I really hate to post again as I have gotten so much information from you guys and am sure I look totally incompetent. I received my new Crown last week and love the feel, look, trigger etc. It came with a card from the dealer showing they had fired it and it is shooting 880 fps with 18.1 pellets with both dials set at max. and a reg. pressure of a hair over 100. GREAT, that is very close to what I wanted as far as fps goes. BUT, when I fired it on my crono it is shooting only 830 fps with the 18.1's. The crono is new and I have shot it under two of my other guns and it is in my belief very accurate. SO today I turned the reg up to 125 which dropped my fps from 830 to 780. All readings are with both adjustable dials maxed out. I did turn each of them down independently and it did drop the fps more which indicates to me they are both working properly. My intent in buying this crown was to use it to shoot primarily at 50 to 75 yards and hoped the factory tune would produce a fps around 900. I am not mechanical and want to tune for about that fps and leave it alone as I have other guns for other distances. Now I am going to have to monkey around with it, stock off, etc. which I sure did NOT want to do. So what do I do next?
FX Crown FPS confustion
- Thread starter PennyPincher
- Start date
Study tuning methods. Putting the dials at max is rarely an optimal tune. There is always a sweet spot.
Try setting the port dial at High and setting the hammer dial in the middle of the range.
Try setting the port dial at High and setting the hammer dial in the middle of the range.
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Try watching Steves channel/videos very informative.... search his channel for FX tuning vids
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Degas it and lower the reg around 70 bar then work your way up in 5 bar increments, I know nothing about Crown adjustments but it sounds like your hammer strike is to light for the reg setting, one other thing i thought of, is your transfer port on your barrel aligned correctly?
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Check the video DeanB provided, you will need to increase the internal hammer spring adjustment for higher reg pressure.
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This is a bit simplistic, but it sounds like you upped the pressure and didn't have enough hammer spring. There's an adjustment under the knob to increase the "range" of hammer tension.
Don't feel incompetent, the FX rifles Impact and Crown et. al, require you to do some real thinking to tune and asking questions is normal. I'm just now getting to where I can get mine where I want them.
Hang in there, you'll love that rifle.
Don't feel incompetent, the FX rifles Impact and Crown et. al, require you to do some real thinking to tune and asking questions is normal. I'm just now getting to where I can get mine where I want them.
Hang in there, you'll love that rifle.
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I live by the saying he who asks questions is fool for a day, he who doesn't is fool for a lifetime.
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Winner winner….this is spot on. Have to increase hammer pre load when u up reg. You have to take out the safety lever and power wheel to get the stock off. Be careful with the wheel as there are two small ball bearings under there. Insert the 1.5mm Allen into the adjuster with the Allen handle pointed up toward scope rail. Pulling the wrench down toward trigger increases tension. Shoot over the chrono and up the tension until velocity stops increasing.
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Truly Great Videos, grab a notebook and pretend you are in a classroom, take good notes, then apply what you have learned and you will love yourself for doing so. The more you learn, the more you will enjoy shooting that Crown.
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If you want some more information on tuning in general and tuning a Crown in particular, I recommend Sub12Airgunners on YouTube. They are in the UK and do complete tear downs, maintenance, rebuilds, and tuning on lots of air guns - almost all are limited to 12 ft lbs of energy due to the laws in the UK. But they always show the differences with higher powered versions (know as FAC for Fire Arms Certificate in the UK) .
I am attaching their video on tuning a Crown. It is really useful for his explanation of the speed-hammer-spring compression curve. This applies to any airgun which uses a sliding weighted hammer to strike a mechanical valve to release the air pressure to the barrel.
Cheers,
Greg
I am attaching their video on tuning a Crown. It is really useful for his explanation of the speed-hammer-spring compression curve. This applies to any airgun which uses a sliding weighted hammer to strike a mechanical valve to release the air pressure to the barrel.
Cheers,
Greg
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