Tuning Fx Crown 0.30

[Guest]

I recently got an FX Crown 0.30 and am wondering about tuning for power. It shoots great with JSB 44.75 pellets out to 50 yards ( 1/2 inch groups) but at 75-100 yards the pellet drop becomes significant. The max muzzle velocity I can get by adjusting the regulator (135 bar is optimal, going higher reduces FPS) and power adjuster (Max) is 830 FPS. I took off the stock to see if I could adjust the hammer spring tension but it seems to be screwed all the way in already ( gap 15 mm.) I’d also like to be able to shoot heavier slugs. Nielsen 65 grain slugs group well at 50 yards, but muzzle velocity is only about 715 fps and they lose accuracy at 75-100 yards. Is there anything else ( short of filling my tank with helium) that I could try that would increase muzzle velocity to 870-890 FPS? Thanks!

 

[TheIceman]

Well, I don't have any answers for you, but I did want to let you know I am in a similar situation. I was getting great accuracy at 50 yards, but wanted more velocity to reduce the pellet drop at longer ranges. I adjusted the hammer spring tension screw until it barely clears the power wheel cam at max setting. I upped the regulator from 140 to just under 150, and shot two mags through it. Velocity went from just under 800 fps to about 835 fps with the JSB 44.75 pellets. I had to stop there due to it getting dark. I hope to get some more range time next weekend and continue the tuning process. I will try to remember to PM you with the results. I think we are in the minority with the 30 cal Crown, and so there is not much info out there for us. I'm really interested in the hammer spring mod Ernest showed in a video recently, but haven't found any info on how to buy/make it. I am having fun learning the Crown, but I just wish I had more free time to fiddle with it. Small game season opened today here in NC, so now that will be competing for my time as well. 

 

[JamesD.]

Hi guys,

I'm no expert, & I'm sure someone will jump in here to clarify that admitted fact but: don't go messing with your regulator unless you have a tester, chronograph, or at LEAST an accurate depth gauge as a few thousandths deeper or shallower in that plenum will throw your optimized factory settings out the window.

What you want, is obtained by a few ways. One, being, deal with the drop. What's significant to you? I have all of my rifles zeroed dead nuts on at 32 yards and at 100 yards I can have 11" or more of drop from my close to 30ftlb .22 and certain pellets. Going to cast slugs is going to be like you threw a slider on purpose. Without removing that regulator & having a custom Dan Brown huge one installed, it won't happen. If you were to spend that money, then it's make NO sense not to get a longer barrel of higher quality MEANT for slugs. I believe your Crown barrel is choked, which means, it is NOT meant to shoot slugs and having any luck at all with them surprises me. 

If I were in your shoes and absolutely had to shoot slugs & pellets to 100 yards with 1" or better precision, this is what I'd do. Call TJ's Liners & get a custom longer hybrid barrel. No choke and a fairly tight bore for pellets that DO vary in size quite a bit right out of the tin. Now, I don't know .30 (basically heavy .22LR weight) optimal twist rate but I happen to know 1:16 has been an accepted standard for a long time. Take Aguila SSS 60 grainers. Neat little pills. Good luck unless you get a special 1:12 for them. Then they are something to behold. These are all very near air gun abilities, crossovers at this time in the air gun world. 

So, your choke is slowing those cast slugs down. Your limited barrel length, regulator, all settings (hammer weight, preload, TP, etc) are set for what the rifle came with on it barrel wise. If you want a regulator and a rifle that spits both pellets & slugs, you'd probably save a lot of frustration by sending it to a specialist that has the equipment, time, experience to set her up to do so. It really comes back to do I accept this rifle for what it's set for? Do I spend money to modify it by myself or another? Do I buy a different rifle that's meant to spit those 65 grain Nielsen .30's into a 1" group at 100 yards or much further & not much bigger pattern? 

You said significant drop. Gravity is unavoidable, you know that. I'm just wondering how accurately the rifle is dropping them at 100 yards and actual drop in inches. To me, drop is just part of air gunning. What kind of power is retained & accuracy is what's important to me. I don't care if I have to deal with 8-12' of drop as long as the pill is still stabilized & carrying enough energy to kill what varmint I'm aiming at. To me, that's the entire fun of air gunning. Gauging the drop & windage. If I wanted a laser, there's .223 WSSM, .204 Rugers & many other screamers that are literal lasers to near 300 yards. Air guns are NEVER going to appeal to that crowd, yet on the other hand, explain to them that shooting an airgun at 200-400 yards is a lot like them firing to 1000, maybe it would click that air guns are the best teachers of learning how to read wind & gauge drop by sight, or with modern tools (ranger, Kestrel) but don't fear $1.00-near $5.00 misses when you can get 150 almost match grade pellets for $18.99. Just rambling. Hope I helped somewhat.

