Point of impact shifting 3-4 inch groups at 100 yds rifle shot exc. prior to this. tried a good tip hump, tried free floating, and problem still exists.

You need to check the seals and valves on the pump to make sure that they are all in good shape and that there is no scoring in the cylinder.

No, that doesn't sound stupid. It's always a good idea to get all the information before using firearms and their accessories, and I'm happy to help:

The large knob on top of the scope is the rheostat, which is used to turn on the red dot, and adjust the brightness. It can be adjusted from "1" (dimmest) to "11" (brightest). You'll have to be looking straight down the scope to see the red dot, since it is only visible when you're aiming. If you turn on the scope to the brightest setting, and you look through like you are aiming, and the red dot is still not there (or very dim) then you probably need to replace the battery. It uses a 3 Volt coin-style lithium battery, type 2032. Unscrew the battery compartment on top of the rheostat and put the new battery "+" side up. Then replace the battery cover, and you should be good to go. Turn off the scope when you're done to save the batteries.

Since you bought the rifle with the scope already installed, it's probably already sighted in, or pretty close to being sighted in. Adjusting the windage and elevation on the red dot scope works just like other rifle scopes. The knob on top moves the point of impact up/down, and the knob on the side moves left/right. For this model, each click of adjustment moves the point fo impact by 1/2" at 100 yds, 1/4" at 50 yds, or 1/8" at 25 yds.

Be safe, and have fun!

if your scope is shooting low and you dont wont to buy a new set of mounts the only way to lift the point of aim is to pack out the eye end of the scope mount with 35mm film or a soft type of shim that wont scrach your scope i use 35mm film at its mostly water proof but there are other shims that do the same thing put about 25th of an inch under the eye end between the scope mount and the scope this will lift the "bell end" up and lower the point of aim there by rasing the impact point of your bullets dont over do this idear as if you go to far you wont get the turrets to drop the point of impact and you could also bend the scope, but 25th of an inch is not a lot but its over 10 inches at 100 yds with a .22 rim fire rifle
good luck shoot safely and good hunting

the front ring is for adjusting point of impact at a given range,,,its called a "parallax ajustment" it corrects for the scopes inaccuracies over its full range say from 10 yds to 100 yds there a bit of a pain on a hunting rifle as you need to focus them every time and that slows down your shooting, when only a snap shot will get the kill you cant wate to mess about focusing the darm scope so i never use them on my rifles,,unless im target shooing,, or im snipping when i have time to take my shot,,,
(a head shot only!) only a parallax scope is spot on aim from 10yds to infinity

this is a common fault with fitting cheep mounts on your rifle,,
a nikon scope is realy for "air rifles" but having sead that there very strong scopes, i have 4 of them all fitted on full bore rifles,,308,(7.62) .303 british enfield, .22-250 and a 357 mag rifle? and none of them have shook apart yet! and i found that on a full bore they do shoot low,,,to get over this problem you could change the mounts to the ajustable type witch is pricy,,or a cheep way out is to pack the bottom of the rear scope mount out with a strip of 35mm film,,(the rear being the end you look throw),you only need to life the rear end of your scope 25th of an inch to rise its point of impact by 6" inchs at 100 yds as the nikon scope is one click (1 thou of an inch) = 1/4 of an inch at 100 yds so 25 thou will raze it by 6.25 inches (- bullet drop!) just undo the scews that hold down the rear of the scope and slip a bit of old 35mm film under the scope then nip the scews back up again and try it out,,,if its still low put in a bit more packing,,,but you can only get about 4 bits of film in before its likley to bend the scope tube!!! mind you with 4 bit under it you will be shooting at the moon??? its much cheeper that ajustable mounts,, all my scopes are packed out like this and they dont creep or slide or loos point of aim even after 300 rounds in a day?

The Bushnell 3-9X40 has been around for quite some time in several forms, but it is pretty standard to set it like any other scope.

With the gun resting solidly on sand bags or something like a Lead Sled, shoot at a target with a 1" grid on it. Those targets are a free download at http://targetz.com/, but you have to browse to find them. Targets No: 10049 or 10058 are both usable, if you can see a 1" aiming point with a 9 power scope at 200 yards.

With a known point of impact (POI) at 200 yards, you can move the POI to where you want it (inside the caps at the center of the scope, there are adjusting screws or slots). The norm is 1/4" per click (the adjuster can usually be felt to click) at 100 yards or four 1/4" clicks for an inch. At 200 yards, the adjustment will be twice what it is at 100 yards or 1/2" per click.

Make your adjustments, using the grid on the target to tell you how many inches it needs to move, and shoot the target again to confirm the adjustment is correct. It's pretty standard to shoot at least a three shot group to ensure the bullets are reasonably close to each other.

Another method is to set the POI at a certain number of inches high at 100 yards and assume it's right at 200 yards. If the mid range trajectory, for your cartridge, at 200 yards is X inches high at 100 yards, you can set your POI to that X inches high and be pretty close at 200 yards.

Mount the rifle with the scope and make a mark on the backstop right where the crosshairs are pointed at

Shoot several times, several shots will surley jolt the scope some.

If the crosshairs have moved much past your mark then this would indicate the scope is the issue.

If the crosshairs are still pretty well centered to the mark, its not the scope.

If at the same time your grouping looks terrible, and your scope still is on the mark, and the gun is WELL mounted, then the issue is with the accuracy of the rifle.
Make sure the rifle is mounted good for this to ba accurate .
Hope this helps

sounds like it could be the scope more than any thing but shoot at 100 yd 5 shot group and see if it groups if if shots dance around on target make shure your mounts are tight there is time that companys send screws for the mounts that are to long for the holes that are taped in the gun the mount mite feel tight but could have play yet witch make your gun not shoot well you could also try setting the scope on 4 power shoot a shot at 50 yards then crank it up to 9 power shoot a shot if bullet impact moves it is the scope hope i helped ya out and good luck

Ja, it's 1/4 M.O.A, so at 25 yards/meter it'll be ca 3 inches. You may have gone in the wrong direction. That is, if it was 3' high, and you went another 3 higher then you'd be at the top of the paper. Probably you've got it figured out by now.

The easiest, fastest, cheapest way to zero is with a rifle rest you can clamp your scope into, or alternatively somehow immobilize your rifle some other way. You take a shot, at 25 yards or so. It makes a hole. You now immobilize the rifle, via your rest or heavy sandbags, with the scope pointing exactly where you aimed before. You now, carefully and without moving the rifle/scope off of the point of aim, dial your reticle to point at the actual bullet hole. Your next shot will be at your point of aim now. So you just put it at the right height above your point of aim at 100 yards now.