? If so I doubt it has anything to do with the bb in the barrel. There are several ways to correct overspin if that is the issue, including an AB fet as well as a stronger spring.
If that's not the issue I'd say check for poor tolerances on the piston and tappet that could be causing it to hang up on the gearbox. I also think you should independently verify the spring rate by either testing the same spring in another gun or putting a different spring in the one you are working on.
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Post by Stinger on Sept 26, 2014 7:55:42 GMT -5
Wait, are you just saying that you are getting overspin? If so I doubt it has anything to do with the bb in the barrel. There are several ways to correct overspin if that is the issue, including an AB fet as well as a stronger spring. If that's not the issue I'd say check for poor tolerances on the piston and tappet that could be causing it to hang up on the gearbox. I also think you should independently verify the spring rate by either testing the same spring in another gun or putting a different spring in the one you are working on. If it were overspin, why would it only happen when the gun is firing a BB? The plan is to put in an M150, which is much stronger than the stock M110. No way I'm putting an AB fet in and burning up the motor Piston and tappet plate are both new and have no issues. Everything cycles perfectly fine with nothing loaded in the gun. As soon as I put a loaded magazine into it, the magazine starts stopping its cycle with the spring compressed. If I pull the magazine out, clear the breach, and dry-fire it, it cycles normally again.
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Post by natethegreat32 on Sept 26, 2014 21:30:30 GMT -5
To me, it sounds like pre engagement is a huge possibility. Look for ANY signs of pme. The stock vcf spring is extremely weak. I had a problem in a vfc where the shs 15 wouldn't go completely forward happily. Also, that setup is massively under volumed. Are you sure that it has a type 0 cylinder? all of the vfc's that I have worked on have type 1's. Which would make it even worse. Usually you want no more than 455mm. After that, you can see under voluming. If you haven't already, test it with a smaller barrel. My last thought is that there is a compression leak somewhere and your getting overspin. An m110 with 16:1 gears and a 16 tpa motor with extremely strong magnets, would have high regards to overspin.
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Post by Stinger on Sept 26, 2014 22:10:26 GMT -5
To me, it sounds like pre engagement is a huge possibility. Look for ANY signs of pme. The stock vcf spring is extremely weak. I had a problem in a vfc where the shs 15 wouldn't go completely forward happily. Also, that setup is massively under volumed. Are you sure that it has a type 0 cylinder? all of the vfc's that I have worked on have type 1's. Which would make it even worse. Usually you want no more than 455mm. After that, you can see under voluming. If you haven't already, test it with a smaller barrel. My last thought is that there is a compression leak somewhere and your getting overspin. An m110 with 16:1 gears and a 16 tpa motor with extremely strong magnets, would have high regards to overspin. It came with a Type-0 (no ports), and an M110 spring. It's not under-volumed. Trying a 363mm inner barrel in it had no effect. And again, if it were overspin shouldn't it happen even when it's not loaded?
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Post by natethegreat32 on Sept 26, 2014 22:22:42 GMT -5
The perfect barrel set for a type O cylinder is 455... Not 705 therefore being extremely extremely undervolumed Hmm this is wierd. So on semi with a mag in, you fire a shot and the piston precocks? Without a mag, it cycles normal?
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T6e9a
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Post by T6e9a on Sept 26, 2014 22:39:32 GMT -5
Nate, it also helps to read previous comments to see what has already been discussed...
Such as: OP measured the barrel to actually be 509mm. This would be found in a comment in response to one of my comments.
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Post by Stinger on Sept 26, 2014 23:33:05 GMT -5
So on semi with a mag in, you fire a shot and the piston precocks? Without a mag, it cycles normal? If the mag is loaded I get the issue. If the mag is unloaded, I do not. This is why I think it has something to do with the BBs.
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Post by natethegreat32 on Sept 27, 2014 13:56:45 GMT -5
So on semi with a mag in, you fire a shot and the piston precocks? Without a mag, it cycles normal? If the mag is loaded I get the issue. If the mag is unloaded, I do not. This is why I think it has something to do with the BBs. Sorry for the confusion there... If there is perfect compression (which i assume you have done for a "long range" rifle) there is even more added "friction" and once a bb comes into play, there is even more "friction". Maybe the piston is being slowed down by the compression and the bb, and possible a mag bb jam. which is causing the piston to jam up against something. You said the gb was cycling though? Not just a lock up? I wout try the gb with the stock piston, stock piston head and see if it still happens, maybe even the stock motor. Also, open up the gb and make sure that NOTHING was either assembled wrong and or nothing is broken. Overspin is expected for a 35 rps setup, but the fact it only does it with a bb is really wierd.
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