Hi STO , I recently bought a FX Crown in .22 and , well , was a bit disapointed by the accuracy. Maybe the gun needs some break-in, I shot just 4 magazines . Despite my problem by changing the barrel to a .25 ,( see my topic " FX Crown problems" ) I think this gun has a lot of potential once the right adjustments are found. By the way , could you tell me the values you set on your FX , reg pressure and power wheel for .22 an .25.Thanks.
Mike
Funny thing, my .22 Crown had leading problems when I first got it. After less than 100 rounds, there would be a lot of lead in the bore and accuracy would be substantially impaired. I did two things to it, and I'm not sure which actually helped or if both did, but afterward it shot tight groups and never needs cleaning. The first thing is I hit it with JB Bore Paste, not once, but twice. The first time seemed to help so I did it again, but before I could properly test/quantify I found myself down a rabbit hole of moderator design. When I came out the other side, I'd fired hundreds (maybe thousands, memory is fuzzy but it was a LOT) of rounds without cleaning or paying any note to the accuracy. After that I shot a little, expecting a mess, but instead found the gun was MOA at 100 yards. So I didn't touch it, didn't clean it, and haven't since. It is still laser accurate.
The .30 I actually got to play with moderators specifically, so it swallowed hundreds of rounds before I even put a scope on it. When I did, it was accurate but groups seemed to wander a bit. Turns out the tubular bolt and muzzle brake weren't sufficiently snug and so the shroud was able to walk around a little.
I saw your thread earlier today. That bore seems a bit snug for .25, but what do I know eh? It should certainly clear either way. I'm guessing it backed off a bit. I've seen one other account of someone whose muzzle brake loosened up and it took a couple hits before he figured it out. Long before you start striking the brake, the close proximity to the pellet (air effects increase exponentially with reduced tolerance) and the brake not to mention the shroud no longer being correctly centered will start costing you accuracy in a big way. Without having tensioned your inner barrel and tightened your muzzle brake, you'll really have no idea what the barrel is capable of if that makes sense.
As far as settings go, my .22 and .30 are set at 135 and 150 bar respectively. HST numbers are meaningless because the actual internal adjustment of the spring stop screw is different between guns, not to mention the spring coefficients themselves. You want to tune for the low-power side of the performance knee, irrespective of your pressure. That is to say set yourself up with whatever plenum pressure you want, and then go into the action and adjust the HST up to more than you'll need. For safety of the valve, I prefer to start low and go high, but start with the minimum HST setting on the wheel and start clicking up by one every couple of shots. (chrono all of this and write all your settings down) As you increase HST, you'll increase in power..... to a point. Then you'll plateau and start going back down again. You want an HST setting which is BEFORE (lower) than that plateau. That is what I mean by tuning for the low side of the knee, you want the hammer strike to be just slightly less than what would yield maximum power, assuming you're tuning for efficiency and accuracy anyway. You can also click down for even lower velocities if you want to use less air and what have you, lots of guns out there like the Thomas rifles don't have user adjustable regs and so work exclusively on the low-hammer-force side of that power peak. So you clearly can get good accuracy further down the downhill side, but the idea of being JUST BARELY below the plateau is that you're on a part of the power curve where the slope is less steep. This way, if your reg varies by a few bar up or down your velocity delta is minimal.
I hope that helped explain everything.
"I think this gun has a lot of potential"
I've said it before, and I'll say it again: it is just my humble opinion that the FX Crown is the best production airgun out there right now. The ease with which it can be tuned and tweaked, plus its air capacity and overall modularity, make it fantastic. It also has a real elegance to the engineering inside it. Everything should be as simple as it can be, and not one bit simpler. To get the features, the Crown runs right on the ragged edge of too complicated, but (IMO) the Impact steps over it into the realm of too fiddly and complicated to be elegant. And even if you don't like the FX barrel liner system, which some people don't, it is no harder to rebarrel than any other gun: just go buy your LW or CZ or TJ or Bartlein or whoever barrel blank, and lathe it to fit along with your own tophat. It is really not any different than any other airgun in that regard. The core of it is an action which is both relatively simple and elegant, and stupid easy to work on.
Just my 2c.
