RTI RTI Dual Reg's (??)

[jdanvers]

I keep seeing in posts on facebook ( yeah yeah - I know - consider the source . . . lol ) where guys appear to be talking like RTI has a dual reg setup now - kinda like how the FX's came out with theirs some years ago. I've quick searched here in these forums and out on the the Spanish based site that is generally a good source / reference for all things RT (https://www.rtiarms.shop/) and I don't see anything re: a dual reg.

Just curious - thanks guys

 

[turbospud]

The valve dwelltime adjusting knob is to make sure the valve closes before the projectile leaves the barrel. With this adjustment you can adjust for consistency, accuracy, efficiency and sound output.

how do you know where that point is
is the best way method to keep closing it till the speed drops

 

[Droogmole]

Yes it kind of is. There are more ways you can determine if the valve is closing on the right moment.
When you start tuning the Mora you need to have the valve fully open. The sound output will be very high and the accuracy won't be that great.
As you start closing the dwell time screw you will notice that your accuracy will improve and the sound output will go down.
This has everything to do with to much air leaving the barrel and blowing through the sound barriere at the muzzle. This will also create turbulent air behind the projectile wich can alter its trajectory. That is why you want the valve closing before the projectile leaves the barrel.

At this moment i'm getting good results with my Mora by screwing in the dwell time screw until the velocity is about 20/30fps lower then its highest fps.

In my case i'm shooting 37gr .250 ZAN slug at 984fps.
The maximum velocity i can get with current reg pressure is at around 1010/1020fps.

Just to be clear. I'm not stating that this is the only way to tune your Mora. But it works for me.

 

[weevil]

I close the valve until the speed drops by 10-15fps, making sure that it’s consistent over 5 shots. Then shoot a group and turn down another 10-15fps and see if accuracy improves. Optimize as needed. Mine seems to favor a ~30fps drop for optimal accuracy. It’s a 600mm .22, shooting Altaros 40 grain at 980fps. Second reg is at 175bar. It’s my only AG that defies the common wisdom that Altaros need to be shot at <900fps for accuracy.

As for the dual reg, here’s my take on its advantages. All regs demonstrate some variation in output as a function of input pressure. They output higher than set pressure when their input (tank pressure) is high and vice versa. Having two reduces the variation by stepping down the max pressure that the second reg sees. In my case, the second reg is only dealing with variation ranging from 230-175bar, rather than 300-175. ES from 300-175bar is ~5. There’s a couple more advantages resulting from greater consistency in adiabatic cooling during the shot cycle.

 

[weevil]

Yes it kind of is. There are more ways you can determine if the valve is closing on the right moment.
When you start tuning the Mora you need to have the valve fully open. The sound output will be very high and the accuracy won't be that great.
As you start closing the dwell time screw you will notice that your accuracy will improve and the sound output will go down.
This has everything to do with to much air leaving the barrel and blowing through the sound barriere at the muzzle. This will also create turbulent air behind the projectile wich can alter its trajectory. That is why you want the valve closing before the projectile leaves the barrel.

At this moment i'm getting good results with my Mora by screwing in the dwell time screw until the velocity is about 20/30fps lower then its highest fps.

In my case i'm shooting 37gr .250 ZAN slug at 984fps.
The maximum velocity i can get with current reg pressure is at around 1010/1020fps.

Just to be clear. I'm not stating that this is the only way to tune your Mora. But it works for me.

Touché!

 

[turbospud]

i have a 0.22 700mm barrel firing 34g h and n slugs at 950 fps,
using 180 bar in the second reg,hammer spring set to just open the valve then 1/2 turn in.
it seems the hammer doesnt make much difference to fps as long as its opening the valve against what reg pressure is used.
thanks droogmole and weevil, i will try that with the valve dwell next time out.
i was thinking that when the speed dropped i was doing it wrong.

 

[Peashooter]

When you start tuning the Mora you need to have the valve fully open.

I noticed that somewhere too, and seem valid enough, also make me think about the not easy accessible dwell time adjuster on my Epic Two rifle.

I am a bit sad the forecast for getting a .22 - .25 and .30 Mora are so long, and even longer for the .177 i am tied to by my masters i do not at all respect.
Well forecast on their own page.
"Delivery Time for MORA SNIPER:

• Caliber .177 (4.5mm): Delivery time of 6 to 12 months.
• Calibers .22 (5.5mm), .25 (6.35mm), .30(7.62 mm): Delivery time of 3 to 6 months"

 

[Droogmole]

I close the valve until the speed drops by 10-15fps, making sure that it’s consistent over 5 shots. Then shoot a group and turn down another 10-15fps and see if accuracy improves. Optimize as needed. Mine seems to favor a ~30fps drop for optimal accuracy. It’s a 600mm .22, shooting Altaros 40 grain at 980fps. Second reg is at 175bar. It’s my only AG that defies the common wisdom that Altaros need to be shot at <900fps for accuracy.

