I just shot my new/used 416 Rigby for the first time, with a newly mounted my scope,and was suprised at how the point of impact changed between 25 and 100 yards. At 24 yards the first shot was 6" left and 6" low. 24 clicks up and to the right only brought it over an inch and up an inch. Many clicks and rounds later I was on the money at 25 yards.

I then shot at 100 yards. It was 7" high. With my 30-06, 25 yards and 100 yards are usually close the same POI.

I did not shoot it again at 25 yards.

So, is this normal? What happens if your sighted in at 100 yards and then need to shoot a dangerous animal head on at 12-25 yards? Seems I'm missing something.

I used the "Remington shoot" program. They didn't have 416 rigby but they did have the 416 remington. Sighted zero @ 25 yards you would be 2.02" high at 100 yards. Download the free program yourself and see.

Remington free shhot program

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At 24 yards the first shot was 6" left and 6" low. 24 clicks up and to the right only brought it over an inch and up an inch. Many clicks and rounds later I was on the money at 25 yards.I then shot at 100 yards. It was 7" high.

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I had the same thing happen once. It was my scope that was broken.

Scott,

That sounds very odd for that gun. I would guess it may be the scope or the Warnes Rings.

Do you have access to another scope to confirm this? What loads did you try? What kind of groups did you get at 100 yards?

Tim

First thing people need to realize is you can't sight you gun in at 25 yards. Like you said it takes a lot of adjustment to see the bullet impact change. Now look at it like this. You are 1 inch off at 25 yards you have to move the adjustment 4 times the amount you would at 100 yards. But the impact is in small increments and hardly noticed. Now look at 100 yards and be off 1 inch and it only takes 4 clicks if your scope is in 1/4 inch increments to move that inch which would of been 16 clicks at 25 yards. What I have found best and I do shoot a lot is I get my gun on paper at 25 yards, I use my bore sight first then shoot. I then move my target to 100 yards and do my sight in. If I shoot 1 inch high at 100 yards and then move back to 25 yards the impact at 25 yards is the same as my 100 yard sight it. But it will not work the other way. I hope this made scene. Just remember 25 yards is just to get you on paper. This works with al calibers bot just the 416.

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Originally posted by SBT:
I just shot my new/used 416 Rigby for the first time, with a newly mounted my scope,and was suprised at how the point of impact changed between 25 and 100 yards. At 24 yards the first shot was 6" left and 6" low. 24 clicks up and to the right only brought it over an inch and up an inch. Many clicks and rounds later I was on the money at 25 yards.

I then shot at 100 yards. It was 7" high. With my 30-06, 25 yards and 100 yards are usually close the same POI.

I did not shoot it again at 25 yards.

So, is this normal? What happens if your sighted in at 100 yards and then need to shoot a dangerous animal head on at 12-25 yards? Seems I'm missing something.

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Remember, you will need four times as much adjustment to move your POI at 25yds. as opposed to 100yds. That's normal; what's not normal is for your POI to be 7" high at 100yds. with a 25yd. zero (Assuming standard .416 Rigby loadings).

First, check to see that your scope is not torqued in the rings. Also, make sure it is not slipping under recoil.

Second, shoot your gun without changing magnification, if it's a variable.

Third, switch scopes to one that you KNOW is good.

George

Tim,
I know it is not the rifle, it is great. My groups were within 1 1/2" at 100 and single hole at 25. I also knowthe rifle shoots better than I do. I think it must be with the scope.

George,
How do I determine if the scope is tourqed? I rechecked all the screws, all were tight and the scope did not appear to have moved. Yes, I did change magnifications from 1.5 at 25 yards to 5 at 100 yards. The scope is a Leupold 1.5-5x20 standard duplex. I traded for the scope but it appears as new. I do not have another scope to try and at $100 plus for a box of shells, this could get expensive. Any quick ways to tell if the scope is good?

Fit the scope on another rifle that is cheaper to shoot and check it there.

If you hit 6" left and 6" low at 25 yards the scope should be moved about 96 clicks right and up about 80 clicks.

If all is good this should get you about centered left/right and about 1" low at 25 yards.

