Fx Crown tuning

[hosehead]

Hello I have seen 2 options for manually tuning the hammer spring and wanted input of which might be better.

First choice is adjusting hammer spring to a point that was called neutral ( a point in which turning power wheel from min to 1 just begins to move the hammer. You then back off hammer spring 5 turns and your .22 cal is supposed to be sitting at 850 fps at max power wheel setting to fall within optimum fps for 18.13 gr pellets.

Option 2 was turning the hammer spring to max allowing power wheel to still rotate. You then using your chrono, take a shot, record fps, crank down spring tension , rinse and repeat for 18-25 shots.
You then look at recorded shot data to identify when fps begins to drop then dial back hammer spring to that position

Curious which option might be the better choice as looking to tune .22 in the 850-900 fps range using 18.13 gr with maximum efficiently and of course accuracy

Sorry for the long winded question

Thx

 

[Jlowe]

Which Crown set-up do you have? Also, where are you at right now?

 

[hosehead]

Fx crown continuum tuning 380 mm barrel. Where am I at? Meaning location or in tuning process ?

 

[Jlowe]

Yeah, like reg setting.

 

[hosehead]

Yeah, like reg setting.

Currently Regulator set at 120 Bar

 

[Trucker3573]

Not sure about the crown but my Maverick works it’s best by far when operated near the max velocity whatever reg pressure you have chosen will produce. It’s a bit of trial and error to find that perfect combo. I usually choose a reg pressure. Set the hammer spring wheel to max and use the internal adjuster to find that max point for the given reg pressure. It also depends how anal on extreme spread you want to be. I probably tend to be too anal about it. I know many people use one tune for mult weight projectiles. Maybe I just haven’t figured it out but the extreme spreads will be beautiful turned up for that heavy pellet but not so good at all when you crank it down for the lighter stuff. I tune for one projectile at a time because of this.

 

[hosehead]

Not sure about the crown but my Maverick works it’s best by far when operated near the max velocity whatever reg pressure you have chosen will produce. It’s a bit of trial and error to find that perfect combo. I usually choose a reg pressure. Set the hammer spring wheel to max and use the internal adjuster to find that max point for the given reg pressure. It also depends how anal on extreme spread you want to be. I probably tend to be too anal about it. I know many people use one tune for mult weight projectiles. Maybe I just haven’t figured it out but the extreme spreads will be beautiful turned up for that heavy pellet but not so good at all when you crank it down for the lighter stuff. I tune for one projectile at a time because of this.

Great points and thanks

I am thinking that max hammer spring to match regulator pressure is better for specific pellet. On the other hand, the other tune is probably better for a generic tune to accommodate a range of pellets and barrels without having to go back inside the gun

Thank you

 

[Trucker3573]

Great points and thanks

I am thinking that max hammer spring to match regulator pressure is better for specific pellet. On the other hand, the other tune is probably better for a generic tune to accommodate a range of pellets and barrels without having to go back inside the gun

Thank you

Yep exactly. My Maverick when set like that will be less than 10 fps spread. Drop power wheel down to 5 and that spread opens up to like 25-30 fps. Depending on what you are doing with it that may be fine. Just bugs me.

 

[NAProf]

HI,
Just thought I would add my 2 cents. I have a Crown MkII with a 500 mm barrel in .177. I have found that the lower the reg pressure the better my accuracy. I am shooting 13.4 gr FX pellets at 825 fps for Hunter Field Target. Surprisingly, this is extremely accurate out past 50 yds. To do this my reg pressure is 105 bar and the external hammer adjuster is at 19. I take apart the rifle and measure the length of the micro adjuster. It is 3.5mm. I am also running on the medium setting for the transfer port.

The micro adjuster moves in and out 0.5mm per complete turn of the screw. The difference between any two numbers on the power wheel is almost exactly 0.2mm over the whole range of settings. So, 1 revolution of the micro adjuster is 2 1/2 clicks on the power wheel. The results on the hammer are exactly the same. So adjusting the micro screw really just moves your power wheel setting for the same hammer spring compression. This means it almost doesn't matter where you start with the micro adjuster because you have a larger range of hammer spring compression already. I just use the micro adjuster to tweak a little on a particular power wheel setting.

I am going to attach a You Tube video from my favorite airgun site. This is Sub12 Airgunners, a UK site that pretty exclusively works on the UK spec sub 12 ft lbs of energy rifles. He has a bunch of videos on the Crown Mk II and shows the differences between the UK spec and the FAC (Firearms Certificate - same as US) spec rifles. His video on tuning the Crown explains a lot of why you tune the way he suggests. It is worth the 10-15 minutes to watch. They you can look at Part 2 of this. Then his whole collection of crown disassembly and assembly, etc vidoes. Have fun!
Cheers.
Greg

 

[hosehead]

HI,
Just thought I would add my 2 cents. I have a Crown MkII with a 500 mm barrel in .177. I have found that the lower the reg pressure the better my accuracy. I am shooting 13.4 gr FX pellets at 825 fps for Hunter Field Target. Surprisingly, this is extremely accurate out past 50 yds. To do this my reg pressure is 105 bar and the external hammer adjuster is at 19. I take apart the rifle and measure the length of the micro adjuster. It is 3.5mm. I am also running on the medium setting for the transfer port.

The micro adjuster moves in and out 0.5mm per complete turn of the screw. The difference between any two numbers on the power wheel is almost exactly 0.2mm over the whole range of settings. So, 1 revolution of the micro adjuster is 2 1/2 clicks on the power wheel. The results on the hammer are exactly the same. So adjusting the micro screw really just moves your power wheel setting for the same hammer spring compression. This means it almost doesn't matter where you start with the micro adjuster because you have a larger range of hammer spring compression already. I just use the micro adjuster to tweak a little on a particular power wheel setting.