 

[Guest]

What you want, is obtained by a few ways. One, being, deal with the drop. What's significant to you? I have all of my rifles zeroed dead nuts on at 32 yards and at 100 yards I can have 11" or more of drop from my close to 30ftlb .22 and certain pellets. 

You said significant drop. Gravity is unavoidable, you know that. I'm just wondering how accurately the rifle is dropping them at 100 yards and actual drop in inches. To me, drop is just part of air gunning. What kind of power is retained & accuracy is what's important to me. I don't care if I have to deal with 8-12' of drop as long as the pill is still stabilized & carrying enough energy to kill what varmint I'm aiming at. To me, that's the entire fun of air gunning. Gauging the drop & windage.

I’m not too worried about shooting anything at 100 yards ( I can hit a squirrel between the ear and the eye every time at 50 yards with a pellet that still carries 50 FPE. It then goes on to hit whatever is behind the squirrel.)

I was more interested in seeing what this rifle can do. The FX website lists max power as 82 FPE, and with a 44.75 grain pellet at 830 FPS, im getting 67, so I thought I’d try to tune it up a bit.

If I really wanted to shoot accurately at 100 yards, I could mark distances on my Viper Pro scope and use a laser rangefinder to find out exactly how far away that squirrel is. Increasing muzzle velocity would make for a flatter trajectory at longer distances. At 830 FPS, I have to adjust my scope 2 clicks between 25 and 50 yards compared to 6 clicks between 50 and 75 yards. (I did not try to adjust my scope to 100 yards, as I would have to shim it to get that much elevation.)

I’d be very interested in getting Ernest’s heavier hammer spring to enable shooting slugs with a better BC/ flatter trajectory that would carry more energy down range, but that may be more than the FX Crown was really designed for. As an alternative I’ve gotten an Airforce Texan 0.45 that should be able to maintain a flatter trajectory out to 100 yards. Watch out squirrels! 

 

[Prouzy]

From the factory, mine shoots 880fps with the 44.75. This is at 150bar regulator pressure, which is about where yours should be. Unless the hammer installed in incorrect and you have it all the way, sounds like a different issue. I would set to 150 on the reg, because we know that is about where it needs to be for stated velocities and of course fill to at least 200bar. I would then check dial settings, just by moving them into different positions, maybe they are on the incorrect reading, eg TP is actually low when it reads high? I think you need to figure this part out before bothering with a heavier spring.

 

[Guest]

I tried switching transfer port setting and hammer spring tensions which both resulted in loss of FPS. Raising regulator pressure to 150 also results in loss of FPS, which is why I though maybe increasing hammer spring tension more would help.



Another possibility is faulty o-rings. On my Armada, this resulted in a loss of 100 FPS. Anyone know I if this is common on the Crown? When I got the FX, the magazine would not fit into the slot because the brass piece stuck out too far, so I removed the barrel and reinserted it with the magazine in place. Is it possible that this prevents an o-ring from seating fully? ( I did not check the FPS with the barrel fully inserted when I first received it, but I don’t use the magazine anyway, so I would not care that it did not fit with the barrel pushed in to the point where the magazine won’t fit.)

 

[Guest]

Update for anyone else who has a similar low FPS problem with their 0.30 Crown:

As my max FPS with a 44.75 g jsb pellet was between 825-830 FPS at 135 bar regulator pressure and increasing pressure resulted in reduced FPS, I figured there was not enough hammer spring tension to keep the valve open at higher pressures. I tried adjusting the hammer spring screw, but it would not move even when I warmed it with a heat gun (moderately, as I didn’t want to melt any o-rings.) As a temporary fix, I wedged a small piece of nylon washer over the end of the hammer spring screw to take up 1.5 mm of slack.) This resulted in 870 FPS at a regulator pressure of 149 bar. I guess I should try to get the adjuster screw loose, but as I have no plans to adjust to lower power ( unless accuracy suffers at 870 FPS) for now I’ll just shoot it like this.