Painless load development (mine)

[Carl Ross]

As a relative newbie to the long range game, is there a thread that focus on truing at long range? Im assuming the best method is putting paper out as far as possible and verifying your impact, but after that i get lost. Do you then fiddle with your BC until your dope chart matches the actual results? Something else? Don't want to hijack this thread so any links to relevant threads are welcome.

If I have a GOOD chrono (Garmin, Labradar, Magnetospeed, Ohler) I trust the velocity and true the BC. If you have to move a CDM more than a few percent, I'd double check the rest of your inputs, they're usually pretty good.

If I'm not using one of the chrono's listed above, I trust the BC and true the velocity.

 

[Alpha Echo]

Yeah, I have a Garmin, and this is exactly the point where I've gotten confused. I've heard both before - true the velocity vs true the bc. I could never understand truing the velocity when I have actual hard data from my rifle, whereas BCs are published and I've heard on more than one occasion inflated.

 

[Castle Rock]

Over hunting distances as long as you are truing it probably doesn’t matter, however the ballistic aps make it easier to use the velocity solution.
It’s also far more common to get accurate BCs now than in the past.

 

[Formidilosus]

Yeah, I have a Garmin, and this is exactly the point where I've gotten confused. I've heard both before - true the velocity vs true the bc. I could never understand truing the velocity when I have actual hard data from my rifle, whereas BCs are published and I've heard on more than one occasion inflated.

Legit BC’s are available for most bullets. The BC variation from rifle to rifle is small: 10-15 G1 points at most (I’ve never seen more than 10 that I can remember over Doppler). Look at what a different between .6 G1 and .590 G1 at 800 yards is with same MV.

The amount of people that have the skill and ability to see the difference in real BC between rifles at even 800 yards is laughably small, and anyone (including me) that has to ask or wonder are absolutely not them.

The biggest source of error with each shot is MV. That is why it is adjust first. And, when adjusting MV from the muzzle to the distance where trued, it will backwards line up all points and absorbe any error in zero offset, scope increment click value, etc- better than adjusting BC.

 

[Alpha Echo]

Thank you for the detailed explanation Form!

 

[Chet707]

Follow up post after truing at 550.

Ended up with a trued velocity of 2850 with 77 tmk and 24 gr varget. Shooting over a buddies garmin had a discrepancy of 90 fps slower than my trued velocity. I kept my own velocity and just went 3 for 3 at 871 and 525. Good enough for me!

 

[NoDakhunter]

Legit BC’s are available for most bullets. The BC variation from rifle to rifle is small: 10-15 G1 points at most (I’ve never seen more than 10 that I can remember over Doppler). Look at what a different between .6 G1 and .590 G1 at 800 yards is with same MV.

The amount of people that have the skill and ability to see the difference in real BC between rifles at even 800 yards is laughably small, and anyone (including me) that has to ask or wonder are absolutely not them.

The biggest source of error with each shot is MV. That is why it is adjust first. And, when adjusting MV from the muzzle to the distance where trued, it will backwards line up all points and absorbe any error in zero offset, scope increment click value, etc- better than adjusting BC.

I trued my 22cm with 75 eldms out to 655yds a few weeks ago using my revics . Hornady lists a G7 of .235 and mine trued at .196. I have a known MV with 30ish shots down the garmin and have an accurate scope height measurement. Thoughts?

 

[Formidilosus]

I trued my 22cm with 75 eldms out to 655yds a few weeks ago using my revics . Hornady lists a G7 of .235 and mine trued at .196. I have a known MV with 30ish shots down the garmin and have an accurate scope height measurement. Thoughts?

Yes. Something is off. Zero is slightly off, crosswind or up/down drafts, etc.

 

[NoDakhunter]

Zero was checked at 100 yards in same session with 10 shot group. Shooting in flat ground. Reading on multiple things here I’m also puzzled. Had a ~6 mph wind coming from 5 o’clock. Will recheck next week.

 

[Castle Rock]

Check the simple things first, how good is the rangefinder, is it set to yards or metres