establishing a new turret "0", for a new cartridge

[.308winguy]

I'm relatively new to long-range shooting. I have what is probably a basic question:

So, I have my dope for a particular round and have adjusted my turret to zero at 100 yds.

If I want to chrono, zero etc. a new round (different weight, powder load) do I include on my dope card (for my first round) include how many mils up from the bottom of the reticle be included as the starting point? I've never seen this addressed. In other words, how to you get back to the turret zero for previous outings? I hope this makes sense.
Thanks in advance!

 

[Glassaholic]

When you say "have adjusted my turret to zero at 100y" do you mean that you sighted the scope in with a particular cartridge for 100 yards so that the center of the crosshair point of aim (POA) is aligned with your point of impact (POI)?

Let's say the cartridge you zero'd is a 6.5 Creedmoor with a Barnes 127 solid, but now you bought a bunch of Hornady Match 147 ELD-M rounds and using your same zero you notice that the POI of the Hornady 147 is 0.2 mils low at 100 yards. Well, you can either re-zero your scope (can be a pain on some models) or you can adjust your solution by 0.2 mils regardless of distance. I keep track of these differences on all my load development (LD) sheets so I can adjust accordingly depending on which cartridge I'm shooting with.

Not sure if I understood your question correctly but hopefully this helps.

 

[.308winguy]

When you say "have adjusted my turret to zero at 100y" do you mean that you sighted the scope in with a particular cartridge for 100 yards so that the center of the crosshair point of aim (POA) is aligned with your point of impact (POI)?

Let's say the cartridge you zero'd is a 6.5 Creedmoor with a Barnes 127 solid, but now you bought a bunch of Hornady Match 147 ELD-M rounds and using your same zero you notice that the POI of the Hornady 147 is 0.2 mils low at 100 yards. Well, you can either re-zero your scope (can be a pain on some models) or you can adjust your solution by 0.2 mils regardless of distance. I keep track of these differences on all my load development (LD) sheets so I can adjust accordingly depending on which cartridge I'm shooting with.

Not sure if I understood your question correctly but hopefully this helps.

Thanks for your answer. To try to refocus my question a bit. I recently shot 1000 yds. (.308 / 175) my elevation was 14x mils. I can easily dial it back down to my 100 yd zero, which is only good for that load. I reload, and am trying to come up with a way to keep track of various loads, and where a 100 yd zero should be on the turret for each one. It seems that dialing to the bottom and counting back up, would be to get back to a zero for each different load. Again, maybe I'm not being clear, or I'm overthinking this...

 

[Glassaholic]

Thanks for your answer. To try to refocus my question a bit. I recently shot 1000 yds. (.308 / 175) my elevation was 14x mils. I can easily dial it back down to my 100 yd zero, which is only good for that load. I reload, and am trying to come up with a way to keep track of various loads, and where a 100 yd zero should be on the turret for each one. It seems that dialing to the bottom and counting back up, would be to get back to a zero for each different load. Again, maybe I'm not being clear, or I'm overthinking this...

Okay, so let's say you've zero'd your scope for the 308/175 right, so at 100 yards those bullets smack dead center of the target and your scope elevation and wind turrets are at zero. Now you decide to load some 155's and you change nothing about your scope, you leave it at the zero for 175's and you shoot a target at 100 yards and you notice that your tiny little group is sitting 0.2 mils above your POA (with no shift left or right). So now you know, that when you shoot the 308/155 load, you need to compensate 0.2 mils down regardless of distance, which means, let's say you take that 155 out to 1000 yards and your solution (ballistic engine) says dial 13.4 mils but that is assuming your "zero" is at 100 yards, but you know you are .2 mils high so instead of dialing 13.4 mils now you are only dialing 13.2 to compensate. Some ballistic engines will also allow you to compensate for different zeros (zero offset) between loads so you don't have to do the math yourself every time.

