This is a guest blog from reader Vana2, whose real name is Hank. Today he tells us the story of his new-to-him FX Crown precharged pneumatic (PCP) air rifle.
If you’d like to write a guest post for this blog, please email me at email@example.com.
Take it away, Hank.
My FX Crown Story
by Hank Vana2
This report covers:
- Why a Guest Blog on the FX Crown?
- My new Crown
- Initial setup
- Pellet selection
- Getting into the power band
- Initial balance
- The factory tune
- Where are we now
- A more conventional target
Why a Guest Blog on the FX Crown?
I would like to tell you about the FX Crown MK2 that I have and how I came to have it. I was not looking for another airgun as I have a couple that cover the “general shooter, hunter, plinker, pester” category that I place the Crown in, but this one was begging to be rescued.
It seems that the original owner had watched YouTube videos of shooting pigeons at 150 yards and decided that having an FX PCP would make that easy. The Impact he wanted was not available so he bought a Crown MK2. When the Crown did not live up to expectations he was looking to be rid of it. After publicly voicing his frustrations and generally bad-mouthing the FX and all their products there was little interest in his airgun. In fact a couple of friends tried to warn me that the rifle was a lemon and that I should walk away from it.
I tried to explain to the owner that the issues he encountered were easy to fix but he was adamant: PCPs were just a bunch of high-priced hype and he was done with them. In the end I traded for a lightly used (and slightly misused) .22 caliber FX Crown MK2 with a 500 mm barrel and a nice walnut stock. He was very happy with the deal and so was I.
I’m not going to get into all of the configurations of the FX Crown or into a detailed review of this airgun as there is lots of information and professional reviews already available on the net.
What I would like to do is share the steps I took to restore this .22 caliber FX Crown MK2 to its normal working state. The images included are of my working targets (that were rescued from the trash bin); nothing was specifically prepared for this guest blog so you are seeing my “raw” data.
My new Crown
The advantage of the Crown is that the power adjustments are easily accessible; the disadvantage of the Crown is that adjustments are easily accessible — and people can’t leave well enough alone so they turn up everything to “Full Power”.
Before taking possession of the Crown I confirmed that it was holding air and there was no obvious damage to the rifle itself. Exceeding the manufacturer’s maximum recommended pressures is a sure way to damage the seals, so air leaks are an indicator that the rifle was abused. I had fired a dozen shots so I knew that in spite of sounding strange it was working. All looked in order and, in addition to the rifle, all the usual paperwork and stuff was included in the gun case.
After a hardware check and pulling a patch through the barrel a more detailed inspection showed that transfer port, hammer spring and regulator were set to MAXIMUM. The gun was very loud, inconsistent and shooting at a much lower velocity than would be expected for a 160 bar regulator setting.
The Crown has 3 externally adjustable settings – the hammer spring (HS) dial; the transfer port; the regulator (with an Allen key) and one internal adjustment, the hammer spring pre-tension which requires the stock to be removed.
I could hear and see that the Crown was way out of tune when I first shot it. To get to a starting point where I could actually start to move forward with a tune I reduced the regulator setting to 100 bar and checked the hammer spring wheel tension.
It turned out that the hammer spring wheel had been messed with — the pre-tension adjustment screw had been backed out to the point that only a couple of detents on the CAM wheel were effective. To correct that I used an Allen key to tighten the pre-tension adjustment screw and bring the CAM to the point where, when turning the wheel, each detent actually changed the tension on the hammer spring. The neutral setting on the CAM wheel is very low but it’s a starting point and later I would dial in the hammer spring pre-tension to give me a useful range of adjustment for my tuning.
The next task was to decide what I was going to set the rifle up for and to select the pellet I wanted to shoot. In my humble opinion, the Crown, with a regular thumbhole stock and the 500 mm barrel, is ideal as an off-hand plinking rifle, which suited me fine.
With a fixed power airgun like a springer, single-stroke pneumatic or a factory set PCP (without ready access to the adjustments) you go through the routine of finding the “golden pellet(s)” that best suits the power and harmonics of the airgun.
