I recently purchased my wildcat Mk2 and wanting some input on why my first shot cold bore is off. All following shots are spot on with the exception of a flyer at times. It doesn't matter if I fill it the night before to 220 bar let everything cool to room temp the first shot of the day is always off. Would like to know if anyone else is having this issue or how to fix the problem. My Wildcat mk2 has the new AMP regulator in it. I have not touched any of the factory settings. Thanks Grover
FX Wildcat .25 Cold Bore first shot POI change
- Thread starter Grover
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Even good regulators will typically exhibit some creep when new. Try putting a tin of pellets through it...that will help break in the regulator’s valve seat.
The Wildcat doesn’t have a 2nd gauge for monitoring the reg’s output pressure, does it? Maybe I overlooked it on the parts diagram. If it does, you will be able to know for certain if that is the issue.
Careful tuning will also make the gun less sensitive to pressure variations. Typically you would do that by increasing the hammer spring preload until you find the maximum velocity the gun will produce. Then back it off until you have about 95 - 97% of that maximum.
The Wildcat doesn’t have a 2nd gauge for monitoring the reg’s output pressure, does it? Maybe I overlooked it on the parts diagram. If it does, you will be able to know for certain if that is the issue.
Careful tuning will also make the gun less sensitive to pressure variations. Typically you would do that by increasing the hammer spring preload until you find the maximum velocity the gun will produce. Then back it off until you have about 95 - 97% of that maximum.
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Whether the first shot is low or high will depend on the amount of hammer strike.
That is, if the hammer strike is too weak, the gun will be operating in a condition of partial valve lock and the first shot will be slower.
Conversely if the hammer strike is too strong, it will easily overcome the higher pressure that is holding the valve closed, resulting in a first shot that is faster.
By getting the hammer strike adjusted just right, the gun can self-regulate and maintain a stable velocity even when the regulated pressure varies. This self-regulation is the same principle by which a traditional unregulated PCP maintains a stable velocity over a fairly wide pressure range.
That is, if the hammer strike is too weak, the gun will be operating in a condition of partial valve lock and the first shot will be slower.
Conversely if the hammer strike is too strong, it will easily overcome the higher pressure that is holding the valve closed, resulting in a first shot that is faster.
By getting the hammer strike adjusted just right, the gun can self-regulate and maintain a stable velocity even when the regulated pressure varies. This self-regulation is the same principle by which a traditional unregulated PCP maintains a stable velocity over a fairly wide pressure range.
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You say "first shot of the day", but actually how long do you need to wait between shots for the initial shot to be off zero ?
Could it be just an hour or two ?
Could it be just an hour or two ?
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The first shot is high at 10 oclock above the POI by 1.5 inches at 50 yds . When shooting through chrono avg fps is 865 with 25.39. As far as the regulator break in I have run 6 tins of JSB 25.39 & 33.95 King MkII through my wildcat.
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Okay yeah the reg has had ample opportunity to break in. So no second gauge?
1.5in at 50 is a lot. What is the velocity of the first shot? Trying to see if it makes sense.
1.5in at 50 is a lot. What is the velocity of the first shot? Trying to see if it makes sense.
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Yep … could be as little as 30 minutes or less. Breaking in the gun with a few tins of pellets will give you a better idea of how the gun is going to react to cold shots. Some regulators will get broken in just right and be pretty darn close on that first shot … other guns might need a little TLC with an adjustment to the HST. Mine is always off by just a little on that first shot but not enough to make a difference. I'll not worry to much about a quarter inch at 65 yards. Outside temperature fluctuations will have more effect on the pellet than that.
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So I am thinking over night I must be having some pressure creep as the first shot is always high and to the left. Before I play with the hammer spring adjuster I will set up my chrono and see if the first cold bore shot has a higher velocity over 3-4 days. Included is a group I get at 50 yds after getting warmed up 25.39 gr JSB
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If I wait 4-6 hours POI doesn't change. The target I put above that is 16 shots. Very happy with FX Wildcat will hopefully get the issue resolved with just HSA. Maybe over time the problem will resolve its self. Just frustrating when you have a Squirrel on the bird feeder and you think your going to make a clean head shot and your off r/t cold bore POI being off.
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Yes sir, the squirrel on the feeder scenario is precisely why I cannot stand a creeping regulator.
I’ll keep an eye on the thread.
I’ll keep an eye on the thread.
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If there is no creep in 4 to 6 hours, just take a shot or two before you start hunting and you should be good to go.
