Hello. I am pretty new to this. I have had a Crown Mk2 in .30 with 600mm barrel for about 8 months. I like the gun a lot but am not getting the velocity I think I should and there is a lot of.drop at 100 yds. 45 gr is only at about 810. I have been told I need to adjust the internal hammer spring tension.i haven't done that yet but plan to. My question is : are there other recommendations for mods that will allow higher velocities- at least the option at full external adjustment for higher power? Thank you for ideas.
Mods to improve crown mk2 performance
- Thread starter Dougth
- Start date
Dougth;
I am by no means an expert tuner. I do have a Crown MK2 and have gone down the road you seem to be starting on. Mine is a 25 caliber Continuum with a 380mm and a 600mm barrel. As delivered the gun shot JSB Kings and King Heavy pellets with superb accuracy. I ended up installing the 600mm barrel and trying to shoot slugs.
As delivered my Crown was incapable of pushing 25 caliber slugs at 900 fps or more. The hammer spring and weight can't adequately open the valve for regulator pressures above 135 (+/-) Bars. To get much higher velocities requires increasing the regulator pressure to 150 Bar, or more. You will need a slug power kit to make this work.
Good luck.
George
I am by no means an expert tuner. I do have a Crown MK2 and have gone down the road you seem to be starting on. Mine is a 25 caliber Continuum with a 380mm and a 600mm barrel. As delivered the gun shot JSB Kings and King Heavy pellets with superb accuracy. I ended up installing the 600mm barrel and trying to shoot slugs.
As delivered my Crown was incapable of pushing 25 caliber slugs at 900 fps or more. The hammer spring and weight can't adequately open the valve for regulator pressures above 135 (+/-) Bars. To get much higher velocities requires increasing the regulator pressure to 150 Bar, or more. You will need a slug power kit to make this work.
Good luck.
George
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Watch this first for a proper understanding of the rifle, and how to tune. Then you should be able to start your journey.
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I have a Crown MKII in 25 with the 600mm barrel.
When it came from the factory I could not get the NSA 26.5 gr slugs to 900 fps.
I am now shooting those slugs at around 960 with no additions to the gun.
First make sure you have your power selector on high then pull the barrel and make sure you are using the slug port. Then, adjust the internal hammer spring screw. It is much easier to adjust if you remove the adjuster from the gun.
The way mine was delivered there was a ton of power left to be had. If you want to shoot 33+ gr slugs you will most likely need to go the modification route. I keep to the lighter slugs to avoid all the additional stuff.
My Crown is set up so that on max I shoot the slugs @ 960 and turn the power wheel to 11 and it shoots the FX 25.whatever pellets at 885’ish with very good accuracy from both projectiles.
my reg is set at 140.
When it came from the factory I could not get the NSA 26.5 gr slugs to 900 fps.
I am now shooting those slugs at around 960 with no additions to the gun.
First make sure you have your power selector on high then pull the barrel and make sure you are using the slug port. Then, adjust the internal hammer spring screw. It is much easier to adjust if you remove the adjuster from the gun.
The way mine was delivered there was a ton of power left to be had. If you want to shoot 33+ gr slugs you will most likely need to go the modification route. I keep to the lighter slugs to avoid all the additional stuff.
My Crown is set up so that on max I shoot the slugs @ 960 and turn the power wheel to 11 and it shoots the FX 25.whatever pellets at 885’ish with very good accuracy from both projectiles.
my reg is set at 140.
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Great idea. Will do. thanks. I have watched other videos from his channel and really like him.
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thank you all for your suggestions. As in the video I increased the hammer spring such that when I turn the dial, I can barely get it to turn to max. I probably increased it about 3-4 full turns. So that is pretty much max hammer spring adjustment I guess. It is shooting much faster now. 44g are about 915, but it seems the spread is pretty high. there is a pretty large standard deviation. So I am not sure what that is about. My reg pressure is about 155.
If I turn it down the hammer spring wheel to about 17, the 44g are at about 860 and I seem to get a pretty good shot count. I have made a mistake though- Several times I have tried to turn hammer spring knob when the gun was cocked. I only turned it a click or two but sort of forced it before realizing what I was doing. I am curious if you think I have damaged the gun significantly by doing that. When I looked at the internal screw it looked to have a gouge taken out of the threads, and the end of the screw that interacts with the cam appears slightly damaged. From what I can tell it works ok though. The knob turns smoothly.
Can anyone provide a link to the crown slug kit? I am not finding that. Only impact. Maybe I am looking in wrong place. Thank you.
If I turn it down the hammer spring wheel to about 17, the 44g are at about 860 and I seem to get a pretty good shot count. I have made a mistake though- Several times I have tried to turn hammer spring knob when the gun was cocked. I only turned it a click or two but sort of forced it before realizing what I was doing. I am curious if you think I have damaged the gun significantly by doing that. When I looked at the internal screw it looked to have a gouge taken out of the threads, and the end of the screw that interacts with the cam appears slightly damaged. From what I can tell it works ok though. The knob turns smoothly.
Can anyone provide a link to the crown slug kit? I am not finding that. Only impact. Maybe I am looking in wrong place. Thank you.
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Big no no with these fx guns, to turn power wheel adjustments after it’s been cocked.
You don’t really break anything to the point of the gun not shooting, but those gouges on the rear cam behind the power wheel isn’t good, either. Depending on the severity of the gouge, you won’t be able to rely on a certain FPS on a certain setting to be consistent on a day to day adjustment of that power wheel.
I’m not a crown owner but I follow most of the crown threads. FX supossedly has a new one with more increment settings, or you can contact a member on here that has made and sold his machined power wheel to members of not only crown, but impacts, also. I’ve heard his power wheels are built well and don’t gouge easily. Hopefully he reads this and pipes in
You don’t really break anything to the point of the gun not shooting, but those gouges on the rear cam behind the power wheel isn’t good, either. Depending on the severity of the gouge, you won’t be able to rely on a certain FPS on a certain setting to be consistent on a day to day adjustment of that power wheel.
I’m not a crown owner but I follow most of the crown threads. FX supossedly has a new one with more increment settings, or you can contact a member on here that has made and sold his machined power wheel to members of not only crown, but impacts, also. I’ve heard his power wheels are built well and don’t gouge easily. Hopefully he reads this and pipes in
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Here’s a link to the thread where Monte discusses his new powerwheel
www.airgunnation.com
Its time to show the world my 19 step Impact power wheel
PM sent, and thank you for developing this. Mike
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Have you considered adding a hammer weight? If so, you should call Bullet Central and speak to Chris in airguns. They sell a tungsten hammer weight and modified springholder for a drop in modification.
When I installed it and was adjusting it, I had a shot string with .25 JSB 33.95 MKII at an average of 1040 fps (five shots) with an SD of 2.1. Regulator was at about 140 bar. If you would like me to cover how I tuned it, PM me and let me know. You will need a chronograph.
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Here’s a link to the thread where Monte discusses his new powerwheel
Its time to show the world my 19 step Impact power wheel
PM sent, and thank you for developing this. Mike
And IMHO Mont’s power wheel is a must have upgrade for any FX guns. Except for Maverick since I don’t think he makes one for Maverick.
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