Ghost How to improve SD & ES on Ghost HP?

[tec]

Look at the difference in impact point between the fastest and slowest of your 9fps spread in a ballistic calculator.

The accuracy required is not the same as benchrest, but most of my perfect scores (no misses) in field target matches have come from an unregulated gun with a 25fps spread.

Even for long range paper shooting like EBR, keep the spread less than 15-20fps and you're doing good. You'll get more effect on vertical impact points from wind than you will from a 20fps extreme spread.

As a whole, we airgunners get way too worked up about tight extreme spreads.

Putting some simplified math/numbers to what Cole is saying: +/- 10 ft/s velocity spread...at 50 yards the difference between a 870 ft/s pellet and a 850 ft/s pellet all else being equal is the 850 ft/s pellet got there 0.004 s slower...and dropped 0.00318" due to the slower speed....

 

[Soren Drost]

I cant wait to hear what brk says about your 190 bar reg, do let us know!. I have to say being .177 it doesn't take too much wind to push em around at 50! Seems like a good Soren Drost question? Have never played with the .177 heavies but I'd bet they do like faster speeds kinda like the. 22 mrds. From watching Aim Smalls ghost vids I recall he was saying shooting pellets fast was causing some lead formation in barrel of his ghost. Have a quick peek?!

I shoot the JSB Heavy 10.34 gn at 875-900 FPS in both the 600 mm and 711 mm barrel

 

[tec]

Here’s a pic of 13 mrds 15 - 5 shot groups top row 135 bar 950 fps , middle row 135 bar 810 fps bottom row 135 bar 810 fps no mod all shot single loader 1 right after another not paying any attention to wind @ 30 yards
View attachment 4217

Did you adj aim point or scope for bottom row?

 

[Danman]

Here’s a pic of 13 mrds 15 - 5 shot groups top row 135 bar 950 fps , middle row 135 bar 810 fps bottom row 135 bar 810 fps no mod all shot single loader 1 right after another not paying any attention to wind @ 30 yards
View attachment 4217

Hey Solo1....just curious here! Your middle row/bottom row is same pressure and speed u said, shot right after each other but there is a decent poi shift on them rows. Just wondering if that is correct?! Thanks.

 

[Solo1]

Hey Solo1....just curious here! Your middle row/bottom row is same pressure and speed u said, shot right after each other but there is a decent poi shift on them rows. Just wondering if that is correct?! Thanks.

You guys have to read everything. No mod on the bottom row

 

[tec]

I did…but I didnt know exactly what that meant. How do you account for the POI shift on the bottom row?

 

[Solo1]

I did…but I didnt know exactly what that meant. How do you account for the POI shift on the bottom row?

Take weight off end of barrel barrel moves! Its not rocket science. Every barrel made will move downward if weight is added to the end the only way i would not is if it was supported from underneath at the end.

 

[Danman]

Ahhhh I get it now no mod-erator. Sorry ... I read it through but didn't get it either. Makes sense now! Absolutely good groups though for a .177 @ 30! Keep em coming.

 

[tec]

Take weight off end of barrel barrel moves! Its not rocket science. Every barrel made will move downward if weight is added to the end the only way i would not is if it was supported from underneath at the end.

Good thing I didn't see this before I went to bed...been chewing on this all morning...simplified math...says that to raise the POI by 1/2"?...the orientation of the barrel vs the line of sight of the scope...the barrel would have to change its angle relative to the scope line of sight, which would mean that the end of the barrel is now 0.00787" higher by taking the moderator off...[assuming I understand the barrel-scope geometry correctly]
Is that reasonable?
Has anyone put a micrometer on the barrel and applied weights to see the deflection?
Do we think harmonics come into play?
More experiments to be added to my list...thanks Solo1 for the brain food ...
tc

 

[GHairgunner]

