dope dilemma

[paul73]

so, i was finally able to make a 300yds dope for my cz457 using sk long range match rounds.
used a chrono as well to confirm data - wish i measured more than 5 shots, dunno what the heck got into me to only do 5 - but it got to 1112 fps, es 48 sd16 - not exactly a stellar match data, slowest was 1092, fastest 1140.

so, i have 0 reason to suspect strelok pro to be incapable of calculations, but, it gets puzzling.

rifle is set on 50yds zero, i did not go back to 50 to re-confirm it, but, it was zeroed for 50.
factual measured drop in mrad at a 100yds is 1.6, factual measured at 300 ended up to be 13.

if i load official SK LR match data in strelok - 1106fps, 0.1760 BC - then the table it produces gives me
1.8mrad at a 100, 12.7mrad at 300.

i suspect their posted G1 BC od 0.176 is bullshit, as looking at norma data it seems to be from 0.13 to 0.15

if i use BC correction feature in strelok for 300 drop - it gives me a 0.156 BC that may be there, but, that still has 100 drop at 1.8, which is a lot off from the factual 1.6mrad.

no matter what i tried so far with source parameters, i cannot get to a table printout that would reflect the factual data i have - the 1.6 and 13 mrad drops.

with all other guns i never had such an issue, it is rather odd. i wonder if it is a 22lr specific thing? but, why would it be?

 

[paul73]

Here how sk long range shows on a , I think, 8” plate, aimed at center.

 

[Road_Clam]

I was in a very similar situation when i was trying to fabricate dope calcs for my Sharps 45-70 with a 5x micrometer adjustable scope attempting to reach 600 yds . Long story short , because of the different mounting configurations of a micrometer scope mount there is no typical "moa" designation for the elevation turret graduations. The shooter is required to test and calculate poi shifts for each turret graduation. I knew my bullet weight , and i knew my velocity . The bullets are a custom casting so i also did not know BC. So after months of poi testing and gathering data i found that a BC of .270 and a moa scope graduation value of .4 gets me scoring at least the 8 ring from 200 yds out to 600. I spent a lot of time tweaking the BC to get my numbers in Stryloc to match my observed elevation poi shifts. My experience with Stryloc is in some situations the outputted numbers are just off sometimes by quite a bit. Wierd but it is what i observe.

 

[paul73]

well, scope is an arken epl4, and it is a solid performer, i kinda doubtful to susepect its clicks are way off from stated 0.1mrad...
dunno from what abgle to attack this.

the core issue now is the close 100 dope - as the diff between 1.6 and 1.8 at a 100 is quite substantial.
i can decide to 'trust' the strelok data, as 50yds zero is a ragged hole anyway, and simply unbolt and rotate turret from 1.6 it shows now into 1.8.
that would move 13 into 13.2. and move BC to 0.149, which also 'can' be true. or not.

sounds like a total bs now, dunno. but i will try to do it, as i want to use strelok table. will get to 50 with this setup to see what it will do to 50 zero and how far off it will be, if it will be.
it is damn difficult to judge anything there at the 50, as those adjustments are not too visible there.

 

[paul73]

went to re-check it this morning, and, after moving turret 2 clicks into 1.8mrad - it seems to be at perfect 0 for 25/50, so, go figure what went wrong there initially. heck with it. odd.
i zeroed it during winter, may be it was temperature related somehow.

 

[SJan]

went to re-check it this morning, and, after moving turret 2 clicks into 1.8mrad - it seems to be at perfect 0 for 25/50, so, go figure what went wrong there initially. heck with it. odd.
i zeroed it during winter, may be it was temperature related somehow.

Its no secret that temperature affects velocity
My personal recorded chronograph sessions with SK LRM show 26 more FPS at 85 degrees than at 50 degrees. Strelok shows that being a .7 MIL difference at 300y.
I have not checked at a lower temperature because I'm not shooting a match if its cold weather conditions. What were the conditions during your winter zero? vs your recent testing?

 

[paul73]

Its no secret that temperature affects velocity
My personal recorded chronograph sessions with SK LRM show 26 more FPS at 85 degrees than at 50 degrees. Strelok shows that being a .7 MIL difference at 300y.
I have not checked at a lower temperature because I'm not shooting a match if its cold weather conditions. What were the conditions during your winter zero? vs your recent testing?

I wish I could remember. It was January, I recall to set it quickly at 50, moved to 100 and it was set to 1.6mrad, and I did not have chrono with me.
I think, having this table now confirmed at 25/50, 100 and 300 should be adequate for any distance. Just need to show up at any event, finally, with it.

It was still shooting into almost same hole at a 100, but, a 300 spread was rather large, 3-4” both ways. Interesting stuff, I never shot 22lr that far, it was surprising.