Tuning Impact M3 .22 700mm shooting JSB Knock Out slugs

[nerijus]

Hi,
Could you share what are your best results shooting JSB Knock outs at 100 m?
.216, .217, .218 or .216MKII?
Barrel type: STX Superior or Heavy?
Slug speed?

 

[Triggers and 4X4s]

M3 700mm STX Superior - I chucked the JSB knock outs because they are all over the place. They simply do not group (.216 and .217).

The H&N and ZAN slugs in .218 shoot extremely well in my M3.

 

[jphef]

Heavy liner, 135 bar or so on reg, getting them up to 960ish max, slow them down to 935-940. This recipe has worked the same on numerous impacts for me with the 216 and 217 originals.

 

[jps2486]

My 600 mm Crown likes .216s but not .217s. I has a superior barrel and is tuned to shoot these at 925 fps.

 

[nerijus]

My own results with JSB Knockout 25.39 gr. 217
Was shooting them with my Impact M3 .22 700mm heavy liner, carbon sleeve, harmonic tuner
I got very stable speed shots in 1020fps, 2nd Reg 130 Bar, but no accuracy at all ... Harmonic tuner did not help either.

Noticed that accuracy is much better when lowering speed. So reduced Reg2 to 120 bar, and from 975 reduced to 965 with valve. Working with Harmonic tuner got a good result shooting 50m target:

BUT at 100 m not good at all... Expecting to reach sub moa. But was far from that, like 3 inch or even more.
Will try reducing speed even more, but ran out of amo.

They say that slugs like higher speeds, but that does not seem to be so. Or is it with heavier slugs only?

 

[nerijus]

Heavy liner, 135 bar or so on reg, getting them up to 960ish max, slow them down to 935-940. This recipe has worked the same on numerous impacts for me with the 216 and 217 originals.

Were you able to get sub MOA at 100m ?

 

[jphef]

26 shots at 100 yards on one of the guns