2600+ FPS, 123 gr. bullet, 20" barrel... Problem?

[McFireFighter]

If you have the room to shoot out to 300-500 yards. If you are zero'd at 100 yards. Record the drop at 300 yards or whatever yardage you use. Use a ballistic program with the data for the bullet you are shooting and manipulate the velocity in the app until it reflects the drop in inches at the yardage you shot. It's not going to be an exact science but should be close. I tested it on my ballistic app and it seemed to work.

[Vasux86]

If you have the room to shoot out to 300-500 yards. If you are zero'd at 100 yards. Record the drop at 300 yards or whatever yardage you use. Use a ballistic program with the data for the bullet you are shooting and manipulate the velocity in the app until it reflects the drop in inches at the yardage you shot. It's not going to be an exact science but should be close. I tested it on my ballistic app and it seemed to work.

This is the process I used (at different distances) and it worked fine. There are probably easier ways to do it, but this was the only way I knew.

[McFireFighter]

Awesome.

[LRRPF52]

You will get more resolution at 600yds or farther if you can. I use calipers to measure my optic height above bore, so there is no room for optic height to throw another variable into the mix.

[McFireFighter]

You will get more resolution at 600yds or farther if you can. I use calipers to measure my optic height above bore, so there is no room for optic height to throw another variable into the mix.

I do the same in all of my ballistic apps. Amazing what a difference it makes.

[JASmith]

If you have the room to shoot out to 300-500 yards. If you are zero'd at 100 yards. Record the drop at 300 yards or whatever yardage you use. Use a ballistic program with the data for the bullet you are shooting and manipulate the velocity in the app until it reflects the drop in inches at the yardage you shot. It's not going to be an exact science but should be close. I tested it on my ballistic app and it seemed to work.

If you have room to shoot put to 300-500 yards, zero at 200 yards observe what you get at 100, 250, 300, 350, 450 & 500 yards.

First, your drop tables are well established in grund truth for the temperature you shot at.

Second, you may find that holdng one's shots to an intermediate range is well advised for ethical hits in the vital zone.

[FW Conch]

^ This works for me :-) ^

[Vasux86]

You will get more resolution at 600yds or farther if you can. I use calipers to measure my optic height above bore, so there is no room for optic height to throw another variable into the mix.

I did this as well. Although most apps or programs I looked at default to 1.50", the center of my scope was actually 1.59" above the center of the bore. I'm curious to know how much difference that makes when you get past 500 yards.

If you have room to shoot put to 300-500 yards, zero at 200 yards observe what you get at 100, 250, 300, 350, 450 & 500 yards.

First, your drop tables are well established in grund truth for the temperature you shot at.

Second, you may find that holdng one's shots to an intermediate range is well advised for ethical hits in the vital zone.

I like this. I'm always a fan of results over predictions/theory, especially when you need to make a decision about whether or not to take an ethical shot.

[McFireFighter]

Agreed. And thanks for elaborating on my theory. Made sense to me but sometimes difficult to put in words.

[LRRPF52]

I'm not seeing how it is physically possible to have a scope center 1.59" from an AR15 bore. 2" would be extremely low. 1.59" would have to be some tiny tube with Weaver rings clamping it to the upper.

[McFireFighter]

I think mine is 2.25" with aero precision mount. Don't quote me on that.

Ballistics had my updated height adjustment. It is 2.25, not 2.2". Still updating my records since the phone reset.

[Vasux86]

I'm not seeing how it is physically possible to have a scope center 1.59" from an AR15 bore. 2" would be extremely low. 1.59" would have to be some tiny tube with Weaver rings clamping it to the upper.

I'll double check tonight and see if it's still 1.59"

[Vasux86]

I'm not seeing how it is physically possible to have a scope center 1.59" from an AR15 bore. 2" would be extremely low. 1.59" would have to be some tiny tube with Weaver rings clamping it to the upper.

Here's the method I used a few months ago. Tell me if you would recommend using a different method.

I removed the handguard and measured from the bottom of the barrel to the top of the scope with a caliper. I then measured the OD of the barrel and the OD of the scope. I subtracted 1/2 OD of each from the total measurement from the bottom of the barrel to the top of the scope.

[McFireFighter]

I measure middle of bolt to middle of windage cap.

[Vasux86]

I'm not seeing how it is physically possible to have a scope center 1.59" from an AR15 bore. 2" would be extremely low. 1.59" would have to be some tiny tube with Weaver rings clamping it to the upper.

Good call on this. I don't know what went wrong last time, but I redid my measurements and my scope height is actually 2.79"