Piledriver at 70+ 1MOA or 2MOA

[skorec]

I have mentioned more times  that up to 60-70 yard I do not need any another pellets than JSB Heavy .177 or .22.  I was just finding good pellets/bullets which will be better for 70+ yd. 

It seems that after long time I finally have  found out right bullets for long distances.
The .177 Piledriver  shots 1*MOA at 5 shots group and 2*MOA at 20 shots  group.

Do you know ballistic coefficient for Piledrivers  at 270 m/s = 885 FPS  ?

[skorec]

I have found out that Piledrivers have  BC=0,82. But If  I put  value ( BC=0,082, sight high = 5,31, zero range = 70m, M velocity = 270m/s, ind Mag =24  )  into the chair gun real ballistic curve doesn’t   agree  with reality at all.  Probably because ( 12x not 8x )   points at reticle  at my  Nicko Stirling 6-24x56 Neghtater  are not one MilDot but two  MilDot

https://zbrane.subrt.cz/puskohled-nikko-stirling-6-24x56-nighteater/

I have draw myself reticle.

[thelast88]

Nikko Stirling are 16x MD calibrated, not 12 or 8x...

[Taso1000]

Skorec,

Have you changed the ballistic profile?  The default GA is for diabolo waisted pellets.  Maybe the RA4 profile will match the Piledriver shape better? 

Taso

[skorec]

Skorec,

Have you changed the ballistic profile?  The default GA is for diabolo waisted pellets.  Maybe the RA4 profile will match the Piledriver shape better? 

Taso

No I haven`t . Where I can do it ?

[Taso1000]

Here's a screen shot to where the drop down is:

Taso

[skorec]

Thanks a lot. Anfortunately chairgan stiil show me 42m at up Mildot 4 but physical reality is at up Mildot 2. 

[Ribbonstone]

Direct measurement (getting velocity at two know distances) at short range (1yard and 30 yards) came up with .079.  Typically, pellet BC changes with range, and is likely to be bit lower at short range.

Will mention, that in trying a whole lot of .177's (think last count was 14 rifles), only managed accuracy I could live with with one....and that one was not a power house PCP.   But it managed  about 1.4MOA.

If I might suggest a test....it's going to be "icky"....try catching pellets that exit a critter on a back stop that captures accurate pellet holes.   I used a thawed whole chicken, cavity stuffed with some hot-dogs, and wrapped in a double layer or t-shirt as the target (about 25 yards) and a chunk of dry wall as the "exit catcher".

What I found, both by the exit holes in the dry wall and a dissection of the store-bought chicken, was that the long pellets tend to tumble shortly after meat impact.



This is a good news/bad news situation.   Lighter weight pellets, like the 13.5gr. JSB's, tend to penetrate deeper (which would be good for larger critters), but the .21gr. PileDrivers tend to dump more energy/faster that you'd expect (like more gapping  exit holes in little critters like squirrels).

This isn't too "freakish"....lots of military FMJ bullets tend to fly though air straight and stable, but go arse-over-teakettle once they meet firm resistance.

[Taso1000]

Skorec,

Are you sure you have all your units in metric in Chairgun?  Do you have an owners manual of your riflescope to share?  Maybe we can find how the dots relate and at what power?

Taso

[skorec]

It is low cost riflescope from e-bay. I have not user manual . Here are values.
Real POI for 42m is near point/dot 2 -  see the picture.

[Taso1000]

I honestly don't know how long the distances per dot in your reticle is but you could always get a meter stick, set it out at 50 or 100 meters and find at which magnification your dots match up.

Taso

[Taso1000]

There is one reticle manual on the Nikko Stirling website but it's not for your scope.  They're using 10 power for a 6-24x50 scope.

Taso

[skorec]

I have found out the problem. cal Mag is 20 for my riflescope -  seams to be 20.

[skorec]

Taso thanks a lot.

Why the dot POI is not highest at 40m but at 25m ?

[skorec]

Just I want to add info that I am shooting 4,46mm not 4,50mm  Piledriver from my choked LW 15x605mm TR 1:17,7 barrel.

[Taso1000]

Taso thanks a lot.

Why the dot POI is not highest at 40m but at 25m ?

Maybe because the scope line of sight is higher than the barrel?  You can show the line of sight for the scope in the graph.  There's an option to display it.

Taso

[skorec]

OK and is it  possible to show ballistic curve reach at line of sight/laser line   ?

[skorec]

OK and is it  possible to show ballistic curve reach at line of sight/laser line   ?

[aPpYe]

How well do you do benchrested with the piledrivers at 50 yards?  I remember doing about 2-3 inches at that distance.  Not very well.  There was quite a bit of variation between the pellets, some with Xtra material on the skirt, some with flattened heads:



...Same thing with the 15.x grain snipers, and they grouped even worse:


I have been shooting the JSB Beast (16.2gr) ever since.  They group nice and tight for me...

[skorec]

Ten shoots of Piledrivers 4,46mm   from 272m/s( 3000 PSI ) to 266m/s( 2600 PSI ) at 77 yd. I am just thinking to ad Huma regulator  adjusted  to 180bar/2600PSI. Also I will need to solve some better/clamp  gun rest. I believe I stay at 1MOA very similar as with JSB heawy at 295m/s. With the JSB Monster REDESIGNED I am 1,5-2,5  MOA

I had 10 MOA grouping with old style JSB Beast and JSB Monster. When they produce REDESIGNED Beast I will  test them for sure.