NEW BARREL INSTALL FX CROWN

[BruceMcClure]

Hi All, I am looking for some guidance. I purchased an FX Crown in .25 a few months ago, I then recently purchased the .30 cal barrel, probe, and magazine. Per the guidance of Airguns of Arizona I was instructed to increase the regulator pressure to just below 150 bar. Prior to increasing the pressure I installed the new components and took it out to get some Chrony numbers the regulator came set for the .25 @ 130. It was shooting an average of about 805 fps. I then increased the regulator to just above 140 and took it out again. It actually now shoots at an average of around 800 to 799. How do I increase the velocity to get at least 830 or greater. Im new to FX and the tuning of any airgun but would like to have a little flater trajectory as the mildot holdover @ 100 is considerable at this velocity. Looking for any ideas.

 

[Glem.Chally]

When you turn up the reg pressure you also need to turn up the hammer spring tensioner, because now there's more backpressure in the plenum. Need to hit the valve harder to open it up the same amount (more air flow). I don't have a Crown but I own it's Father. I assume you're talking about 34gr pellets, keep it at 140 and turn up the power to MAX and see what you get.

 

[STO]

When you turn up the reg pressure you also need to turn up the hammer spring tensioner, because now there's more backpressure in the plenum. Need to hit the valve harder to open it up the same amount (more air flow). I don't have a Crown but I own it's Father. I assume you're talking about 34gr pellets, keep it at 140 and turn up the power to MAX and see what you get.

^This dude knows what he is talking about here. The more efficient and highly engineered an airgun is, the more it sits balanced on a knife-edge for optimized function. 

Generally the Crowns already come set to MAX on the power wheel, so you'll have to remove the power wheel and manually increase spring pressure. I'd recommend going a little further than you think you need, so you can then use the power wheel settings to find your sweet spot for power/air consumption/etc. 

I see this persistent comment about FX Crowns and Impacts coming "needing to be tuned." This is far from my experience, quite the opposite actually. Because they can so readily be tuned, I find they come HIGHLY tuned for a specific caliber and pellet. It is only when you want to change that the less generic tune means you need to really roll up your sleeves and start making careful changes to find that level of optimization again. They're certainly no less tuned than the exquisite FX Royale. 

I hope something in there was helpful mate!  

 

[BruceMcClure]

Thanks I will adjust the hammer spring, I think Ted showed how he does it to tune his crown and impact. Appreciate the quick response this forum rocks!

 

[steve-l]

This works the other way as well. I have a .177 on order for my Crown in ,25. I am pretty certain I will have to back off my hammer spring and regulator pressure to make the gun shoot the small pellet well.

 

[Drumsnguns]

Seems there are a couple of tuning approaches. Ted's and Matt's

I watched and tried them both and I have been going with Matt's. 

Find the best harmonic setting, for the regulator. Start at 100 bar and shoot groups at say 75 yds. then gradually up the pressure until you get your best groups. 145 bar for my Impact. Take notes and measurements.

Then adjust the hammer with the regulator. Turn hammer spring tighter until you hit the highest velocity and it then starts to drop. Then back off just a hair.

Should be good to go. 

I have found 900 fps best with MKII in my Impact with X barrel. Your mileage could vary.

Best of luck and have fun.

KP

 

[FearnLoading]

Check out the YouTube channel Meathead Marksman. He has step by step videos on how to harmonically tune the 25 cal crown and how to increase the hammer spring tension manually. Worth watching those vids. They have everything on them. 

 

[BruceMcClure]

Thank you I have watched that video and will be doing the hammer spring adjustment. I will update with results.

 

[DreamSmoker]

If you are like me??? You want to get that Power..

Hammer spring adjusting can be like climbing a steep hill.. Bit by bit as you turn that screw in and shoot.. Seeing just enough change to see a difference..

I take the stock off.. Put the Power adjust Knob back in place without ball bearings and springs..

Now turn the knob by hand to max and hold.. Next screw that set screw in until you have just enough clearance

so you just feel a slight bit of play between the cam high side on the knob and the set screw...

DONE...