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Okay I've been thinking about this some more and there are a couple of things that cast some doubt on it being a creep problem. Firstly, 4 or 6 hours is a long time for there to be no observable change in POI, especially at 50 yards and especially given there is an eventual 1.5 inches of trajectory change.
Secondly, to produce a 1.5 inch elevation change, the velocity of the first shot would have to be about 1000fps. This is what Chairgun says using Kings at 865fps. Now if the elevation difference were only 1 inch, the velocity would only have to be 950fps...still quite a big jump. In either case, I would expect there to be a rather obvious change in the report.
Here are a couple new thoughts/questions I want to throw out:
1. Is the gun being stored with upward pressure applied to the barrel...standing in a corner or on a rack?
2. Were you shooting in the extreme cold? If so, bear in mind that after the last shot, the plenum will fill back to the setpoint. Then when you take the gun inside, this "trapped" air will warm and the pressure will increase. For example, if it was 30F outside and 70F inside, a pressure of 2000psi would rise to over 2160psi. Thus when you take the warm gun back outside, the first shot will be at this approximate pressure. Granted, this hypothetical example is based on a pretty big temperature difference, and that's not enough to explain a 865fps -> 1000fps change. However it could be a contributing factor where there are multiple things at play.
Secondly, to produce a 1.5 inch elevation change, the velocity of the first shot would have to be about 1000fps. This is what Chairgun says using Kings at 865fps. Now if the elevation difference were only 1 inch, the velocity would only have to be 950fps...still quite a big jump. In either case, I would expect there to be a rather obvious change in the report.
Here are a couple new thoughts/questions I want to throw out:
1. Is the gun being stored with upward pressure applied to the barrel...standing in a corner or on a rack?
2. Were you shooting in the extreme cold? If so, bear in mind that after the last shot, the plenum will fill back to the setpoint. Then when you take the gun inside, this "trapped" air will warm and the pressure will increase. For example, if it was 30F outside and 70F inside, a pressure of 2000psi would rise to over 2160psi. Thus when you take the warm gun back outside, the first shot will be at this approximate pressure. Granted, this hypothetical example is based on a pretty big temperature difference, and that's not enough to explain a 865fps -> 1000fps change. However it could be a contributing factor where there are multiple things at play.
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makes since to me^^^temp difference could account for a bit along with some creep. I shoot down below the reg and store my guns that way then start with a fresh fill. I have a springer for those times i might need a spur of the moment shot.
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I had a break barrel gun that shot off on the first couple shots every time, but after it's first overhaul that phenomenon went away. I figure it was the buildup of too much lube and some of it would settle in the barrel after sitting overnight.
Maybe try pulling a single dry patch through it before shooting, just to eliminate the possibility of something in the barrel causing that first shot to be a flyer.
Maybe try pulling a single dry patch through it before shooting, just to eliminate the possibility of something in the barrel causing that first shot to be a flyer.
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I have a RWS 48 in 22 caliber that if it sets overnight same thing it takes several pellets to settle down really used to irritate me as I used to mostly to shoot squirrels around the house. I would have to take a couple of practice shoots in the basement to get it back on target as I didn't want to educate the little varmints I wanted them DEAD!
RB
RB
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This very issue is why my buddy and I changed out our regs to Huma. First shot reg creep. Both WC mark II and a compact. Issue went away.
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Thanks for you input nevrostrig >> to answer you question the gun is stored sitting on my Atlas bipod not in upright or against the wall. When I have time in the mornings will just take some shots through Chrono after sitting each night to see if there is a velocity jump. I think I might find my answer there. If so might get a HUMA reg for it I was already planning on getting a 600mm FX X-liner I pre-ordered one just waiting for FX to get them to Utah airguns. Will post my findings on first shots of the day after 24 hour sit time as I think this reg takes a long time to bleed up to higher pressure.
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Okay good luck, that sounds like a plan. I’m still skeptical that creep would cause the velocity to climb so dramatically to cause a 1.5in rise, yet show no POI change after 4 hours. The only other thing I can think of would be an extreme change in barrel harmonics but the 50 yard group you posted suggests that isn’t likely either.
Whatever the case, the chronograph will reveal how much of it is related to velocity and that will help rule in or rule out the presence of other factors. That will be useful either way.
Whatever the case, the chronograph will reveal how much of it is related to velocity and that will help rule in or rule out the presence of other factors. That will be useful either way.
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