Shimming an RT

[wjr]

I've put shims in RT on/offs in classic valves before with excellent results. It made the pull significantly more reactive. I'm curious to know what happens when this is done in a Retro valve. Would the pull be more reactive? Would it be the same as increasing the input pressure?

[Coralis]

As i understand it shimming the rt on/off has the same effect as shortening the on/off pin which will make your mag more subject to bounce and sweet spotting. The effect is similar to raising the input pressure.......

[wjr]

Hmmm... then why would anyone spend money to buy an adjustable tank when they could get a pack of $6 shims?

[athomas]

Hmmm... then why would anyone spend money to buy an adjustable tank when they could get a pack of $6 shims?

Its not entirely the same effect. Increasing the pressure increases the amount of kick the trigger returns with. More shims shortens the distance the on-off has to move to allow the chamber to recharge. If you are light on the trigger, then adding shims will do just fine. Anyone who is not as fluid on the trigger or has a tendency to pull and hold, will benefit from the added assist of the higher input pressure.

[peeeto]

...forgive me if this is a dumb question, but how do you shim the RT on/off? where do the shims go?

this is the on/off you're talking about shimming, right? Stock On/Off Assembly

it's not like the ULT, where the shims go in between the top & bottom changing the distance between them...

so do you place the shims in the bottom of the hole where the on/off goes into the valve, before inserting the on/off?


and if the Stock On/Off Assembly isn't the on/off you're talking about, can you please point me to the right one on AGD's online store?

thanks!

[athomas]

You shim the retro on-off assembly the same way you shim a ULT. Put the shims in between the two halves. Because the retro on-off isn't designed for use with shims, you can't use as many as in the ULT so your adjustability is limited, but it does work.

[viper-mayhem]

I put 3 level 10 shims in my RT on/off and I still can't get it to react. But, it is almost impossible to short stroke now. Can I put more in there? I have (7) .005 shims from the ULT, which I'm still trying to tune, that I can put in there.

I have an RT Pro ULE

[athomas]

A retro valve will "react" the same no matter how many shims you use. Reaction is the amount of return force vs the pull force. This is the force you feel against your finger after you fire a shot and is based on the input pressure you use.

The ability to sweet spot is when the return force of the trigger is greater than the pull force but the pull force is greater than the resting force of the trigger. I hope that makes sense. By adding shims you shorten the distance between the release of the sear and the recharge of the valve so the back and forth movement of the trigger is easier to achieve.

So, there is a difference between reaction and sweetspoting. A lot of people confuse the two.