FX Crown slugs issues

[aldea6]

Hello ,

I put a .22 superlight barrel kit fitted with a superior heavy liner to shoot some slugswith my Crown. Settings are 130 bar on the reg , Max on the hammer tension spring wheel and .25 / 30 on the transfert port . Slugs are FX .22 , JSB KnockOut 25gr and H&N 21 gr. I cannot achieve speed higher than 830ft/s.

The barrel is also fitted with a Huma dual transfert port. The gun was zeroed with a "normal" pellet liner to shoot JSB 18gr at 860 ft/s , transfert port on .177/.22 . It shoots very accurately. Slugs shot with the above settings were 10 inches below the aiming point ; this was probably due to the lower velocity , but how to increase it ? Shooting JSB 18gr pellets through this heavy liner with the settings used for the slugs gave me same results : about 8 inches below bullseye , but with a speed of 930 ft/s .

I really don't understand these results and what to do do fix that problem . Does it come from the liner , the lack of power or what?

I anybody could give me his opinion , he'll be welcome.

Mike.

 

[Ghostranger169]

My unmodified .22 Crown MK1 with 700mm Super Heavy(OR Superior liner) liner will shoot KnockOuts and H&N 25g slugs up to 920 fps.

Both slugs are very accurate at MUUCH lower speeds(825- 890) out of 700mm, 600mm, 500mm, or 380mm Superior barrels as well, so you don't HAVE to max everything out.

A good procedure to max out a Crown is: Make sure your HS pretension screw is close to maxed out, HS wheel on Max, and . Then start raising the reg pressure 5 to 10 bar at a time, then shoot over chronograph. Repeat this until fps starts getting lower, then lower reg pressure 5 or 10 bars. This should be close to max for your Crown. Should be 140 to 150 bar for the MK1.

 

[aldea6]

Thanks Ghostranger16 , I'm going to do the things in a more methodic way....

 

[jonjo]

Your point of impact being low could well be due to liner position. With your set up are you able to rotate your liner to different positions within the barrel. If you can then suggest you index your liner to give the highest point of impact. A lot has been written on here about barrel indexing and should be done to those rifles that are able. If done correctly should give increased accuracy at varying distances i.e. neither shooting off to one side at varying distances. Hope you get it sorted.

 

[aldea6]

I haven't tought at this , but it could be the cause of a low POI . I'll check this tomorrow.

Thanks jonjo.