I have a 300 yard lane at my gun club. This is the longest lane we have. With my .308 and my 6.5 Grendel, I attempt to group shots inside of a 3 inch circle. If I do my part, I can often achieve sub-moa results. This more so with the bolt-action .308 Savage Model 10.
I have zeroed the rifles with my favorite hunting rounds. I have tried to strike a good balance between terminal effects and high ballistic coefficient rounds. The results are usually predictable and consistent.
The problem came when I would switch to other rounds. I use the Hornady 4 DOF ballistic program. I used to think that if I gave it good data I would be able to hit the circle by dialing the correction into my scope. Very often, it did not work out that way. I might get close, but not what I expected.
It occurred to me that my rifles were zeroed to those specific hunting rounds. The ballistic solver assumes zero as it’s starting point I suppose. It builds an error into the numbers from the start.
My question for the group: Is there a workaround or shortcut to get around this issue? Or would I need to re-zero the scope for the new round I want to use? This is not the end of the world of course, but if there is a way to avoid re-zeroing for each round change, I would like to learn how.
It is the round that makes the shot or not. You ever heard of the definition of insanity? Doing the same thing over and over again expecting a different outcome.
Ballistics are just like that, if you use the same round and expect it to do something else you will be disappointed by the results. Changing the round changes everything. I reload my rounds for precision shooting. The brass weighs the same with the same length, same grain of bullet, (I check that) same grain of powder. If I change the bullet manufacturer I would have to go through and check the measurements and its weight because each and every adjustment means it adjusts the ballistics. Accuracy come by consistency of each round being identical.
So simply said yes, new ammo check and adjust your zero.
Every round will perform differently, unless loaded to be the exact same every round. If you change brand, or any part of the round, your impacts using the same calculations will be changed. If you are shooting for precision, you’ll have to re-zero every time you change anything.
I am probably not explaining this real well. I will preface this by letting you know that I am not handloading yet. Back to the subject.
As an example, my zero round is a 150 grain Hornaday SST. Everything is great with the numbers my ballistic calculator gives me, not counting a bit of adjustments for real velocity versus actual velocity.
When I get a new round, I will plug the performance numbers into the ballistic solver. One of them is a 168 grain SST. The solver gives me an elevation correction. I plug that into the scope and shoot. Simply put, the results were somewhat close, but not as good as expected.
I was initially puzzled as to why. Then it occurred to me that the rifle was zeroed for the 150 grain SST. Of couse the ballistic solver would assume the gun was zeroed for the 168 grain. Then the errors made sense.
My question involved any shortcuts one could use to avoid re-zeroing the rifle for the new round. I could not think of anyway to avoid re-zeroing but thought I would ask you guys. That’s it. I probably did a poor job with my description of the issue.
It makes me wonder about a sniper, as an example. If they are laying in their hide and wished, for some reason, to select a different round to shoot, would they be able to do that? Would they have the same problem or do they just dope it with firing data?
For my purposes, I now know that if I wish to change rounds, I need to re-zero. I figured as much, but wanted to ask.
You can use your 150 gr zero and the app. You’ll have to add the extra step of making the corrections to your desired outcome from the info the app gives you, then record that data and apply it to future shots. Basically you make a dope book off what the app gives you plus your corrections.
I set the zero on both at 300 yards but if you look at the both of them the arch is10 inches high on 150 and 6 niches on the 168 grain, So, the difference is four inches. if the difference is four inches then if you adjusted from that info, it would be the difference.
So, I have to ask if the difference that your calculator gives is anywhere close to that?