Going into match blind

[NJRaised]

Between work and family life I have not had a chance to confirm data prior to a match this weekend. Need a hand.

Shooting a 223 rem, 1/7 bartlein, 2805fps, 75eldm, height over bore 2.2”.

I’m zeroed well at 100 yds.

I’m running data in my kestrel , and between G1 or G7, I’m getting almost a half mil difference in holds.

What do you guys recommend?

Luckily it’s only a 600yard match.

 

[OREGUN]

Can you shoot at a distant target (400 to 600) during zero? Ask the MD if there’s something you can shoot around 600. Shoot at a spot on the berm if he doesn’t want you shooting his targets.

if yes, put your g7 bc from the box, your chrono speed, and all other relevant data in the kestrel. Shoot the farthest target you can shoot, adjust speed in kestrel until dope matches and call it good. Don’t worry about bc, your ranges are too short for it to matter.

if no, do same and make needed adjustments after hitting/missing your first target/first stage worth of targets. Get a squad mate to try to give you as accurate a call as possible, after the stage, on how high or low you were so your adjustment in the kestrel can be as good as possible.

 

[6.5SH]

FWIW the AB library likely has a mistaken G7 value for the 75 ELD-M, they show 0.238, it is higher than Hornady lists here:

Ballistic Coefficient - Hornady Manufacturing, Inc

A-Tip®, ELD® Match, and ELD-X® Ballistic Coefficient Values Hornady originally published “800 yard”* average Ballistic Coefficient (BC) values for ELD-X and ELD Match bullets. This was done to provide the most usable BC from a trajectory prediction st...

www.hornady.com

If you check the various PDM's it is also higher than anyone tested at.

That all being said, I get a 0.1 mil difference at 600 yards even using the inflated G7. Double check your inputs, there is something else likely amiss.

 

[kthomas]

I would use AB's CDM (custom drag model) if you have that available to use.

I've shoot a couple of matches ballistically "blind", where I haven't had a chance to prove out dope to distance. But I've always had reliable results using AB's CDMs, at least with Berger projectiles.

 

[Ghost29]

Use Gravity Ballistics, it’s easy! You get real data for your rifle.

1) Print Gravity Ballistics sheet
2) Shoot and record
3) true muzzle velocity in Kestrel

 

[OREGUN]

Use Gravity Ballistics, it’s easy! You get real data for your rifle.

1) Print Gravity Ballistics sheet
2) Shoot and record
3) true muzzle velocity in Kestrel

Pretty sure he’s saying he doesn’t have time to do that.

 

[Ghost29]

If he can shoot to 200 during zero, he would have the time.

 

[DocUSMCRetired]

Between work and family life I have not had a chance to confirm data prior to a match this weekend. Need a hand.

Shooting a 223 rem, 1/7 bartlein, 2805fps, 75eldm, height over bore 2.2”.

I’m zeroed well at 100 yds.

I’m running data in my kestrel , and between G1 or G7, I’m getting almost a half mil difference in holds.

What do you guys recommend?

Luckily it’s only a 600yard match.

If it is a flat based bullet use the G1, if it is a boat tail use the G7. If you have the option, run a CDM for the best accuracy. The closer you can get to 600 yards on sight in the more confidence you will have when you confirm the predictions.

 

[OREGUN]

If it is a flat based bullet use the G1, if it is a boat tail use the G7. If you have the option, run a CDM for the best accuracy. The closer you can get to 600 yards on sight in the more confidence you will have when you confirm the predictions.

75 ELDM is definitely a boatail.

 

[Changed]

Don't forget to enter your actual bullet length in the kestrel.

 

[OREGUN]

Between work and family life I have not had a chance to confirm data prior to a match this weekend. Need a hand.

Shooting a 223 rem, 1/7 bartlein, 2805fps, 75eldm, height over bore 2.2”.

I’m zeroed well at 100 yds.

I’m running data in my kestrel , and between G1 or G7, I’m getting almost a half mil difference in holds.

What do you guys recommend?

Luckily it’s only a 600yard match.

So what did you end up doing and how did it work?

 

[NJRaised]

So what did you end up doing and how did it work?

I ran my chrono speed, g7 , and let it eat. Data from kestrel was dead nuts on and ended up taking 4th overall (tied for second on points, #4 based on time on prs barricade).

 

[OREGUN]

I ran my chrono speed, g7 , and let it eat. Data from kestrel was dead nuts on and ended up taking 4th overall (tied for second on points, #4 based on time on prs barricade).

Excellent. Well done.