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Correcting zero for different loads out of the same rifle

This may be a foolish question, but in my twisted mind it makes sense. With ammo shortages and the like, I have a variety of 308 rounds that I would like to be able to use with my RPR without having to re-zero every time I change. The rifle is currently zeroed at 100 yds with 175 grain Federal...

www.snipershide.com

 

[.308winguy]

followup: I get changing the elevation / windage for the "next" round being zeroed, but it seems like you are building a "house of cards", constantly adding / subtracting from the original round 100yd zero. Seems like it would be easy to get "lost"... esp. with multiple rounds.

Thanks for your answer. To try to refocus my question a bit. I recently shot 1000 yds. (.308 / 175) my elevation was 14x mils. I can easily dial it back down to my 100 yd zero, which is only good for that load. I reload, and am trying to come up with a way to keep track of various loads, and where a 100 yd zero should be on the turret for each one. It seems that dialing to the bottom and counting back up, would be to get back to a zero for each different load. Again, maybe I'm not being clear, or I'm overthinking this...

 

[Glassaholic]

followup: I get changing the elevation / windage for the "next" round being zeroed, but it seems like you are building a "house of cards", constantly adding / subtracting from the original round 100yd zero. Seems like it would be easy to get "lost"... esp. with multiple rounds.

Yes it would which is why you would adjust zero offset in ballistic engine.

 

[Steel+Killer]

If I have a rifle that I know I am going to shoot different bullet weights / speeds I make the one that would shoot the "highest" at my 100yd zero (which is probably going to be the lightest / fastest bullet) the "0" zero on the turret so any other round/load I shoot from there will be a slightly "higher" zero offset from my "0".

Then on my ballistic app I create a new profile for each "load/round" and input the "zero offset" it's not that hard or really that much to keep up with you just have to remember to use the correct profile for the round you are shooting.

IMO it beats physically resetting the turret back to "0" for each different load/round.

I basically told you the same thing @Glassaholic did in a different way.....

 

[Steel+Killer]

Wanted to add that if you move scopes around to different rifles and use a really good mount that has good / repeatable "return to zero" you can pretty much use the same technique, figure out which rifle requires the elevation turrets to be turned down the lowest for zero make that rifle the "master" rifle where "0" is actually "0" and then figure out the zero offsets for each other additional rifle from there. Works great especially with switch barrel rifles like AIs.

 

[FredHammer]

This approach just invites Murphy to fuck up your program.

 

[.308winguy]

This approach just invites Murphy to fuck up your program.

just for s&gs, I asked AI:
Establishing your turret zero for a specific round involves setting your turret so that it aligns with the zero distance for that particular round. If you're resetting your turret to a previous zero, bottoming it out and counting mils back up is one method you can use. Here's a step-by-step guide:

1. Record Current Turret Settings: Before you adjust your turret, it's important to note down its current settings. This ensures you can return to your previous zero if needed.
2. Bottom Out the Turret: Rotate the turret in the direction that lowers the elevation until it stops. This is typically clockwise, but it depends on your scope.
3. Count Mils Back Up: Each click on your turret represents a specific angular measurement, usually measured in mils (milliradians) or MOA (minutes of angle). Refer to your scope's manual to determine the value of each click. Count back up from the bottomed-out position to the desired zero for the specific round you're using. For example, if your zero is 4 mils up from the bottomed-out position, you would click the turret 4 mils up.
4. Confirm Zero: Once you've counted back up to your desired zero, confirm it by firing at a target and making any necessary adjustments based on the shot placement.
5. Record New Turret Settings: After confirming your zero, record the new turret settings for future reference.
6. Repeat for Different Rounds: If you have multiple rounds with different zeros, you can repeat this process for each round, always ensuring you record and confirm each zero accurately.

Remember to always verify your zero by shooting at targets at the intended distances after making adjustments. Additionally, it's a good practice to periodically check and confirm your zero to ensure consistency and accuracy.

 

[Steel+Killer]

This approach just invites Murphy to fuck up your program.

While I agree I probably wouldn't make a "secondary" rifle a rifle I would take on a lifetime out of town hunt, take it to the battlefield, or competition, but if done correctly for banging steel it will and does save time and ammo not rezeroing every load/barrel, but I do get the apprehension.