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FX Crown Question

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lamarkeiko

Member
Jun 22, 2017
129
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Oregon, United States
I have an FX Crown I purchased new in May 2018, SN FXC 181098. I am interested in doing some upgrades for increasing power for shooting slugs.

I've looked at several components for doing this, such as Huma Regulator, hammer weights, Huma pellet probe and hammer springs. It seems inorder to order some replacements, I need to know what generation or MK model my Crown is, which I do not know. Right now I am getting about 850 fps with NSA 33.5 grain 25 cal slugs at 145 bar hammer max. Would like to be able to get 900+ fps. I have installed a superior liner and also a Huma dual transfer port, which didn't change velocity at all. Help requested.
 
Lamarkeiko;

This sounds counter intuitive, but try lowering your regulator pressure. I read this on Airgun Nation a couple of months ago, tried it and it worked. With a 600mm barrel, regulator at 150 bar JSB 25.39gr pellets were clocking 986 fps. Lowering the regulator to 130 bars increased the velocity to 1015 fps. Using H&N 34gr slugs velocities went from 845 fps to 885 fps. With my gun and set up, I think to get more velocity will require a heavier hammer and hammer spring to take advantage of higher regulator pressures.

George
 
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Without increasing the plenum size, you are pretty much limited with what you have. The optimum reg pressure appears to be about 135 bar. Going higher destroys efficiency and your shot count. If efficiency and shot count is not a concern, you can increase your speed with a heavier hammer and a higher reg pressure, but you need to do both.
 
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Without increasing the plenum size, you are pretty much limited with what you have. The optimum reg pressure appears to be about 135 bar. Going higher destroys efficiency and your shot count. If efficiency and shot count is not a concern, you can increase your speed with a heavier hammer and a higher reg pressure, but you need to do both.
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Looking at my records from testing, 140 bar was about my most efficient reg pressure. I got about a 20 fps velocity increase from 135 bar to 140, but jumping up to 145 bar only increased velocity by about 5 fps. I think my hammer weight or spring need to be increased to be able to get more velocity. I have done pretty extinsive testing/tuning from 130 bar up to 145 bar with various pellets and slugs for velocity and accuracy. Most every thing I've read says you need more velocity to get the best accuracy for slugs, so that's my goal.

I would like to install a new Huma regulator, along with more hammer weight or spring, and have found where I can purchase, but there is a choice between Generation 1 or 2 for ordering the regulator, which I don't know what my crown is. Is Generation 1 and 2 the same as MKI and MKII? I believe my Crown is MKI but I don't know about the Generation.
 
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I called FX USA today, and they told me I have a Generation 1 Crown. I had heard the terms MKI, MKII, Generation 1 and Generation 2 for the Crown, so I didn't know if there were 4 different versions of the Crown. I was told that MKI and Generation 1 are the same, along with MKII being the same as Generation 2.

Now my question is, I would like to shoot with more regulator pressure, so should I have a heavier hammer or a stronger hammer spring? I see I can purchase a heavier hammer on EBay for only $18, but I'm not sure where to get a heaver hammer spring.
 
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I made an order from Huma-Air for that Crown hammer spring, along with the Crown High flow pin probe, which should match up with the Huma-Air dual transfer port that I've already installed. Before I ordered from Huma-Air in the Netherlands, I did a lot of Google searching, and could not find where I could order these items in the US, except Trenier which only carried the high flow pin probe. Hopefully it won't take too long to receive.
 
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I took my Crown out this morning with the crony and shot a string of shots with 145 bar on regulator and hammer A before installing the new Huma high flow pin probe. I was shooting .25 JSB MKII pellets. My average velocity was 850 fps with ES of 3.

I installed the new high flow pin probe, and without making any other changes, shot another string with an average velocity of 867 fps and ES 3. I did a 2nd string and got an average this time of 869 fps and ES 4.

That's 17-19 fps increase in velocity by just installing the Huma-Air high flow pin probe. I'm happy with that. I'll change out the new heavier hammer spring next and do some tuning at various regulator pressures and hammer settings to see what improvements I may get in more velocity and hopefully accuracy. I don't plan on setting the regulator over 160 bar.


 
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Venon said:
Hi everyone! How capable is Crown MK1 with a stock 500 mm barrel liner in shooting slugs? is it justifiable? I would appreciate it if you would share your thoughts on this. Thank you
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Doable, but not at the speeds the mk2 can push them due to better valve design and larger plenum. You would also probably need to do some mods like hammer spring, transfer port and pin probe to help increase the air flow a bit.
 
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madeintheuk said:
Doable, but not at the speeds the mk2 can push them due to better valve design and larger plenum. You would also probably need to do some mods like hammer spring, transfer port and pin probe to help increase the air flow a bit.
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Yeah if he can find a 500mm slug A liner or superior I suppose. I've shot the 17.5gr or 20gr NSA lots with the 500mm slug liner mentioned and it was fantastic at normal power 30-40fpe. Had a bark though (no moderator) Assuming you're talking about .22
 
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Venon said:
Hi everyone! How capable is Crown MK1 with a stock 500 mm barrel liner in shooting slugs? is it justifiable? I would appreciate it if you would share your thoughts on this. Thank you
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Plenty. I shoot 25gr .218 slugs in my mk1 @50fpe

Using 7gm hammer weight, 150bar, and custom ports on barrel/TP
 
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