Brocock/BRK Ghost collaborative data request
- Thread starter cavedweller
- Start date
As requested...
My Ghost .20 tune has changed a bit since post #8.
I run the NSA .20/18.9s at 910-920fps.
Produced by an 18 (or maybe 19?) inch barrel.
Reg pressure of 126-128bar
Standard hammer
0.052" wire diameter spring
Power wheel on max.
Same as above pushes the JSB .20/15.89 at the same 910-920fps speeds, but with hammer tension @ "6."
Rudy, if I remember correctly, your .20 barrel is closer to full length, I want to say 22-23inches. So yours will make power better than my slightly shorter barrel.
If you're going to experiment with your .20 barrel and the NSA slugs, I'd recommend you shoot them somewhere between 880-930fps. They are accurate slower, but the BC increases with speed with these particular slugs, seeming to top out around 930fps.
You should see:
BC around 0.085 with speeds down around 860-870.
BC around 0.09-0.095 with speeds in the 880-890 range
BC around 0.1 with speeds up around 910-920.
My Ghost .20 tune has changed a bit since post #8.
I run the NSA .20/18.9s at 910-920fps.
Produced by an 18 (or maybe 19?) inch barrel.
Reg pressure of 126-128bar
Standard hammer
0.052" wire diameter spring
Power wheel on max.
Same as above pushes the JSB .20/15.89 at the same 910-920fps speeds, but with hammer tension @ "6."
Rudy, if I remember correctly, your .20 barrel is closer to full length, I want to say 22-23inches. So yours will make power better than my slightly shorter barrel.
If you're going to experiment with your .20 barrel and the NSA slugs, I'd recommend you shoot them somewhere between 880-930fps. They are accurate slower, but the BC increases with speed with these particular slugs, seeming to top out around 930fps.
You should see:
BC around 0.085 with speeds down around 860-870.
BC around 0.09-0.095 with speeds in the 880-890 range
BC around 0.1 with speeds up around 910-920.
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Thanks - super helpful - i'll fiddle with the ghost when i get back from the NC grand prix in Burlington this week.
I really would like to publish some kind of a tuning guide for the Ghost, and the Blackwolf, data matters and it certainly saves time and lead.
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Update from post 103:
.25 cal 23” HP (stock 1:17.7 poly)
Factory hammer spring
AEA 33.9 @ 905 fps, Reg 140 and PW 10, 2.5 SD / 9 ES, 50 shots on reg. Set with digital gauges. PW Max 930 fps.
I also notice at 250 bar bottle, Reg will be 141 and progressively move down to 137 by 150 bottle pressure. This doesn’t seem to effect anything just something to note.
I have to clean the barrel at 200 pellets or 1 hole groups open up to 1 inch and string by 220 shots. It takes about 10 shots to get back the original poi/accuracy, after a clean.
The barrel is stock, not polished. I just use a patch worm kit. Rifle has 750 pellets through it so far.
.25 cal 23” HP (stock 1:17.7 poly)
Factory hammer spring
AEA 33.9 @ 905 fps, Reg 140 and PW 10, 2.5 SD / 9 ES, 50 shots on reg. Set with digital gauges. PW Max 930 fps.
I also notice at 250 bar bottle, Reg will be 141 and progressively move down to 137 by 150 bottle pressure. This doesn’t seem to effect anything just something to note.
I have to clean the barrel at 200 pellets or 1 hole groups open up to 1 inch and string by 220 shots. It takes about 10 shots to get back the original poi/accuracy, after a clean.
The barrel is stock, not polished. I just use a patch worm kit. Rifle has 750 pellets through it so far.
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Similar experiences with my delta wolf. The barrel cleaning I’m beginning to suspect is due to these AEA and jts pellets. Mine loves jts 29.63 but I’m thinking of just going back to JSB to avoid the cleaning nuisance.
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