With the transfer port on Low and the Power Wheel on MIN, what is the lowest velocity achievable with the .22cal 500mm barreled MKII Crown with 18gr pellets? Is it still accurate at that velocity?
FX Crown MKII .22cal velocity question
- Thread starter Corvid_hunter
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Would depend what the reg is set to and where the set screw for HST preload. You're only mentioning 2 of the 4 parameters.
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Glem is correct you need to turn the gun over and read the Reg pressure. I know of three crown mk2 all have different reg pressure one is set at 105, mines at 110 and the 700mm barrel gun is set at a hair over 140gbar. These are all .25 cal.
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Unscientific response to your question, and the closest I could get to your specified set-up was with a 600mm barrel (so maybe subtract ~30 fps for a 500 mm barrel?)
Shot string with gun at Min HS and Lo TP gave this:
Shot count: 14
Low: 503
Hi: 529
Avg: 520
Spread: 26
STD Dev: 9.5
508
515
503
520
506
524
524
524
527
510
529
529
529
529
I kind of got bored waiting for the 18.1 pellet to get to the 25 yard target!
I normally shoot this Crown with the TP on Med and the HS on MAX. On those settings I get a real small ES and SD, and with the 18.1's a muzzle velocity averaging 882 fps. The reg on this gun is set to 120 bar. I don't recall that I have 'tuned' it much, other than checking velocities at different TP and HS settings, and seeing if I got the number I wanted, and then testing for accuracy.
Accuracy difference apparent even at only 25 yards, likely due to the larger ES of muzzle velocities at Low/Min. Possibly not enough HS pre-tension to open the valve consistently. Top group is 10 shots at Low/Min with no called flyers on my part. Bottom group is 10 shots immediately following, with gun set at Med/Max. Shot #7 at 4:00 really opened up this group. Pellets are unsorted. Wind - light breeze from about 2:00. Temp about 85 deg F.
Won't say that you can't get accuracy with a Crown at Lo/Min at 500fps or under, but you would likely have to reduce the reg pressure to get it.
Shot string with gun at Min HS and Lo TP gave this:
Shot count: 14
Low: 503
Hi: 529
Avg: 520
Spread: 26
STD Dev: 9.5
508
515
503
520
506
524
524
524
527
510
529
529
529
529
I kind of got bored waiting for the 18.1 pellet to get to the 25 yard target!
I normally shoot this Crown with the TP on Med and the HS on MAX. On those settings I get a real small ES and SD, and with the 18.1's a muzzle velocity averaging 882 fps. The reg on this gun is set to 120 bar. I don't recall that I have 'tuned' it much, other than checking velocities at different TP and HS settings, and seeing if I got the number I wanted, and then testing for accuracy.
Accuracy difference apparent even at only 25 yards, likely due to the larger ES of muzzle velocities at Low/Min. Possibly not enough HS pre-tension to open the valve consistently. Top group is 10 shots at Low/Min with no called flyers on my part. Bottom group is 10 shots immediately following, with gun set at Med/Max. Shot #7 at 4:00 really opened up this group. Pellets are unsorted. Wind - light breeze from about 2:00. Temp about 85 deg F.
Won't say that you can't get accuracy with a Crown at Lo/Min at 500fps or under, but you would likely have to reduce the reg pressure to get it.
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You can get it down to 400 FPS if you really want to.
my reg is at 140 bars and HS at minim with preload at minimum the 7.4 grain pellet is around 550fps. With HS on high I can get the 12.5 grain slugs to fly at 920. Also with low HS and high reg it’s Uber quiet but ES is a bit bigger but still accurate for 30 yards and under. High reg is the way to go, it would be near impossible to get low enough reg pressure to shoot that low, I’ve tried. 80 bars is the very minimum reg pressure FX officially support and I was shooting 7.4 grain in the 800fps range with minimum Hs.
my reg is at 140 bars and HS at minim with preload at minimum the 7.4 grain pellet is around 550fps. With HS on high I can get the 12.5 grain slugs to fly at 920. Also with low HS and high reg it’s Uber quiet but ES is a bit bigger but still accurate for 30 yards and under. High reg is the way to go, it would be near impossible to get low enough reg pressure to shoot that low, I’ve tried. 80 bars is the very minimum reg pressure FX officially support and I was shooting 7.4 grain in the 800fps range with minimum Hs.
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