Avalon lock ups

[ProPain87]

Been having a few minor issues with my VFC Avalon Saber CQB which I’m planning on sorting out now I’ve nearly finished upgrading my sniper rifle. 

I’ve had the gun around 6 months and other than the issues I’m about to raise I’m pretty happy with it. 

It’s really consistent 280fps +/- 2fps with .25s and range and accuracy are pretty decent, the only thing I’ve done with it is convert to deans and clean the barrel as the accuracy wasn’t great out the box. 

Trigger response is not bad on 7.4 and really snappy on 11.1 and Rof is around 18rps on a 7.4 and iirc around 25 on a 11.1

The gun came with I think a m120 spring in it firing at about 390fps and another spring in the box which I’m sure is a m90 which is currently in the gun changed over by the shop when I brought it.

Some of the stock spec is,

16:1 gears

Ht motor (unsure of tpa)

Basic mosfet (same as krytac apparently)

Alu piston head

Qc gearbox 

Now that’s the overview of the gun, now for the issues I’m getting. 

With the current spring in I can’t use a 11.1, I get double shots on semi (overspin) and lock ups. With a 7.4 its fine with the occasional lock up when spamming the trigger and a quick flick onto auto and it’s sorted. Think it happened maybe 3 time on the last skirmish and thinking about it only happened when i swapped the battery at lunch (Morning battery nuprol 7.4 1450 30c afternoon battery vp 7.4 1300 25c)

I am planning on eventually getting a Titan and going all out with it to get the best trigger response I can but for now I’d like to keep things as simple as possible and hopefully not open the gearbox until I get the Titan. 

So for now Is there a simple way of stopping it locking up on semi, will a m100/105 spring and higher c battery’s solve my issues or am I going to have to tear it open. 

Apologies for the long winded post for such a simple question ?

 

[Iceni]

280 fps @.25g is about 0.9J you can run up to 1.12J

It sounds like an M90 spring.

If you have a Chrono or easy access to one I would use an M110 spring and cut it. If you don't get an M100. (Rocket airsoft black spring £5 each AK2M4)

0.9J 25rps double shooting. That's perfectly normal. 22 rps is normally the sweet spot between speed and no overspin. Chances are when you upgrade the spring it'll fall in line at about 22 rps.

Adding an AB mosfet will fix it, The titan comes with AB so you can wait for that upgrade.

16:1 gears aren't actually 16:1, there 17.28:1 and offer about an 8% speed increase over 18:1 gearsets. As such for a 22 rps build on 7.4v you are probably looking at a 25-30K motor. You should not need higher discharge batteries to power this, Generally, you will see 10-15 amps of draw, and the batteries you have are more than capable of that and will still be safe. Using higher C rated batteries will have no effect as your batteries are not a limiting factor, been able to supply  43.5 amps and 32.5 amps continuous and 87/65 amps burst.

The lockups on semi are all down to you. You sound to be spamming semi. If you control your fire I bet the problem vanishes. It's because you are not letting the gearbox fully reset between shots. And end up with the dolly floating over the sear. 

 

[ProPain87]

The lockups on semi are all down to you. You sound to be spamming semi. If you control your fire I bet the problem vanishes. It's because you are not letting the gearbox fully reset between shots. And end up with the dolly floating over the sear.

I definitely agree with this, I was hoping with a stronger spring, the piston would return faster in turn getting less lock ups when trigger spamming. 

0.9J 25rps double shooting. That's perfectly normal. 22 rps is normally the sweet spot between speed and no overspin. Chances are when you upgrade the spring it'll fall in line at about 22 rps.

So do you think I’ll be able to run it on 11.1 battery’s without overspin once the spring is upgraded?

im not too fussed about rof really, just a nice trigger response. So I think I’ll leave the motor as stock for the time being

 

[Iceni]

So do you think I’ll be able to run it on 11.1 battery’s without overspin once the spring is upgraded?

im not too fussed about rof really, just a nice trigger response. So I think I’ll leave the motor as stock for the time being

I think there is no harm in trying.

Something else that might work for you is shooting half a mag off on full auto. Lipo's have a distinct discharge curve and you can use it to your advantage when you run into situations like this where you are right on the edge of double shots.

You see the nice long flat part of the discharge curve, If you can get the gun to shoot normally at that part, It doesn't matter if it double shoots with a fresh battery... You can just run half a mag off before chrono to get it single shooting again. 

I have a gun that does this with 7.4 lipo's and a crazy motor. The trigger response is about as good as you will get without an AB mosfet. And because it doesn't have an AB mosfet you don't kill your motors. It is right on the limit for that second shot, so it acts like a pre-cocked trigger.

 

I definitely agree with this, I was hoping with a stronger spring, the piston would return faster in turn getting less lock ups when trigger spamming. 

It's not the piston causing the problem, You are not in the realm of PME. That starts to happen a little faster, 30ish rps.  The piston in your case is fully returning. It's the sear on the trigger and the trigger dolly causing the problem. You are spamming the trigger so fast that the dolly doesn't seat correctly. So the sear on the trigger and dolly end up out of alignment with no possible way to interact. Switching to auto will kick the dolly back down.

PME is a catastrophic failure for most gearboxes. You eat the piston teeth and gears.. The gearbox doesn't lock and free itself... It eats itself and needs rebuilding with new parts.

 

[ProPain87]

Appreciate the advice, I’ll start with changing the spring for now and give a 11.1 a go to see what happens and I’ll report back. Even if I can’t use the 11.1 the FPS increase will be welcomed

Sounds like Ill just have to calm down on the trigger until I get a Titan ?