FX FX Maverick VP .22 tuning for lighter pellets(15.89gr and 18.13gr)

[ssg]

FX Maverick VP .22
Barrel Length 500mm

I got this gun this week and I also have insane amount of lighter pellets and I would like to shoot these before I move to heavier pellets.

I am currently shooting 50 yards and I am getting sub 1/2" groups with 15.89gr pellets which I am happy with.

I started the tuning by lowering first regulator to 100 bar and second to 60 bar. I then slowly moved up to around 70 bar and stopped there as the groups at 50 yard started to be good. I did not have any specific fps target but it settled around 890 fps. I am getting ES 12 fps and STD 3.8 which is quite decent, could be better but it is ok.

The issue is however that I am hitting what some call "plateau velocity". Here are the fps for each power setting.

1. 875
2. 890
3. 891
4. 889
5. 894
6. 898
7. 888

If I have understood correctly currently my HS is overpowering the valve. My understanding is that to get the best possible efficiency and performance you should tune your Maverick so that the heaviest pellet(in this case 15.89gr as it is currently one I am trying to get rid of) is tuned to power setting 6 or 7. How do I achieve this, or is it even possible for such a light pellet.

I do not know if my hammer weight is 7g or 11g, apparently these new Mavericks can come with either one and I haven't taken it out yet.

My IHS is set to factory default.

Can someone explain how does IHS and hammer tension work together with the set pressure. I have watched dozens of YT videos, read tens of forum threads but I still don't quite understand it.

What is the correct method to achieve around 875 to 900 fps with 15.89 pellet and have the gun properly tuned at the same time? Mess around with IHS, increase the 2nd regulator pressure?

 

[MongooseV8]

The force your hammer hits the valve is a combination of the hammer weight, and the hammer spring power. The hammer spring power/tension can be increased or decreased by either; changing the spring itself or adjusting the preload. Increasing preload will increase the spring rate and therefor the force it propels the hammer weight/assembly into the valve. You can try lowering the hammer spring preload, or swap out to a lighter spring/hammer weight. The other option that might work depending on your specific rifle is increasing the reg pressure higher so the hammer is more balanced. Then you can adjust your power wheel lower to lower your velocity (within reason). The whole system needs to be balanced, and usually should all be adjusted together. The valve also has a varying degree of resistance to the hammer system strike. The higher the set reg pressure, the harder the valve needs to be hit to open the same distance. There are other factors like the valve return spring force, and dwell time (how long the valve is open) but thats the basic idea.

 

[ssg]

The force your hammer hits the valve is a combination of the hammer weight, and the hammer spring power. The hammer spring power/tension can be increased or decreased by either; changing the spring itself or adjusting the preload. Increasing preload will increase the spring rate and therefor the force it propels the hammer weight/assembly into the valve. You can try lowering the hammer spring preload, or swap out to a lighter spring/hammer weight. The other option that might work depending on your specific rifle is increasing the reg pressure higher so the hammer is more balanced. Then you can adjust your power wheel lower to lower your velocity (within reason). The whole system needs to be balanced, and usually should all be adjusted together. The valve also has a varying degree of resistance to the hammer system strike. The higher the set reg pressure, the harder the valve needs to be hit to open the same distance. There are other factors like the valve return spring force, and dwell time (how long the valve is open) but thats the basic idea.

Thank you. I think I now understand bit better how the valve and hammer works together.

So first I can try decreasing the IHS and see what happens. That one is easy to reset if it does not work. Basically this will work if I can get the hammer tension low enough for hammer to open the valve just right distance. This method will not however work if the valve resistance and hammer power are still too unbalanced in this case the hammer strike is still too powerful.

If that does not work, I can try to increase the 2nd regulator pressure and find better balance by increasing the valve resistance and adjusting hammer power by using lower power wheel values like 1 to 4 and adjusting the IHS to match the valve resistance better.

Changing hammer spring, or hammer weight requires some optional parts and some disassembly to find out what weight hammer I have so I will look into these if the two methods above do not work.

 

[MongooseV8]

Yessir sounds like you got it under control now have fun and be safe.

 

[ssg]

I reduced the IHS all the way down, that helped a bit but not enough so I increased the pressure to around 75 bars. Power settings 6 and 7 were however still the same fps , so the hammer was still overpowering the valve. I used PS 5 with IHS all the way down.

First 10 shot string had 4 fps spread and 1.2 STD. Over time it settled to 11 ED and 4.7 STD. Average fps was 899 on 15.86gr


My first 5 pellet 50 yard group was like this.

However I wasn't able to repeat it and all the other groups were much less consistent and some where all over the place but I guess that could be an user error as the fps was really consistent.

I could tweak this a bit more, but I have only 1.5 tins of 15.86gr left so I think I will be happy with this and then I will tune it to 18gr which should be slightly easier.

 

[seangabrell]

Weather your on 1 or 7 won’t matter. You want to tune for the pellet/ slug you’re shooting. I have a .25 sniper but also have a .22 600 mm barrel that I swap out occasionally. If I’m shooting .25 25.39’s or 33.95’s or in .22 18.13’s or 25.39’s the rifle has to be re-tuned for the projectile. There’s no happy reg setting for both and just play with the wheel. I’ve found tuning to 10-20fps below max to get the best ES/SD’s while still having a somewhat tame shot cycle. Obviously 10fps below the max will be slightly tighter but also a little more jumpy. Now if you’re shooting under 50 yards the spreads won’t be as visible in POI but once you push it out further it will be considerably noticeable.