POI shift confusion

POI shift confusion

Joined: November 29th, 2010, 4:34 am

March 12th, 2011, 3:32 am #1

Alright so sighted in my gun at 15yards 5 shots through the bull every time moved targets to 25 yards shot 20 to 25 pellets seemed good, left to right wind was drifting pellets a bit so I decided to move back in to 15yards to check bang 5 shots through the same hole but... an inch high? :S now im a little confused I know that if the turret is adjusted to far out poi can shift I dont think this is the problem but if it is would it still put all 5 pellets in the same hole? wouldnt it bounce around a bit more? Second thought is change of wind moving towards me instead and lifting the pellets? had to shut'er down for the night after the last 5 shot group so now im left frustrated and confused until tommorow. Any and all responses welcomed.
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Joined: April 1st, 2009, 3:18 am

March 12th, 2011, 5:20 am #2

...phoneomenon taking place on? If you say spring-piston, well, that's pretty much says it all at first thought.

What gun?
What scope?
Same pellets during all shots?
Did you fiddle with scope adjustments at all during the different ranges?
If applicable, were trigger adjustments made during shooting?



"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."

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Joined: October 3rd, 2010, 3:22 pm

March 12th, 2011, 3:20 pm #3

Alright so sighted in my gun at 15yards 5 shots through the bull every time moved targets to 25 yards shot 20 to 25 pellets seemed good, left to right wind was drifting pellets a bit so I decided to move back in to 15yards to check bang 5 shots through the same hole but... an inch high? :S now im a little confused I know that if the turret is adjusted to far out poi can shift I dont think this is the problem but if it is would it still put all 5 pellets in the same hole? wouldnt it bounce around a bit more? Second thought is change of wind moving towards me instead and lifting the pellets? had to shut'er down for the night after the last 5 shot group so now im left frustrated and confused until tommorow. Any and all responses welcomed.
check all screws just to make sure nothing has loosened up. Barrel, scope mounts, etc.
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Joined: November 29th, 2010, 4:34 am

March 12th, 2011, 6:46 pm #4

...phoneomenon taking place on? If you say spring-piston, well, that's pretty much says it all at first thought.

What gun?
What scope?
Same pellets during all shots?
Did you fiddle with scope adjustments at all during the different ranges?
If applicable, were trigger adjustments made during shooting?



"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."

Yes it is a a Benji trail nitro piston but how does that say it all? would a broken scope still put 5 pellets through the same hole? no slippage on the scope as this was already thought through when mounting. Same pellets throughout the test (rws super point 14.5) only focus adjustment between ranges scope is the standard 3-9x40 ao. Someone on another forum mentioned that the reticle could have been hung up on some previous adjustment and after some shooting freed up and moved into the adjusted position. I hear this is a common problem on cheaper scopes (ie: center point) and some people smack the scope with a hard object after adjustment to allow the reticle to settle in position. I of course will not be doing this but I will be tinkering a little more today to see if it is infact the problem. Quick question though if I am adjusting the focus from 25 yards down to 15 and do not quite adjust it all the way to 15 say instead adjust it to 50' would this cause the problem?
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Joined: November 29th, 2010, 4:34 am

March 12th, 2011, 6:48 pm #5

check all screws just to make sure nothing has loosened up. Barrel, scope mounts, etc.
Obvious or not it is still a valid suggestion Thank you I will check all screws thoroughly. (I have been doing this but it never hurts to do it again.)
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Joined: April 1st, 2009, 3:18 am

March 12th, 2011, 8:50 pm #6

Yes it is a a Benji trail nitro piston but how does that say it all? would a broken scope still put 5 pellets through the same hole? no slippage on the scope as this was already thought through when mounting. Same pellets throughout the test (rws super point 14.5) only focus adjustment between ranges scope is the standard 3-9x40 ao. Someone on another forum mentioned that the reticle could have been hung up on some previous adjustment and after some shooting freed up and moved into the adjusted position. I hear this is a common problem on cheaper scopes (ie: center point) and some people smack the scope with a hard object after adjustment to allow the reticle to settle in position. I of course will not be doing this but I will be tinkering a little more today to see if it is infact the problem. Quick question though if I am adjusting the focus from 25 yards down to 15 and do not quite adjust it all the way to 15 say instead adjust it to 50' would this cause the problem?
...that helps.

Never "smack" the scope!! Bad idea in of itself.

I personally never had an issue with the focus changing POI. However, there is a common problem called parallax error in optics (scopes in our case). What this means is that the eye is not in plane with the cross hairs (or pointer) the same during shooting. This can happen while shooting different distances as the brain tells the head to be placed further or closer to the scope (it's an innate habit address in shooting courses). The distance the eye is to the scope needs to be consistant at all distances. A nice cheek rest on the comb helps in eliminating this problem - almost entirely.

Essentially what is happening is an optical illusion. You think you are dead on where the pellet will land.

The comment about springers is that. Springers are hard on scopes, the adjustment knobs, scope creep, hard on the lenses, hard on all screws. A scope on a springer requires more attention than that of a 30-06 rifle. However, you have a nitro piston. They tend to be a lot less recoil creative than that of the conventional spring gun.

For some more info in scopes, see the link:
http://www.pyramydair.com/site/articles/ao-meaning/

"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."

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Joined: October 27th, 2010, 2:26 am

March 13th, 2011, 2:47 pm #7

Alright so sighted in my gun at 15yards 5 shots through the bull every time moved targets to 25 yards shot 20 to 25 pellets seemed good, left to right wind was drifting pellets a bit so I decided to move back in to 15yards to check bang 5 shots through the same hole but... an inch high? :S now im a little confused I know that if the turret is adjusted to far out poi can shift I dont think this is the problem but if it is would it still put all 5 pellets in the same hole? wouldnt it bounce around a bit more? Second thought is change of wind moving towards me instead and lifting the pellets? had to shut'er down for the night after the last 5 shot group so now im left frustrated and confused until tommorow. Any and all responses welcomed.
The wind coming at you from the front will cause the pellet to slow faster, causing a lower POI. The wind from behind will be the opposite, and quartering winds will give a mixture of drift and high or low.

I sometimes tap, never smack, my rifle scopes with a light tool - like a small screwdriver - to be sure the adjustments i made take. I do this on the cheap scopes and my nikons and leupolds.

I read on one of the forums that when adjusting the objective you always have to go all the way to the lowest value and then up to the value you want so things are always mechanically the same. Its hard to explain but the post made sense.

Also, you need to try to keep the same head placement shot to shot or things will move. Its not as critical with a scope as iron sights but still makes a difference.

And it is possible that you got a bad scope right out of the box. Walmart will return/exchange anything, so take it there and get a new one if all else fails.
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