From here you shoot at 100 yards and adjust 1/4" per click at that time. Small errors at 25 yards are magnified X4 at 100 yards and it's easy to screw up.

If this is about what you did, you're about right and the scope is probably ok.

Redhawk,
as I understand (or don't) 25 yards is the "magic" number if you scope (LOS) is 1.5" above the barrel...

the guestimate is that the bullet will be angled (a bullet only"falls") up slightly and crosses LOS at some 2 points....

at 1.5 above the bore, the GENERAL rule is that it will cross about 25 yards and then about 100 yards... as sight in as actually determine where in the bullets path it will cross the line of sight... and so hits where you are aiming.

that the rifle is sighted in means you KNOW where it will hit at that convergence.

after all, LOS is a line, and a bullet travels in an arc. that arc is angled UPWARDS (under usual circumstance)

this is why velocity consistency is so important, that the arc stays the same shot to shot.


that the arc crossing the line can be from 23 to 27 is not THAT important.

and yes, i've been surprised at how off a 25 yard gun is at 100!!


So, if a gun is drilling one hole at 25, in the bull, it should be close to that at 100... close, not on....

the rise of that arc (from muzzle to sight in point) is 1/2 the critial information for determing max point blank range, btw.

jeffe

The most serious problem with sighting in at 25 yards is not that the adjustments must be magnified, but rather that there is not necessarily a unique mathematical condition for the proper adjustment.

Think about it: nearly every load in the world will cross the line of sight at roughly 25 yards. If you are near that point all ballistic solutions (trajectories) for that load will move through that point or very near to it. You will probably have at least ten times the scatter in your aim than is found in the sight adjustment necessary to make you correct at 100 yards. I know because I have done this. You can be nearly dead on at 25 yards and be 8 inches high at 100 yards, if you are close to that magic crossover point.

Get on the paper and then shoot at 100 yards at a large sighting grid.

Another tid bit I learned: forward mounted scopes do not necessarily adjust like normally mounted scopes. I found that any adjustment at 100 yards was twice the expected amount at 200 yards (ie, 4 times the normal amount).

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Originally posted by SBT:
George,
How do I determine if the scope is tourqed? I rechecked all the screws, all were tight and the scope did not appear to have moved. Yes, I did change magnifications from 1.5 at 25 yards to 5 at 100 yards. The scope is a Leupold 1.5-5x20 standard duplex. I traded for the scope but it appears as new. I do not have another scope to try and at $100 plus for a box of shells, this could get expensive. Any quick ways to tell if the scope is good?

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Do you have a bore-sighter? If so, secure the rifle in a stable rest; while seated and looking through the scope at lowest magnification, note the location of the scope's cross-hairs relative to the position of the bore-sighter's reference cross-hair.
Then turn the magnification up; if the scope's reticle moves significantly, you have a problem.

As for possible torque, that may be due to the rings being tightened too much, the rings not being aligned, or even the scope mount holes in the receiver not being true.
If you didn't take steps to mount the scope so that it is stress-free, remove it and try again, this time using scope tube alignment bars (or a 8"-12" piece of bar stock turned to the same diameter as your scope tube), some lapping compound, and judicious tightening of the scope ring screws.

Search this site for more details - try 'ring lapping' as your search argument.

George

OK, I think I've got it.

I'll check my scope with a bore sighter and if all is well, back to the range.

I think what I've lerned is that when I tried for "dead nuts" at 25 yards, I may have over adjusted. This did not become noticable until I shot at 100 yards.

I need to now zero at 100 yards, or 1" high at 100, then go back to 25 yards and if the scope is OK, I should be close to being on.

Do I have that right?

Using Norma's ballistic calculator, complete with graph and sight line heights. If you sight in a 416 rigby with a 400 grain bullet @ 25 yards using a scope 1.5" above the sight line. The bullet will impact 2" high at 100 yards.

SBT, you are correct.

Have you chronographed your loads? I have seen a few very different muzzle velocities coming out of Rigby's depending on who is doing the loading and the individual characteristics of the rifle. This may have an influence on your results.

there is nothing wrong, it all equates, what vapodog and others told you is correct...Sight the gun for 100 and then check the 25 yard, you need to know where it shoots a various ranges, you may want to plug a buff in the eye up close.