I have recently been singing the praises of my Fac King's consistency and accuracy. Have been using Zan 25.5 slugs at 920 fps with an extreme spread of just 7 FPS. Yesterday it jumped up to 1000 fps for several very consistent shots, then dropped back down to it's tuned 920 fps for a few again super consistent shots. Then it went back up to the 1000 FPS!!! Anybody any ideas? Thanks
FX FX King berserk Fps
- Thread starter yarns
- Start date
Break-in of regulator, if newer gun. My FX regulators are rock steady now but have noted fluctuations early on. WM
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I've had the King for a month or more and it was superb from the word go. What is strange is how it reverts back to it's original FPS for a few shots and then jumps back up by 80 FPS. The "gunsmith" here in the UK replaced the regulator saying that was the problem. Wrong!! It was still the same. They will sort it out believe me, and when they do, I'll post the details. Only started this thread just in case someone else had a similar experience. Thanks for your help.
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Are you 100% sure they are the right slugs? Could be 2 different weights got mixed? Just a thought.
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Absolutely....even opened a new box. It's strange, the FPS doesn't go up or down erratically but jumps to the exact programmed lower FPS, then jumps back up to the higher level it seems to have set itself, and is super consistent when there. There are no in between stops. Seems to me that a valve or spring is getting stuck in an open position. Sorry I am not technically minded.
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Are you sure it isnt the chrony?
Do some shooting with the chrony on and look at the POI when the shot is slower
Do some shooting with the chrony on and look at the POI when the shot is slower
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It's not the chrony.....the RFD was getting similar sets of readings. I am not convinced that their technicians are up to speed (excuse the pun) with a lot of the FX problems. My POI was unaffected at my zero range of 43m. I'm sure that at longer ranges it would be affected. The rifle is back with the RFD, so no chance at present to carry out further tests.
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I'm curious if it can be the valve stem? I know Pantheras had issues with the valves before and since it's essentially a wood stocked Panthera that could be it.
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I wish I knew. No doubt all will be revealed in the next 24 hours. If not, this maybe a time for a rest from FX. Because of the King's weird high/low/high/low FPS behaviour, with nothing in between, it seems to point to a straight forward mechanical issue . FX's QC needs a serious overhaul. These are not cheap rifles, and we should not be doing the beta testing for them. Reminds me of ATN in their early days! Will report back when I have a satisfactory conclusion.....or not! Thanks for all your comments and support.
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I was surprised, but there was no noticeable difference in the POI. A big difference in the rifle's report, and air consumption,
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Are you tuned “to the knee” (or a little below govne that you atmet them 920 but can reach 1000)? Meaning is 1000fps your plateau? Or would more hammer result in even higher speed than 1000fps? If 1000fps is your plateau I’d bet on hammer/spring rotating and grabbing in a specific spot. May be visible when looking at hammer weight and spring and a polish might cure.
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Hi,
Based on the weight of the slug and velocity I am assuming this is an FAC version of the Rifle. The reason I want to check is that FX makes different valve seats and valve pins depending on the power the rifle is intended for. I strongly suspect that you have damaged the valve pin, and it is causing the valve to have different dwell times for the same hammer strike.
I come to this conclusion because I had valve pin problems with my King. Once the pin is damaged there is no fix but to replace it (and likely the seat also). In my case I made the horrible mistake of dry firing the rifle a couple of times when trying to degas the plenum. I forgot to turn down the PW before doing so. The hammer distorted the shape of the head of the valve pin and slightly bent the shaft. As a result, the valve would get stuck open, and I couldn't refill the rifle. I striped the rifle down and saw the valve pin sticking out of the back of the block. I pushed it in and was able to fill the rifle. After that I had trouble getting it to shoot consistently. So, I finally just ordered a new seat and valve and installed them (fairly easy job - just watch the Sub12Airgunners video on the disassembly/reassembly of the Panthera below). No problems after that.
FX has already changed the design of the valve pin from the ones that came on the first Pantheras to make it stronger. But DO NOT dry fire this rifle. Turn the regulator adjustment screw 1/4 turn out to degas the plenum.
Cheers,
Greg
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That sounds like good advice/explanation. I'll pass you comments on to my RFD.
Thanks very much everyone.
Thanks very much everyone.
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That's where it is now. I understand your comments. I have known them since they started down in Paignton and have always had a good rapport with them......BUT cages have to be rattled to get results.
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Had some good deals with Dorset branch which is only 30 minutes away . But shooters I know who had problems with Fx guns have absolutely slaughtered them for so called repairs , most occasions guns came back worse or problems not fixed
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That's why cages have to be rattled. Just spoken to one of the more established "technicians" at SGC, and he knew what the problem was straight away. Exactly as somebody commented earlier.....bent valve pin. I'll keep you updated. Thanks once again everyone.
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