With an adjustable PCP you can select a suitable pellet and (can usually) tune the airgun to shoot that pellet well.
I chose a pellet weight to suit the energy level I wanted to work with for the application in mind — in this case: a general shooter, hunter, plinker, and pester. I’m looking for 30-ish foot pounds in a quiet shooter with a good shot count. Considering the 500 mm barrel, the JSB 15.8-grain (both the Hades and the Exact Jumbo) pellets are a good match. With a 600 mm barrel I would have gone with the JSB Exact Jumbo Heavy 18.13-grain pellet and I might decide to go there anyway — the 500 mm Crown has plenty of power to tap into and I have a good supply of the 18.13 pellets.
Getting into the power band
In .22 caliber PCPs that have the power, most barrels are designed to work well with a velocity in the 880-900 feet per second (fps) range so I want to adjust the regulator to give me a velocity that is about 50 fps over that at the MAX hammer spring setting. This would give me a range of settings to test at mid hammer spring settings.
If the hammer force and plenum (the area between the regulator and the valve) pressure are out of balance the airgun will perform poorly. In theory, the ideal setting on the power band is 3 to 5 percent below the flat part of the power curve with a sufficiently high pressure to achieve the desired velocity.
A brief explanation: the hammer force (weight and spring tension) has to overcome the pressure behind the valve to open it wide enough and long enough to allow a pulse of air to propel the pellet out of the barrel. Insufficient hammer force or excessive pressure will upset the balance – this was exactly what my Crown was suffering from.
[Editor’s note: Pay attention to what Hank is saying here. This is how you set up a PCP. You don’t look for the most power. You look for a happy balance of power, accuracy and shot count.]
Usually, re-tuning a PCP to a different pellet is a minor thing because you are nine-tenths of the way there with the factory tune. In this case, though, the settings were so far out of balance that I had to start over from scratch.
I had (deliberately) gone low by choosing 100-bar reg pressure and a neutral hammer spring setting so I could find the initial balance between the two.
I’m setting the Crown up so that the velocities for hammer spring settings in the middle of the adjustment range will be in the preferred 880-900 feet per second (fps) range. This gives me some latitude to look around and try different velocities.
I started by shooting over the chronograph, increasing the regulator pressure until the velocities stopped increasing (indicating that the hammer spring was set too weak) then I would increase the hammer spring pre-tension a bit and continue shooting and monitoring the velocities. Through incremental adjustments and testing I found a place where, with 115 bar on the reg setting and the MAX hammer spring setting gave me the 950 fps that I wanted to work with.
I then tested all the detents on the hammer spring adjustment wheel to confirm that, from MIN to MAX, each showed a change in velocity. All was fine, indicating I had a good initial balance.
The factory tune
Efforts up to now have been to bring the Crown into a known good state. Now it’s a matter of trying different hammer spring settings looking for good groups and then fine-tuning the regulator pressure to optimize pellet stability and air usage.
This is the stage where I might try different brands or weights of pellets to see if the airgun had a preference. Typically people will test several pellets in searching for the optimum match. I had decided to focus on the JSB 15.89 as I was confident that the tuning would go well. If not, there was always “Plan B” — the JSB 18.13 pellets. The Crown has a variable transfer port (LOW, MEDIUM, HIGH) so I shot a card at the HIGH (shown below) and MEDIUM settings as well.
I feel that inconsistencies in pellet/barrel performance and tune don’t show up clearly at close range and that shooting a long range introduces variables (the shooter being the main one LOL!) that negatively influence the testing. I do my PCP testing at 40 yards which I feel is far enough to show tuning issues without being too far so that inconsistencies in shooting overwhelm the details.
Getting into the actual tuning, I did a quick sight-in at the mid-hammer spring setting to get on paper and then shot a card using different hammer spring settings. In addition to the point of impact rising, I expected to see the group size go from open to tight to open again as the velocities go from too low to too high.
