Different POI at different powers on scope.

[2footroper]

OK guys and gals. Here is my problem. I had gotten a CVA Accura muzzle load rifle as a Christmas gift 2 years ago and never fired it. A friend of mine invited me on a last minute muzzle load only deer hunt in N.E. Nebraska so I accepted. I had mounted a Nikon 2 X 7 Pro Staff Shotgun scope with a BDC retical on the rifle but never shot it until last week wednesday. This rifle is far more accurate then I expected shooting 1 1/4 MOA. I sighted the gun in at 7 X shooting 3 1/4" high at 100 yards to be dead on at 150 according to the ballistic chart for my power belt bullets. Ready to go hunt. Fast forward to Tuesday morning. Sitting in a nice heated deer blind I see that there is a substantial amount of timber and cedars so I opted to set the scope to 2 X so I might be able to pick up a deer quickly in the woods. The furthest shot would be 95 yards so 2 X would be more then enough. Shortly after I get set up I see two bucks approaching from my right. First is a small 2 year old. Next is a very healthy 6 or 7 year old 9 point with a very respectable rack. They turn and drop down an incline of 45 degrees and get to 85 yards. There are alot of rubs and scrapes and the area is open enough that the 9 point gave my a classic broadside shot. I was shooting down that 45 degree angle and I opted to put the crosshairs on the deer for a heart shot thinking the bullet is going high already and shooting down will only add to the height. I don't like spine shooting deer. Too much tenderloin dammage. This gun has an ammaizing trigger. The rest out the window is rock solid. Breath, Squeeze and pow! I see the round impact just under the deer. I'm thinking maybe the bullet passed through and that is what I saw. No such luck. Clean miss. How can this be. I can't miss from that scenario but in fact I did. Now I'm beating myself up trying to think what I did wrong. We get back to the cabin later that morning and I can't take it. I take an empty box from a case of soda and take it out to 60 yards. Load the gun and crank the scope to 7 X. Pow! About 3" high. What in the heck is going on. Perfect. Then I remembered I had the scope set down to 2X. I crank it down, reload and pow. I don't see the hole. I walked up to the box the the bullet shot 2" below my point of aim!!! Has anyone ever heard of anything happening like this before? Sorry for the long story but does anyone have any thoughts on this at all? Thanks in advance for any help.

[LoneWolf]

Is it a second focal plan scope? If so then the crosshair markings will be different depending on magnification level. This is the most likely case for this to happen and why I only use first focal plan or FFP variant optics.

[2footroper]

I'll have to look it up. I was thinking maybe one of the optics is not cemented in straight and square or something. Thanks for your suggestion.

[quickkillaught6]

I'm going to ask the questions I would ask myself given the same circumstances. First off yes as lone wolf said you will have some deflection in power range with a SFP but 5"s is pretty excessive at 60 yards. I'd look into the scope sounds dinked up, if the gun groups and shoots POA POI, you never said if it's a fouled barrel or cold bore shot or if the gun groups 3-5 shots well. I need more info to condem the scope. Is this a cold bore shot on 7x and the second shot on a dirty barrel at 2x? My optima shooting 100 (777) pellets and a 295 green skirt power belt shoots lights out after the first shot always carried it fouled and spit patched between shots but the cold bore shot was anywhere from 6-12"s from POA tell us more

[LoneWolf]

5" is about right on going from 7x to 2x. Considering it's an MOA scope aswell.

