Strelok Pro question

Since velocity is a KNOWN value you should have used that. BC is a calculated (even changing) value. Never used Pro, but for certain I would always enter known values as whatever they are.

My question is if you've already entered the correct velocity and PRO is not quite right, what do you adjust? Can't be velocity that's the problem,,, has to be something else, right?

I believe that for pellets the drag should be "G1", plus the known velocity. It's also important to get the scope height right. According to Chairgun, that dimension is to be taken from the muzzle, not simply from the center of the scope to the center of the barrel near the breach. I know that this is not Chairgun, but maybe same would apply?



https://www.youtube.com/watch?v=BqjB6vl6dEI



Then there is this from a previous AGN thread....which blows that outta the water.

Scope height and how to calculate? - Airgun Nation

mike

I went out tonight and used a FX chronograph to check the velocity of my 25gr 25cal JSB Kings out of my FX Impact. I zeroed at 30 yards and was 3MOA low at 103 yards. I trued the app on BC instead of velocity (0.032). When I went into the app I saw I was using multi BC (only 1 input) and the RA4 drag function. My question is....should I have changed the velocity or the BC?

Click to expand...

From what I've seen you want to use GA for drag function, RA4 is for 22LR according to the app. Here are some good videos on how to us Strelok Pro:



https://www.youtube.com/watch?v=5jgVcfH0kNU





https://www.youtube.com/watch?v=r_mppgSoSyI





https://www.youtube.com/watch?v=kPvwGV4ye-I





There is also lots of resources at the website

http://www.strelokpro.online/StrelokPro/ios/default.asp

I believe that for pellets the drag should be "G1", plus the known velocity. It's also important to get the scope height right. According to Chairgun, that dimension is to be taken from the muzzle, not simply from the center of the scope to the center of the barrel near the breach. I know that this is not Chairgun, but maybe same would apply?







https://www.youtube.com/watch?v=BqjB6vl6dEI







Then there is this from a previous AGN thread....which blows that outta the water.

Scope height and how to calculate? - Airgun Nation

mike

Click to expand...

The video shows a pretty precise way to measure that however measuring at the optic is usually easier and unless the target as used in the video is closer to the muzzle than the optic is mounted on the rifle from the muzzle the error in his method will be greater than the error of just measuring at the optic.

In either case the error is probably on the order of 1% at 100 ft. Bottom line is either way works just fine.

Now if you think about it sight heights are usually on the order of 40 or 50 mm. An error of 1% of that is .4 or 5 mm. The math can be done to describe how much that would affect the accuracy of the ballistics calculations but there's no point. That kind of error gets lost in pellet differences, temperature differences, wind differences ranging errors things like that.

OldCrow --=--

Thanks for the information on the scope height. It was a little confusing considering the difference between the two entities.

I did a small search to find the proper BC settings using the designations given within the Strelok program. Located here: RSI - Exterior Ballistic Coefficients (shootingsoftware.com)

It appears to me that using pellets, perhaps the setting should be 'GL', which is the same as 'G1' but for < 1,400FPS. I also figure that the slug setting should be 'RA4', again, the same as 'G1' but for a .22 LR at < 1,400FPS. Of course, using a larger caliber may not be as congenial and a different designation might be needed? However, since both the above have slower velocities, they should be good to go. 

Haven't had time to verify this in the field but wanted to lay it out here for any input.

mike