RT tuning Part II

[38super]

The short silver spring probably means they changed spring stock in the manufacturing. I am surprised the level 7 spring didn't work for you. It sounds like you have an understanding of the operation and a handle on the situation. If you need any further help, just post it up and we'll give you a hand.

Thanks; I want to understand it on a micro-level. I like to be self-sufficient with my gear and have no interest in switching platforms for flavour of the week. Yet there's a few things I'm still nibbling around the edges of, like why air that enters the gun and is then regulated can still cause RT effect if pressure is increased enough. But I'm still reading....

[athomas]

Yet there's a few things I'm still nibbling around the edges of, like why air that enters the gun and is then regulated can still cause RT effect if pressure is increased enough. But I'm still reading....

Air that enters the gun and passes through the on-off area is not regulated. It passes through the regulator, but only once it gets into the chamber area does it feed back through the regulator pin assembly and push on the regulator piston assembly to control the chamber pressure. The initial blast of air onto the top of the on-off pin is at full tank pressure once the front chamber is emptied and opens the regulator air flow. As the air chamber fills, it pushes on the regulator piston and allows the pin assembly sealing edge to get closer to the regulator seat oring which slowly restricts the air flow until it is closed off at the regulated value. That is the charge cycle.

When the front chamber is filled and you pull the trigger, the larger top area of the 0n-off pin is floating in pressurized air and has no bearing on the trigger pull. The regulated air is pushing against the smaller diameter of the on-off pin. So, when you pull the trigger, you are pulling against a smaller force of less diameter and less pressure. When the gun fires, the larger top area of the pin is pushed with a larger air pressure forcing the on-off pin out with much more force. Its the difference in force between the lower trigger pull force and the larger return force that causes the RT effect. That is why a higher tank pressure increases the RT effect. You are increasing the input force on the on-off pin during recharge while maintaining the same chamber pressure. This increases the differential forces and increases the RT effect.

[38super]

Air that enters the gun and passes through the on-off area is not regulated. It passes through the regulator, but only once it gets into the chamber area does it feed back through the regulator pin assembly and push on the regulator piston assembly to control the chamber pressure. The initial blast of air onto the top of the on-off pin is at full tank pressure once the front chamber is emptied and opens the regulator air flow. As the air chamber fills, it pushes on the regulator piston and allows the pin assembly sealing edge to get closer to the regulator seat oring which slowly restricts the air flow until it is closed off at the regulated value. That is the charge cycle.

When the front chamber is filled and you pull the trigger, the larger top area of the 0n-off pin is floating in pressurized air and has no bearing on the trigger pull. The regulated air is pushing against the smaller diameter of the on-off pin. So, when you pull the trigger, you are pulling against a smaller force of less diameter and less pressure. When the gun fires, the larger top area of the pin is pushed with a larger air pressure forcing the on-off pin out with much more force. Its the difference in force between the lower trigger pull force and the larger return force that causes the RT effect. That is why a higher tank pressure increases the RT effect. You are increasing the input force on the on-off pin during recharge while maintaining the same chamber pressure. This increases the differential forces and increases the RT effect.

Oohhhh...I think I get it now: it's a slam-fill, right? Incoming air has velocity and the higher the pressure the higher the velocity and thus, kinetic energy. The impact force of this on the top of the on/off pin is what causes the reactivity in that minuscule increment of dwell time that exists between inlet and reg seat closing/full pressure. Fascinating and ingenious!

So basically, what you have then in an X-valve is an extremely wide window of adjustable parameters that let the individual tune their equipment for their own preferred style of play.

But of course this begs the question; if the RT/X-valve has the this much range built into it, why does AGD discourage tuning them to maximum reactivity?

[athomas]

But of course this begs the question; if the RT/X-valve has the this much range built into it, why does AGD discourage tuning them to maximum reactivity?

Maximum reactivity is hard to control. The marker becomes dangerous in the hands of someone who can't.

Also, depending on the tuning, it can cause extra wear on the sear. This is usually when the shortened pin is used. It can cause the bolt to just barely catch the tip of the sear. This tiny area of contact rather than a larger contact area of a longer pin, results in sear wear.

[38super]

Maximum reactivity is hard to control. The marker becomes dangerous in the hands of someone who can't.

Also, depending on the tuning, it can cause extra wear on the sear. This is usually when the shortened pin is used. It can cause the bolt to just barely catch the tip of the sear. This tiny area of contact rather than a larger contact area of a longer pin, results in sear wear.

I see. I'll keep an eye on the sear for wear and adjust as/if necessary. As a quick follow-up, during this evening's indoor play I put 1200 rounds through the gun this evening. Final tune at the field (had to remove 1 ULT shim) and suddenly...perfect. Astounding, even. No chops either or barrel breaks either. I simply couldn't believe the performance, and judging from all the questions I was getting no one else could either.

It can RT between 2 and 5 shots easily, longer strings if needed and shoot singles as well, all on demand so it's pretty controllable. Absolutely stunning performance actually. Even the field ref couldn't believe it was a mechanical gun. While I wasn't necessarily looking to be able to RT, it sure helps even things up against the ramping guys, so I think I'll leave it that way for now.

Thanks to all who helped nudge in me the right directions. If you're in the GTA at some point feel free to look me up. I would be pleased to buy you a beer and maybe some lunch.

[athomas]

You shouldn't have to worry about sear wear. It is mostly directed towards level 7 setups and setups that have weaker bolt springs The level 10 keeps the forward force of the bolt low, so it hits the sear very lightly. Of course, once the bolt spring gets weak, this force increases and you could start to see wear. It is important to check the bolt spring for wear (ie; if it starts to get weak) and replace it when necessary. Bolt springs are a consumable item and need to be replaced periodically depending on how much the gun is used.

[38super]

You shouldn't have to worry about sear wear. It is mostly directed towards level 7 setups and setups that have weaker bolt springs The level 10 keeps the forward force of the bolt low, so it hits the sear very lightly. Of course, once the bolt spring gets weak, this force increases and you could start to see wear. It is important to check the bolt spring for wear (ie; if it starts to get weak) and replace it when necessary. Bolt springs are a consumable item and need to be replaced periodically depending on how much the gun is used.

Will do. From what I understand, once the spring is compressed down to the leading edge of the bolt it's time to replace, correct?

I suspect this will last quite a while though, since it'll get swapped out for the regular spring as soon as the nice weather returns and we can get back up to 280fps.

[athomas]

Will do. From what I understand, once the spring is compressed down to the leading edge of the bolt it's time to replace, correct?

That is only for the stock level 7 spring. A weakened long spring will still be longer than the bolt. It will just be weaker than when new. When this happens, the bolt won't reset properly. I had to replace my first level 10 bolt spring at about 35000 shots, if I remember correctly. At that time it was past its prime and was inconsistent in its operation.

[38super]

That is only for the stock level 7 spring. A weakened long spring will still be longer than the bolt. It will just be weaker than when new. When this happens, the bolt won't reset properly. I had to replace my first level 10 bolt spring at about 35000 shots, if I remember correctly. At that time it was past its prime and was inconsistent in its operation.

It's also probably worth noting that all springs are not necessarily the same. I've had recoil and magazine springs in my racing guns last seemingly forever, whereas I'll see the occasional one from the same manufacturer and of the same rating cack out in no time flat. Just something to keep an eye out for I guess.