[2footroper]

I'm going to ask the questions I would ask myself given the same circumstances. First off yes as lone wolf said you will have some deflection in power range with a SFP but 5"s is pretty excessive at 60 yards. I'd look into the scope sounds dinked up, if the gun groups and shoots POA POI, you never said if it's a fouled barrel or cold bore shot or if the gun groups 3-5 shots well. I need more info to condem the scope. Is this a cold bore shot on 7x and the second shot on a dirty barrel at 2x? My optima shooting 100 (777) pellets and a 295 green skirt power belt shoots lights out after the first shot always carried it fouled and spit patched between shots but the cold bore shot was anywhere from 6-12"s from POA tell us moreAll shots with clean cold bore. From first shot ever fired in this gun on till now. I have always let the barrel cool between shots and run a patch through. Shooting White hot 100 gr. and powerbelt 250 gr aerolite Aero Tip bullets. The gun was sighted in on a lead sled straped down for consistancy then shot off bag rests. Never any variant in shot groups. It groups as stated 1-1/2" or better at 100. Every time, but it was always at 7X. If weather permits tomorrow I will do this again on the sled at both 7X & 2X to confirm my suspitions. I did it at the cabin as stated but once more under more controlled conditions should tell the tail.

[Jamie]

POI changes due to magnification adjustment is not unusual. The amount you experienced is on the larger side but still possible depending on the scope. About three weeks ago I went through this same scenario with a gentleman at the range. Every shot on 9x was exactly where it needed to be, drop it to 3x and it would shoot high about 3". It is most likely the scope moving the reticle that much when you change the magnification, some may be the fact that on 2x you may have a harder time holding true center.

[quickkillaught6]

2foot keep us posted on findings, I know a lot of people love the lead sled but it is utter hell on scopes. 5"s is just way too much deviation for any scope period. I've got a 3-9x40 OLD leupy on my optima and haven't experienced this nor in my cheap Tasco so I will definitely follow this to see where the culprit lies here hopefully you can get it figured out soon and get back to hunting. Let us know and good luck

[foxx]

I respectfully disagree that sfp scope changes poi when changing magnification due to the design. If it does so, it is defective.

FFP is good for allowing one to use multiple VERTICAL holds for various ranges and to be able to do so consistently at different power settings, that much is true. However, if you are simply relying on a traditional reticle, or the CENTER of a multiple range reticle, it should not matter which power setting you are at.

Cheap variables are known to have this problem, but not a quality variable.

[D.ID]

^^^^^WHAT HE SAID^^^^^^^
Everyone always pimping that overrated ffp is fine by me.
Everyone trying to claim sfp scopes don't work because of varying subtentions which are irrelevant if the shooters not even using them and admittedly: it is driving me nuts lately.
Not everyones a reticle junkie and even those of us that are: using the subtensions on a sfp is not complicated unless your brain dead .

[2footroper]

Well I bench shot the gun today and the result is the same. 5" difference in hit. 4" high at 7 power and 1" low at 2 power at 60 yards. Repeated this twice with the same results. Contacted Nikon and they want the scope so I'm shipping it tomorrow. We'll see how this works out and I will post the results. There is NO WAY there should be even an inch in variation in POI at that range just by changing the power setting. What would be the advantage of having a variable power scope at all. I don't care what focal point it is. Thanks for all the input fellas.

[dcloco]

2footroper - check your personal message please. Top right corner of the page - click on the arrow pointing down next to "notification".

[2footroper]

dcloco I replied to your message.

[darkker]

1) I respectfully disagree that sfp scope changes poi when changing magnification due to the design. If it does so, it is defective.

2) FFP is good for allowing one to use multiple VERTICAL holds for various ranges and to be able to do so consistently at different power settings, that much is true. However, if you are simply relying on a traditional reticle, or the CENTER of a multiple range reticle, it should not matter which power setting you are at.

1) if the poi alone changes, the tin can is broke; throw that pos in the ocean. What does change with it being SFP is the BDC, what power is the adjustment meant to work on? Is the OP's ammo ACTUALLY performing (speed, BC, etc) identically to what the reticle was calibrated to?
2) The virtue of a FFP has nothing to do with "holds". Adjustment, and ranging at any power is the virtue. The distance between mils is always the same at any power, and so the adjustment needed is always the same.




