RT effect and LX tuning

[punkncat]

Is there some correlation between the two?

It has been a minute since I tuned an LX. My last mag I did it perhaps 2 times in the first year I owned it, and never had to again.

This mag I just picked up is INSANE reactive. It came with ULT, and would go full auto the second you tried to fire it. I don't have the shims yet, so I took an RT on/off I had left over and put in. Even with a preset screw in, this thing is going NUTS RT. It is pretty controllable, it does have to be sweet spotted to go full auto, but it is so easy to achieve. Every other mag I have owned required some mods to the on/off or an adjustable HPA to act like this.

On to the point. The LX is out of tune, has a bit too small a spacer I think. The marker is getting a hangup after it chuffs a ball, and have to pull the trigger, or wait about a second before it will reset and be ready to go again. While I was messing around with it, I put in a few powertube shims just to see if I could correct the "stick" problem checking each time I put them in for the bolt leak. I put in the five that I have making a total of seven, and never could get the stick to stop that way. But what I did notice is that the more shims I added in the LX, the less reactive the marker got, and of course more sensitive the bolt got to bouncing off paint, as it should.

Is this due to the shims moving the bolt slightly forward, and making the sear relationship just different enough to change the reactivity?

[fishmishin]

From what I understand is that the shims only affect where the bolt vents to prevent a chop. I don't think that the shims actually move the bolt forward, since you would have to make the powertube longer to move the bolt forward, just where it will vent at. It sounds like to me you just need to go to the next size carrier to prevent the bolt stick, which would be moving up a size. Also double check the o-ring in the carrier you are using now to make sure there is no damage to it. I would be interested in finding out though what resolves the problem, so I will subscribe to follow your progress.

[maniacmechanic]

marker is getting a hangup after it chuffs a ball, and have to pull the trigger, or wait about a second before it will reset and be ready to go again

How often does it do this ? A little stronger spring will help it reset

[athomas]

You are definately getting bolt stick if it takes a moment to reset after a chuff. That just means you need to use a larger carrier size.

If you are getting insane reactivity, your sear could be worn a bit on the tip where it catches the bolt.

[punkncat]

marker is getting a hangup after it chuffs a ball, and have to pull the trigger, or wait about a second before it will reset and be ready to go again

How often does it do this ? A little stronger spring will help it reset

Yeah, when I source some parts, I have to try the long spring. I have the standard gold spring in it now. I also think the carrier is a bit small and plan on going up one size and trying it.

Only does it on an actual chuff, missing the ball, due to using a revi. Does not happen at all while dry firing.

[athomas]

Yeah, when I source some parts, I have to try the long spring. I have the standard gold spring in it now. I also think the carrier is a bit small and plan on going up one size and trying it.

Only does it on an actual chuff, missing the ball, due to using a revi. Does not happen at all while dry firing.

When dry firing, you have full forward force of the chamber pressure on a lighter bolt spring. On the return, you have the full momentum of the bolt allowing a clean reset. On a chuff, the bolt is resetting from a position where the bolt spring is not fully compressed. If the friction of the carrier plus the force of the chamber pressure on the bolt stem is approximately equal to the force of the uncompressed bolt spring, then you have bolt stick. As the chamber pressure bleeds down, the bolt will reset. A stiffer bolt spring may help, but it may also cause a higher residual pressure, canceling out any advantage of the stiffer spring, especially since it will be uncompressed anyway. The friction will always remain constant for all situations, which is why it is always best to address the bolt stick by getting the carrier size and oring combination properly set rather than doing a bandaid fix of a stiffer bolt spring.

Essentially, you want to remove the friction from the equation as much as possible so that all movement is based on the differential force of the chamber pressure and the force of the bolt spring. Since one will always be greater than the other, you will always have movement and bolt stick will be nonexistent.

[Flatliner333]

impressed

Wow.....Will you marry me ?

[fishmishin]

UMM I was pretty impressed myself, but ah thats taking it to another extreme, lol !!

[Spider-TW]

I remember when behemoth took exception to my congratulations for athomas' 4000 useful posts, until someone else pointed out that I specified "useful".

[secretweaponevan]

It is a good idea to pay attention to everything athomas says. He is so smart it makes me suspicious.