As for the dual reg, here’s my take on its advantages. All regs demonstrate some variation in output as a function of input pressure. They output higher than set pressure when their input (tank pressure) is high and vice versa. Having two reduces the variation by stepping down the max pressure that the second reg sees. In my case, the second reg is only dealing with variation ranging from 230-175bar, rather than 300-175. ES from 300-175bar is ~5. There’s a couple more advantages resulting from greater consistency in adiabatic cooling during the shot cycle.

Can you elaborate on the adiabatic cooling in relation to the behaviour of the regs? I needed to look for the meaning of the term "adiabatic" if i understand correctly it has to do with the expansion of a set volume of air as a result of temperature difference?

 

[Droogmole]

i have a 0.22 700mm barrel firing 34g h and n slugs at 950 fps,
using 180 bar in the second reg,hammer spring set to just open the valve then 1/2 turn in.
it seems the hammer doesnt make much difference to fps as long as its opening the valve against what reg pressure is used.
thanks droogmole and weevil, i will try that with the valve dwell next time out.
i was thinking that when the speed dropped i was doing it wrong.

You are correct. Of i where you i would just trust my instinct. The hammer spring in the Mora doesn't have the same function as the hammer spring in a rifle with a traditional valve. RTI calls their valve a "binary valve" within the valvestem there is a second air schannel.
As soon as you hit the valve with the hammer.
The pressure in your plenum opens the valve completely. The back pressure of your projectile closes the valve by creating a pressure behind the valve in a separate cilinder. This is a carefully engineerd piece of genius in my opinion. It makes for a very smooth shot cycle. Because the hammer and hammer spring don't need to push against the air pressure to open the valve.

In case of the Mora the hammer spring tension is only adjusted to increase consistency. You can still reduce FPS using the hammer spring. But it will introduce a lot of inconsistency. And it is not meant for that. The reg pressure determines the velocity. Hammer spring and valve dwell time are only for efficiency, accuracy and consistency.

 

[turbospud]

You are correct. Of i where you i would just trust my instinct. The hammer spring in the Mora doesn't have the same function as the hammer spring in a rifle with a traditional valve. RTI calls their valve a "binary valve" within the valvestem there is a second air schannel.
As soon as you hit the valve with the hammer.
The pressure in your plenum opens the valve completely. The back pressure of your projectile closes the valve by creating a pressure behind the valve in a separate cilinder. This is a carefully engineerd piece of genius in my opinion. It makes for a very smooth shot cycle. Because the hammer and hammer spring don't need to push against the air pressure to open the valve.

In case of the Mora the hammer spring tension is only adjusted to increase consistency. You can still reduce FPS using the hammer spring. But it will introduce a lot of inconsistency. And it is not meant for that. The reg pressure determines the velocity. Hammer spring and valve dwell time are only for efficiency, accuracy and consistency.

as i have only been used to old fashioned hammers and springs,this system takes a bit of learning.

knowing how to achieve the best results is the hard bit at the moment

 

[Droogmole]

The way i gained good results is by pretty much following what RTI tells you in their manual. I'll try to make a short explanation.


1. Determine your pellet/slug seating deph. In the manual it is called "head space" You should adjust the pin prode in such a way that your pellet/slug kind of sticks in the breach of your barrel. (where the rifling starts)
Just partitially pull back the cocking handle to insert a pellet/slug (completly cocking it won't be necessary)
Then close the cocking handle and open it again. Then take a long stick or whatevver that fits inside your barrel.
Feed in the stick trough the muzzle of the barrel until it touches the pellet/slug. If you can feel that the projectile is a little bit stuck you are pretty much on the right spot. Repeat this with a few more projectiles to make sure they all pretty much stick the same way in the breach.

2. Open up the dwell time screw completely and turn your hammer spring to max. Then turn your reg pressure to a pressure where you think the projectile will have pretty much the right velocity. It is better to be on the safe side and keep the reg pressure a little lower.

3. load a mag and shoot lets say 5 times while measuring your speeds. If your volocity is exactly where you want it or it is lower.
Then you need to increase reg pressure. If velocity is more then 30fps higher, decrease reg pressure.
You can decrease reg pressure by unscrewing the bleed screw (above the reg pressure gauge) just a little until it starts to lose air.
Then slowly turn the regultor screw counterclockwise to lower the reg pressure. After adjusting the reg fire 3 to 5 blanck shots to settle in the reg.

repeat the proces to the point you are about 20-30 fps higher then you want to be. So lets say you want your projectile to have a muzzle velocity of 950. Then at this point it should fly at around 980fps. Don't worry about consistency an accuracy yet (this will probably be all over the place) If you have a velocity fluctuation of about 10/15fps its fine at this point of the tuning proces.