^^^^^WHAT HE SAID^^^^^^^
Everyone always pimping that overrated ffp is fine by me.
Everyone trying to claim sfp scopes don't work because of varying subtentions which are irrelevant if the shooters not even using them and admittedly: it is driving me nuts lately.
Not everyones a reticle junkie and even those of us that are: using the subtensions on a sfp is not complicated unless your brain dead .


Like many I wanted to get into LR shooting, so I bought a mil-Dot sfp scope. The turrets unfortunately are 1/4moa, also not uncommon to have mismatched turrets/reticles; look at most of nightforces lineup. A mil-dot and moa adjustments takes a wheel, or a calculator to convert the answer. Being SFP, once I change the power, there is another calculation.
Now that I understand what I'm doing a little better, fast forward to my Primary Arms scope. FFP, mil-mil. So mil-dot reticle, 1/10 mil turrets. This means at ANY power, the distance between my dots is one mil. My turrets move in 1/10 mil clicks.

I don't think I'm brain dead. But from my story, which is not unlike many others; one way is a lot of referencing or calculating, the other is a lot of shooting. For a shooting enthusiast, I would say choosing the method that prevents maximum shooting is brain dead.

[D.ID]

One moa of adjustment is 1 moa of adjustment at 6x or 24x regardless of reticle subtentions 1is1 2is2 3is3 22.5 is still 22.5.
Mil reticles range at any magnification in ffp and only a specific magnification on sfp.
Turrets adjust in moa or mils depending on model regardless of focal plane.
You seam to constantly confuse all scope reticles as a BDC which is not necessarily there intended purpose.
All reticles can be used for correction.
My moa turret adjusts to corect for my shots.........................
My mil dot reticle is used for ranging...................................Two separate functions......and one of them that I rarely use.
NOT A BDC............I dial in my shots, So I do not care if one mil threw the scope is one mil unless I am ranging. The rest of the time it does not matter. If I shoot and hit one dot (NOT A MIL) because my scope mils at 12x and I am at 24x but it DOES NOT MATTER because I hit one dot low and one dot right, if I need a fast follow up I can move POA to POI in reference to the reticle regardless of reticle size and I do not have to put up with my reticle almost disappearing on low power or being as broad as a 2x4 on high power which is the big negative of ffp.
You must be useing you reticle to measure then your dials to correct while worrying about retaining the ability to use it as a bdc at any given second in between.
.
There are some simplifications to a ffp. However they are not all peaches and cream, there is a trade off in reticle thickness. Unless your trying to use 3 methods to do 2 jobs there cons can out weigh there benefit, especially if you hardly ever use more than one (like most shooters do).
My corrections are in mils when using a mill dialed scope/ in relative inches using an moa dialed scope and the point is it does not matter!

[D.ID]

P.S. Sorry to the op for this silly pointless discussion, I am sure nikon will get you taken care of and hope to hear when they do. They make decent stuff, hope they stand behind it.

[foxx]

Darkker, I am not sure what all you were saying, but mil/mil scopes of the FFP variety allow a person to know how much to hold off for elevation and windage or make "click adjustments" by judging off the subtensions regardless of the power setting of the magnification. SFP scopes only allow one to do so at a particular mag (usually max), unless the shooter also happens to know what the subtensions are at other settings as well. That can get very confusing and requires an almost infinite number of figures to try to learn. As D' said, there are trade-offs for that, though, such as having to use larger than ideal reticles at higher magnification, and, conversely, smaller than ideal reticles at lower magnification.

If I am wrong here, I'd like a better explanation, but it's probably beyond me. :)

To the OP, your scope's POI should not change with change of magnification. SFP scopes of any quality whatsoever do not cause such a thing, unless you are trying to use any part of the reticle besides the traditional center of the main "crosshairs".

Please let us know how Nikon responds.

[2footroper]

Well boys and girls. I got the scope back from Nikon and they had to make "collimation" adjustments. I am told that is basically realigning all the optic lenses. Needless to say, I now have a Leupold scope on my CVA. Anyone want to buy a factory refurbished Nikon?