Here I’m testing from MIN to MAX across the hammer spring adjustment wheel. As expected 3 & 4 showed good pellet flight (I pulled that flier on 4) the groups for 5 & MAX look good but they are shooting too hot and showing some spiraling – they all landed together at 12:00 o’clock but changes in distance would change the point of impact.
Once I’ve identified the hammer spring settings that shoot well I shoot a number of targets to determine which is best. At this point I’m monitoring velocities, watching for pellet stability and overall consistency.
Here I’m testing various settings more closely. The “H5” in my crib note means transfer port HIGH and hammer spring 5. And 946 f.p.s. is the velocity at those settings. I also tested some MEDIUM transfer port settings. I’m currently using H and C (902 fps) on this tune.
These targets are usually a mess… a bunch of aim-points and with holes peppered all over them. I’ll pick an aim-point and shoot enough pellets to decide if I want to continue testing that setting or abandon it to try something else.
When I find a setting or two that show promise I’ll shoot a series of more formal targets to determine the one I’m going to stick with.
Just a note, my Crown has the earlier hammer spring wheel with a double-lobed CAM. One side is numbered and the other has alpha characters. Being slightly offset, the two CAMs complement each other – the velocity of “A” is in-between that of “4” and “5”. A bit confusing until you get used to it, the hammer spring dial on the new Crowns are all numeric.
Once I’m happy with the tune I’ll optimize the air usage. Ideally the volume of high pressure air in the barrel is just enough to launch the pellet at the desired velocity. Besides reducing the shot count per fill, excessive air causes a loud report and can destabilize the pellet.
I do this adjustment mostly by ear though I monitor the adjustments with a chronograph. By making small reductions to the hammer spring pre-load and/or regulator pressure I can optimize the air usage. As the adjustments are made the sharpness of the muzzle blast will diminish with only a slight loss in velocity. A sudden drop in velocity means that I’ve reduced too much and need to add a bit back.
The best combination of HS and regulator pressure is what I call a “factory tune” level. The airgun is shooting well; it’s accurate, consistent and efficient in its air usage.
Most people stop here and call it done. Nothing wrong with that but there’s still some tweaking that can be done if desired.
Where are we now?
Now that I’m at a factory tune I’m treating my Crown just like a new airgun, breaking it in getting and used to it.
Stats for this tune (15.89 pellets) are: Average= 902; High= 907; Low= 891; Spread= 16; SD= 5.8; Energy= 28.7 foot pounds.
I’ve noticed that with the large, rounded forearm and a high scope that I have to be particularly aware about canting the rifle. Still, on average, I’m keeping my shots within 3/16ths of an inch of my aim point at 40 yards — and I’m happy with that.
This is one of my (many) practice targets. I like to shoot a session (25 pellets at 40 yards) and measure the distance (the Delta) from my point of aim (POA) to the point of impact (POI). I use the session average as an indicator of how accurate I was.
Once my Crown is broken in I’ll likely check the barrel indexing, polish it with some JB Bore paste and tweak the tune to see how low I can get the extreme spread (ES) for a 25 shot string. These bench rifle tweaks aren’t necessary unless you are shooting in competition for money but they are fun to do – kinda like sorting pellets, if you get my drift.
Being a working airgun I’ll be adding a sling and refinishing the stock to suit my preferences.
A more conventional target
I usually don’t bench shoot a PCP at under 40 yards unless I’m sighting in at the optimum far zero range. With the talk about the Pyramyd Air’s 25 Yard Challenge I thought – what the heck — there was a card on the 25 yard butt so I shot a couple of targets just to see what I’d get.
I still happened to have it so I included the card for reference. The dimensions are for the center-to-center group size.
To interpret the target… the near zero on the FX Crown is 21 yards. Since I was shooting groups and didn’t want to blow away my aim point I just held dead-on and didn’t bother to compensate for the pellet rise or the wind blowing from right to left.
All and all, I’m very pleased with my trade. It took all morning to set everything right but the FX Crown is now shooting well. Being light weight and nicely balanced it is fast becoming a favorite.
There are deals to be had. Hope that sharing my experience with my FX Crown is of interest.