I am going to attach a You Tube video from my favorite airgun site. This is Sub12 Airgunners, a UK site that pretty exclusively works on the UK spec sub 12 ft lbs of energy rifles. He has a bunch of videos on the Crown Mk II and shows the differences between the UK spec and the FAC (Firearms Certificate - same as US) spec rifles. His video on tuning the Crown explains a lot of why you tune the way he suggests. It is worth the 10-15 minutes to watch. They you can look at Part 2 of this. Then his whole collection of crown disassembly and assembly, etc vidoes. Have fun!
Cheers.
Greg

Hi Greg…. Thank you for the excellent data points! I have never manually adjusted the hammer spring and it was set at reg pressure of 120 bar when I received it. With 15.89 gr Hades, I was getting 850 fps at max power wheel setting. I wanted to shoot a little higher so i increased the regulator to 130 and the fps dropped to 830 fps. This is what started my search for a best way to increase hammer spring. I want to set it and not have to take it apart again as I think I will stay with 15.89 gr as this suites what I need for pest control

Rick

 

[orangeokie]

HI,
Just thought I would add my 2 cents. I have a Crown MkII with a 500 mm barrel in .177. I have found that the lower the reg pressure the better my accuracy. I am shooting 13.4 gr FX pellets at 825 fps for Hunter Field Target. Surprisingly, this is extremely accurate out past 50 yds. To do this my reg pressure is 105 bar and the external hammer adjuster is at 19. I take apart the rifle and measure the length of the micro adjuster. It is 3.5mm. I am also running on the medium setting for the transfer port.

The micro adjuster moves in and out 0.5mm per complete turn of the screw. The difference between any two numbers on the power wheel is almost exactly 0.2mm over the whole range of settings. So, 1 revolution of the micro adjuster is 2 1/2 clicks on the power wheel. The results on the hammer are exactly the same. So adjusting the micro screw really just moves your power wheel setting for the same hammer spring compression. This means it almost doesn't matter where you start with the micro adjuster because you have a larger range of hammer spring compression already. I just use the micro adjuster to tweak a little on a particular power wheel setting.

I am going to attach a You Tube video from my favorite airgun site. This is Sub12 Airgunners, a UK site that pretty exclusively works on the UK spec sub 12 ft lbs of energy rifles. He has a bunch of videos on the Crown Mk II and shows the differences between the UK spec and the FAC (Firearms Certificate - same as US) spec rifles. His video on tuning the Crown explains a lot of why you tune the way he suggests. It is worth the 10-15 minutes to watch. They you can look at Part 2 of this. Then his whole collection of crown disassembly and assembly, etc vidoes. Have fun!
Cheers.
Greg

I am a big fan of Sub 12 myself, also withe the Benjamin Alela and the BSA R10 and AA S510

 

[NAProf]

Hi Greg…. Thank you for the excellent data points! I have never manually adjusted the hammer spring and it was set at reg pressure of 120 bar when I received it. With 15.89 gr Hades, I was getting 850 fps at max power wheel setting. I wanted to shoot a little higher so i increased the regulator to 130 and the fps dropped to 830 fps. This is what started my search for a best way to increase hammer spring. I want to set it and not have to take it apart again as I think I will stay with 15.89 gr as this suites what I need for pest control

Rick

Rick,
Jeff of Sub12 Airgunners shows in his video why increasing the regulator pressure caused a drop in velocity, Yes, you do need to adjust the hammer spring compression so that you get the valve to stay open long enough. But you could also just be blowing air out the end of the barrel after the pellet leaves the barrel, doing nothing for velocity but messing up accuracy. That is why you want to start the tune at a low pressure and work your way up to the "knee" in the video. Then if you don't have the velocity you want, bump up the pressure and repeat the process. This approach works with every regulated air rifle. It does kind of make tuning an "art", but it is sweet when you find that right spot where you get your velocity with small ES and SD and can then tweak for accuracy. Lots of pellets/slugs are shot, but it's really kind of fun.
Cheers,
Greg

 

[Jlowe]

Hi Greg…. Thank you for the excellent data points! I have never manually adjusted the hammer spring and it was set at reg pressure of 120 bar when I received it. With 15.89 gr Hades, I was getting 850 fps at max power wheel setting. I wanted to shoot a little higher so i increased the regulator to 130 and the fps dropped to 830 fps. This is what started my search for a best way to increase hammer spring. I want to set it and not have to take it apart again as I think I will stay with 15.89 gr as this suites what I need for pest control

Rick

I have 2 Crowns. One in 22cal and one in 25cal. Take the stock off and increase the IHS to almost max power. Not quit max, but almost max. That is if you want to set it and forget it. Other wise, if your looking to max out at 900fps with an 18 grain JSB, that shouldn't take long,. When you increase reg pressure and the FPS goes down, that is an indicator that your Internal hammer spring is se too low. FX does that on all their crowns. My 22 with 500mm barrel came maxed out at 30 foot pounds.

 

[pcpSWE]

I have 2 Crowns. One in 22cal and one in 25cal. Take the stock off and increase the IHS to almost max power. Not quit max, but almost max. That is if you want to set it and forget it. Other wise, if your looking to max out at 900fps with an 18 grain JSB, that shouldn't take long,. When you increase reg pressure and the FPS goes down, that is an indicator that your Internal hammer spring is se too low. FX does that on all their crowns. My 22 with 500mm barrel came maxed out at 30 foot pounds.

What do you mean with IHS?
Is it hammer spring? How do I adjust it to what you mentioned? Any mesurements or guides to follow?