Ballistic App

[johnnyk]

Currently running Strelok Pro. I ran the free app for a couple of years with no problems until I added a .308Win. I'm pretty sure I added all the necessary data right but out to 1k and beyond my bullet was hitting the dirt. The calculation was calling for 32.37 MOA @ 1k. Now my shooting buddy shoots pretty much nothing but .308's (he's got 4 I think) and he knows this cartridge takes at least 40 MOA to hit at 1K.
I don't understand why the app is coming up short. I have lowered the velocity but I'm not satisfied with that. I'm pretty sure the speed is right and I'm doing good up till 1k.
I bought the Pro version thinking that would help and maybe I could get that .308 printing like it should.
Used Strelok Pro this weekend with my 6.5-284Norma, 147gn ELD-M @ 3045fps and it's going the same route. For instance, at 1300yds app called for 31.1 MOA but I actually had to dial 37MOA to be dead on. I printed a 3" group at this range (with a witness - which is my best, and most luckiest group ever) but what the heck is going on?
Do you think it could be that a BC correction is required? I know Sierra list decreasing BC's for their SMK's as velocity drops but how the heck do I figure those out? Hornady doesn't list this info, do they? I thought with their new ELD bullets that the Doplar Radar had "averaged" out the BC.
Anybody got an idea what it could be? JohnnyK

 

[Bbear]

I have Strelok Pro as well. I'm also seeing problems with the 308. Now, mine is strictly for hunting and smacking (or trying to smack) steel out to 600 or 700 yards. Three weeks ago I dialed what Strelok said on my scope and hit about 10' short of the target at 350. A friend ran it on something else and we came up with 1.2 MOA more than what Strelok said.
Playing with the BC to get Strelok to match, I came up w/ a BC for the Sierra 165 GK at .575.

I'd be interested to hear anyone else's comments.

 

[Bullet bumper]

There is no single BC that can predict a whole trajectory out to long range.
When you model a bullet you get a whole list of BC's at different velocities .
Some place in that long list at one single velocity step is the biggest BC number .
Which one do you think the bullet maker will quote ?
Off course the largest number to sell bullets . Actually what Sierra does is far more honest and it sometimes quotes 3 BC's at 3 velocity boundaries which helps to predict a more accurate trajectory over a wider spread of velocities from say short range to further down range .
Now if you are punching in that one BC number it will be more correct at some point in the trajectory and less correct the further the bullet flies past that velocity point and looses more velocity down range .
Make sure you have the actual muzzle velocity corrected for chrony distance and all the correct atmospheric , altitude and line of sight angle inputs right .
Then play with the BC number lowering it until the predicted drop gets you onto the target . Then when you get the bullets on the target finer adjustments can be made . That BC is now closer to what it actually is at that longer range and lower velocity under those conditions . Once you find the more realistic BC for 1000 you can change conditions in the program as required and it should stay fairly accurate around 1000 . Make sure you are entering the correct Drag Function for the BC quoted as the big numbers are usually G1 and the more sleek boat tail bullets with smaller numbers usually G7 .

 

[Kmccord]

I have heard, for 600+ yards, it is better to use the G7 BC, not sure if this is true.

 

[toddc]

I use Strelok Pro extensively and it matches any other app pretty closely. Are you sure you arent using a G1 in the G7 or CMD profile? I plugged in a 308 with 175 and got 41 moa. Also PRO allows multi BC. I would guess its operator error, ballistic apps are pretty straightforward math, no weird algorithms or such. I would get a factory load from the library and see how it differs from your inputs.

 

[ShtrRdy]

Did you ever do a tall target test to get a measurement on your scopes adjustment scaling?
https://www.youtube.com/watch?v=12Wf0Cuwwi8