4. Start turning in your valve dwell time screw. First start with 1/2 turns. Then as soon as you see your velocity drop start turning it bij 1/4turns.
Remember, after every adjustment you need to take 3-5 blanck shots to let everything settle. Do this until you are on your desired velocity
(about 20-30 fps lower then max velocity on set reg pressure) At this point you will notice that your groups are getting better and the noise level of the shot is a lot lower.

5. unscrew the hammer tension screw to its max. When looking at the back of the buttstock you will be able to see the hammerspring tension screw and its treading. Screw the screw counterclockwise until it is flush with the threading. Now fire a blanck shot.
You will notice that there will be no sound or just a little bit. Start increasing the hammer spring tension until you hear nice loud bang from the muzzle.
Now insert a mag and fire a few shots. Ideal the velocity should be a bit lower then when you had the spring tension at max.
This way you know for sure the hammer spring is not over powering the valve. Increase the hammer spring by 1/4 turns to get on the disired velocity.
Then, when you are there. Give it another 1/4 turn to make sure the valve opens up correctly.

At this point your STD DEV and EX SPR should be pretty good. By pretty good i mean STD DEV<5fps EX SPR<15fps.

6. completly fill the rifle and shoot it until it starts to drop of the reg. If you can see in your shot string that the velocity is slowly starting to drop, it means that the pressure difference between your 1st and 2nd reg is to high. RTI has mentioned in their manual a pressure difference of 20-50 bar and they say that the 1st reg is set to about 220bar. Later they corrected it by saying 200bar. But your 2nd doesn't go higher then 200bar.
So there is no way to know for sure.
That being said. To lower the 1st reg pressure you need to completly degass the rifle and then unscrew the bottle.
The explanation RTI gives for adjusiting the 1st reg is a little confusing to me. So i figured it out myself. By turning the allen screw in (clockwise) you will lower the pressure. This is the other way around with the 2nd reg. That is because they are both build in a different way.

Unfortunatly i don't know what the pressure drop is per rotation of the allen screw. The only way to check your set reg pressure is by turning in your 2nd to the max of 200bar and then fill up the rifle. At this point your regultor gauge is showing the pressure of the 1st reg.

Example. Your 2nd reg is at 130bar. Then the first reg should be between 150 and 180.

After you have set the 1st reg you can dail the 2nd reg back to the pressure you had it on before you adjusted the 1st reg.

When you have completly filled the rifle back up and your regs are the way they need to be, you can shoot another full string.
If the regs are behaving as they should. you will have a nice straight shot string with at the end a significant velocity drop.
And i mean like 30+fps difference of each following shot.

At this point the rifle should be pretty consistent, quiet and delivering a smooth shot cycle.

Here is a little more info on my experiences during the tuning proces.

You will notice that the velocity drop will start before the bottle pressure is the same as the reg pressure. This is normal.
A regulator needs a minimal pressure difference to be ably to regulate. I think it is somewhere around 15-20bar difference per reg
(this al depends on set reg pressure and construction/enginering)
This means that you could experience a significant velocity drop when the bottle pressure is still at around 40bar higher then the reg pressure.
I don't know for sure if this is correct but this is what i am experiencing with my regulated rifles and the Mora.
The minimun pressure difference depends on the contrruction and set pressure of the regulator.
Mine is set at 134bar. And 1st reg is set at 178. When the bottle pressure is at around 160-170bar the velocity starts to drop.
My FX maverick has a minimun pressure difference of about 12 bar per reg. The reg is set at 154bar.
This means that when the bottle pressure is down to 180bar. The velocity starts to drop.

when you have tuned the rifle like this and you still have a big FPS spread. Then try upping the spring tension bij 1/8 of a turn.

If at this point you want to experement with different velocitys to determine what works best. You can up the hammer spring another 1/2 turn and just increase the reg pressure to increase velocity. You don't have to adjust the dwelltime screw anymore.
By increasing the reg pressure to increase velocity the back pressure of the pellet/slug will be higher which means the valve will close faster.
This doesn't have a negative effect on the accuracy (maybe on consistency)
Only when you lower the regultor pressure to decrease velocity. The back pressure to close the valve will be less. In this case the valve will stay open longer wich might introduce turbulent air at the muzzle. This will then effect accuracy. But you will be able to hear this. The shot wil be louder.

I hope this will at least give you some good results with the Mora.

If anyone has anything to add or correct. Please do so!

 

[turbospud]

thanks droogmole,i will try that,there is a few steps in there that im not doing correctly

explanation like this should be in the manual

much appreiciated