Primary Arms ACSS scope and handloading

[BillJ]

when using strelok+ (i have it) how do you get an accurate number for the temperature sensitivity factor for your powders?

do you know of a published chart of that? is it something that's in quickload? or is it a guess type issue?

when using any kind of calculator, GIGO applies, so your numbers have to be as accurate as possible for an accurate data output.


if there's not a chart, is there a method for determining this value in the calculator? lets say shooting the same load in different temp conditions and doing some math on the FPS variance....

Temperature sensitivity of powders is rarefied air stuff. Leave that to the group shooting 1000 yard +. Age of powder and barrel/chamber temperature can also impact it. The only way I know of to test it is to burn powder in a controlled environment.
Its not a GIGO worry on something like that. Im sure someone someplace has the data, but Ive never sought it out.
Strelok pro and maybe the + has an option for truing your velocity. TLDR version of it is you zero at 100 yards saying that your velocity is X fps then you move to 200 yards and lets say it should be 10 clicks of elevation change, but in reality it took you 9 or 11. you punch that number in and it compensates to the real FPS number.

Stick with the basics of weight, velocity, ballistic coefficient, temperature, humidity, and barometric pressure and you will get repeatable results.

[plant.one]

i have a magnetospeed, so getting accurate FPS numbers is relatively simple.

however it does ask for a powder temp sensativigy factor, which is why i specifically asked about it. if in fact it is a truly unicorn figure, why do they ask for it?

i can appreciate that firearm/calibers would product a different number which is why i asked if there was a formula to calculate it. i guess for now i'll just leave the default value in and keep collecting different temp values as i shoot throughout the year.

[BillJ]

It's just the more information the better. Like madmax said Igor may be able to point you at something. If he has a setting for it, I'd wager he has some sort of information.

Is it going to produce a noticeable difference on someone shooting intermediate ranges? Nope. Is it going to effect the guy doing 1600 yard shots? Absolutely.

Just looked at the values built into the program on it. For the default with a 30 deg temperature swing its less than 50fps. So nothing I'm even going to pay attention to.

[SuedePflow]

Well, here it is with my Nosler 125gr load. I downloaded Strelok Pro last night but haven't had any time to play with it yet. This screenshot below is courtesy of Jeff at Primary Arms.

[r.tenorio671]

...FWIW, both of my PA 4-14x scopes had the ballistics charts in the manual that comes with the scope. It lists the bullet weights and FPS of each that the reticle is calibrated to. If you can match the FPS of the listed cartridges with your handloads or factory ammo, then the match up to the reticle hash marks will be greater. An accurate FPS reading of handloads/factory rounds thru YOUR barrel(s) is crtitcal, rarely does it match the number listed on factory cartidge boxes or handloading manuals.

... a ballistic app like Strelok+ can take your actual FPS readings and re-calculate the drops for that cartridge in YOUR barrel and display the graphics for the "calculated" drops. Again, one still needs to validate what it's displaying against known distance zeroing/shooting.

...I use Strelok+ for 3 different calibers, 3 different scopes, 2 different 300BLK barrels and multiple bullets/powders/primer/COAL for each. Using just my 5-10ft chrony readings, the calculated drops were better than 95% accurate at 100Y/M, at 300M, it was less but not significantly, the "truing" feature allowed the tweaking/correction needed.

[jwb47]

I have the primary arms 7.62x39 \ 300 blackout optic on an ak and it has bullet weight and velocity listed for the ak and 300 blackout . Im pretty happy with it . I done this at 300 yds with an ak and the cheapest 7.62 ammo I could find firing off a cadwell field pod . it wont win camp perry but if I can plug a yote at 300 yds with an ak Im good to go.