Good thing I didn't see this before I went to bed...been chewing on this all morning...simplified math...says that to raise the POI by 1/2"?...the orientation of the barrel vs the line of sight of the scope...the barrel would have to change its angle relative to the scope line of sight, which would mean that the end of the barrel is now 0.00787" higher by taking the moderator off...[assuming I understand the barrel-scope geometry correctly]
Is that reasonable?
Has anyone put a micrometer on the barrel and applied weights to see the deflection?
Do we think harmonics come into play?
More experiments to be added to my list...thanks Solo1 for the brain food ...
tc

Barrels move in 3D fashion. I found a thesis for a doctorate level engineer on the barrel tuner and its weight. HUGE formula but you could take the dimensions of the barrel weight of projectile and the speed and calculate a weight. I use this on my guns to great success. In this case yes I have measured barrel drop after mods and at best it is in the .0004 range I had to use feeler gauges. I injected the space between the barrel and the carbon fiber with a polymer and then engineered the aluminum proto barrel support the attaches to the chassis and the carbon fiber tube. The system was worth 14 points on an EBR card at 75 yards over stock. PS that was not using the front rest and wind gauges that I used in stock condition.

 

[JoeWillie]

Nice job on the Barrel Support! Interesting that it looks similar to the support on the Christmas Ghost. To be clear I’m not inferring you copied that design, just that the Engineering seems to support the general concept!
Joe

 

[GHairgunner]

Nice job on the Barrel Support! Interesting that it looks similar to the support on the Christmas Ghost. To be clear I’m not inferring you copied that design, just that the Engineering seems to support the general concept!
Joe

No problem. In the end Christmas design is a barrel tensioner, my design is based on harmonic suppression.

 

[tec]

Barrels move in 3D fashion. I found a thesis for a doctorate level engineer on the barrel tuner and its weight. HUGE formula but you could take the dimensions of the barrel weight of projectile and the speed and calculate a weight. I use this on my guns to great success. In this case yes I have measured barrel drop after mods and at best it is in the .0004 range I had to use feeler gauges. I injected the space between the barrel and the carbon fiber with a polymer and then engineered the aluminum proto barrel support the attaches to the chassis and the carbon fiber tube. The system was worth 14 points on an EBR card at 75 yards over stock. PS that was not using the front rest and wind gauges that I used in stock condition.View attachment 4246

So would you attribute Solo1's POI change due more to harmonics than actual barrel to scope angle change?
What is your opinion on the recent BRK barrel harmonics kit?
Has anyone generated before and after data?
thanks again to Solo1 and you for the brain food...haha
tc

 

[GHairgunner]

So would you attribute Solo1's POI change due more to harmonics than actual barrel to scope angle change?
What is your opinion on the recent BRK barrel harmonics kit?
Has anyone generated before and after data?
thanks again to Solo1 and you for the brain food...haha
tc

Yes, because during testing of (quite a few) tuners you can watch the groups not only change in size but it will change its way around your aim point as you change it. Simple 1/8 and 1/4 turns of the tuner doesn't change the amount of barrel droop due to weight but it does change the harmonics of the barrel and the size of your groups. Now comes another problem as small changes in speed and or temperature seem to have affects on group size. An F class shooter started making tuners that would help group size but would leave it at a given setting because he found himself taking so many sighters trying to fine tune for the day vs getting use to one setting and experience to achieve high scores. I gave one of my tuners to a teammate and he told me after a couple of months of shooting he got better results by having the tuner but screwing it on and leaving it alone netted better results then trying to do a 1/16 of a turn for more precision.

 

[tec]

yes....just thinking-guessing about the variables in that "harmonic equation", temperature, plenum pressure-shot duration, pellet mass, pellet velocity, barrel length, weight distribution on that barrel, etc...and I would imagine that unless you weight and size sort your pellets first...putting on a harmonic device ....but then shooting random pellets out of the tin is folly

 

[Solo1]

yes....just thinking-guessing about the variables in that "harmonic equation", temperature, plenum pressure-shot duration, pellet mass, pellet velocity, barrel length, weight distribution on that barrel, etc...and I would imagine that unless you weight and size sort your pellets first...putting on a harmonic device ....but then shooting random pellets out of the tin is folly

Not necessarily but yes sorting pellets really helps!