I have a strange sighting situation maybe you fellows can help with.

It is a .375 Ruger Alaskan.

Now everything is working perfectly although the sighting in has thrown me for a loop.

The scope is a Nikon 2x8-32 Monarch 3 with a BDC recital.

A wonderful strong clear scope.

The load is a 300 grain Sierra spitzer boat tail
2554 FPS average for 10 shots with ES-15 and SD-7.

It will place 5 shots at 100 yards into 3/4 in. Consistently.

I used the Nikon app for this scope and load to sight it in for the corresponding BDC sight points at 8x.
This showed a 150 yard zero with the 1st lower BDC circle at 219 yards and the third at 296 yards.
The trajectory program I used for this bullet with its ballistic coefficient sighted at a 150 yard zero showed a +1 in. at 100 yards and a -2.7 in. at 200 yards.
The rifle is sighted in at +1 in. at 100 yards. Groups perfectly.
At 200 yards using the lower BDC circle which should show a drop at -2.7 in. Is grouping 3 shots at 1 1/2 in. BUT, at + 2 in. above the target.
Am I doing something wrong here???

Have you checked your actual velocity with a chronometer?

Yes.
10 shot average with ES & SD.

What is the height of the scope reticle compared to the bore?

Does the ballistics program account for altitude, temperature, barometric pressure?

George

Hieght is medium, 1.5".

No, I did not take into consideration pressure, etc.

I did not apply it not thinking it would cause such a discrepancy.
It's seems I may have been wrong.

Although, a 4 1/2 in. discrepancy seems a bit extreme.

I think what I will do tomorrow is using the first BDC circle I will lower the group to sight that at 200 yards.
I will then check where the 100 yard is grouping then test the second BDC circle to see where it is placing at 300 yards.
I'm getting the feeling at 100 yards it may be dead on or a little high.
Considering I know the velocity as a fact and the altitude here in PA where I'm located is about 500 feet above sea level and the average temp. Is 70-75 deg. The only thing I can think of is I am not properly inputing information or the ballistic coefficient is superior than indicated.

so, simple rule --
aim at hair, not at air

and 2" at 200 doesn't mean a THING ... i can't shoot 2" off hand at 200 with a .1" gun...

2" at your scope likely means you aren't holding the zero nikon expects you to

Agree with jeffeosso, that is fly poop specks in the black pepper with a .375 Ruger at that range. Excellent shooting.

Riflecrank Internationale Permanente
NRA Life Benefactor and Beneficiary
https://home.nra.org/

In looking at the Nikon app, your zero should have been right on at 100. Also, as I understand the app, the magnification setting of the scope also makes a difference.

quote:

Originally posted by PRW:
In looking at the Nikon app, your zero should have been right on at 100. Also, as I understand the app, the magnification setting of the scope also makes a difference.

Yep, it does -- i have the close to same scope and same app --

the IT REALLY MATTERS part is that the app assumes you are shooting at whatever mag setting the app predicts for your selection -

I think your over thinking the issue..I sight all my guns in at 3"s high at 100, most then are 4 inches high at 200 and on a around 250 to 300 yards depending on caliber..A big bore is normally 3 high at a 100, and on at 200. about 6 inch drop at 300 depending on the caliber.

I hold on hair center body to 200 and top of back passed that, seems to work every time.I don't shoot passed 300 with a big bore.

This is a generalization, I would never leave the house without testing each gun at 100,200 and 300 yards as there is a variation between guns to one degree or another and sometimes its just enough to cause problems, so test them before you go on an expensive hunt, toss the charts.

KISS principle is best for the hunter.

Now I know this is no more than technicalities.
And I am doing this for the fact that I purchased a scope with a BDC reticle so that I could take advantage of the settings.
I went out to retest today.
Using the Nikon app with all the proper settings for this round and bullet at the tested velocity.
According to the app.
The cross hairs show an impact at "0" at 100 yards. The first lower circle shows 184 yards.
The second circle shows 266 yards.
This is at 8x.
The test showed the crosshairs at 100 yards "0".
The first circle at 200 yards showed "0" dead on. The second circle at 300 yards showed a 3 inch 3 shot group + 2 inches high perfectly centered.
All inputs were correct.
Although for hunting purposes this is meaningless because out to 300 yards this rifle ammo combination is capable of performing its job.
All I am implying is that either the app is grossly inaccurate or the BDC recticles capabilities are over exaggerated.

I had a Leupold VX3 2.5-8x36mm Boone & Crockett reticle on my 375 Ruger Guide Gun. I thought this reticle was too busy on this caliber of rifle. I switched to a standard duplex reticle in the same scope. I sight dead on at 200yds with my 300gr. Nosler Accubond load traveling at 2590fps. Average 1/2" 3-shot group at 100yds. My elk hunting load. I have scope mounted with Alaskan Arms quick detach low rings. Thinking about getting a Leupold VX3i 1.5-5x20mm heavy duplex with same quick detach rings or peep sight for my Woodleigh 350gr. PP hand load traveling at 2391fps. with just under 1" group and sight dead on at 100yds, for thick skinned game.

Like Ray, I try to keep it simple. 3" high at 100 on all my hunting rifles. Started doing this back in the mid 80's after reading one of Bob Hagel's books. Always worked great for me. Keeps me in the vitals out to 300.