I'm interested in knowing what the difference is and what's commonly likely to cause both. POI shift could be the barrel or scope shifting correct? Especially if it's a significant shift but it's consistent from shot to shot. Is loss of accuracy where you're seeing a lot of fliers that are clearly not going where you aim? And are the fliers most likely fowling in the barrel or perhaps damaged pellet skirts? To be certain, I do not spend time weighing or washing my pellets. I just shoot for enjoyment and sling a lot of lead on the daily. Typically, I blame my shaky hand for any outliers. However on a couple of occasions, I did have a few pellets that just out of the blue veered left and up or left and down for no particular reason. Additionally, when I cleaned my barrel the POI shifted a day after I rezero-ed it.
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POI shift vs loss of accuracy
- Thread starter damageINC
- Start date
poi shift that maintains accuracy would not be a shifting scope in my opinion. Its hard to maintain good accuracy if the scope is moving around. Poi shift can be caused by temp differences causing a change in the amount of pressure a stock or something similar could be applying to a barrel or shroud. Also a temp change could cause a shrouded barrel to shift due to two different materials used between the barrel and shroud or other mounting components that increase or decrease size faster than each other as temp changes again causing a stress point or pressure point. Pressure changes in the air tube or bottle of a pcp can also cause poi shifts depending on the design. Loss of accuracy can include a poi shift or the poi can stay the same.
Example of the difference between poi shift and accuracy loss :
POI shift would be a rifle that consistently shoots .5 groups and is zeroed to hit the bullseye one day starts hitting 1" left but maintains the .5 group size. Then starts to hit 2" high but again its still shooting .5 groups.
Accuracy loss would be the same rifle is zeroed and shooting .5 consistently. After 15 shots the center of the group is still on the bulls eye but the groups start growing from consistent .5 groups to 2" .
I hope that makes sense.
Cleaning a barrel can cause a poi shift from where it settled when it was seasoned. Not a big deal you just have to learn how the rifle likes its barrel for best accuracy and what it does when it gets cleaned. The random flyers could be bad pellets or a magazine thats damaging pellets. You could also have a burr in the breach end thats causing some minor damage to pellets causing flyers. Flyers could be a barrel that needs cleaned but my experience is just a loss of accuracy not really flyers. A flyer is a shot that lands outside the normal pattern of the rest of the group. Example of flyers is a 5 shot group that has 3 or 4 shots that measure .7 but the other one or two shots are 1" out side that group.
Example of the difference between poi shift and accuracy loss :
POI shift would be a rifle that consistently shoots .5 groups and is zeroed to hit the bullseye one day starts hitting 1" left but maintains the .5 group size. Then starts to hit 2" high but again its still shooting .5 groups.
Accuracy loss would be the same rifle is zeroed and shooting .5 consistently. After 15 shots the center of the group is still on the bulls eye but the groups start growing from consistent .5 groups to 2" .
I hope that makes sense.
Cleaning a barrel can cause a poi shift from where it settled when it was seasoned. Not a big deal you just have to learn how the rifle likes its barrel for best accuracy and what it does when it gets cleaned. The random flyers could be bad pellets or a magazine thats damaging pellets. You could also have a burr in the breach end thats causing some minor damage to pellets causing flyers. Flyers could be a barrel that needs cleaned but my experience is just a loss of accuracy not really flyers. A flyer is a shot that lands outside the normal pattern of the rest of the group. Example of flyers is a 5 shot group that has 3 or 4 shots that measure .7 but the other one or two shots are 1" out side that group.
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well you got a thingamabob being smacked by a hammer to release air .. it just wont go as planned every time lol ... a good one thats missed alot on with 'shift' is the kewl barrel band thats cinching the barrel down tight .. it disheartening i know, but do realize that if its cinched to an airtube, its very likely that airtube, no matter how robust, will be changing shape and position on its way from 3000psi to 2000 ..
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Thanks. Yeah the fliers were unlike what I normally experienced. It was like a single shot going 2 inches off center with no repeatability and no rhyme or reason. I'm used to me pulling a shot and it being about a half inch off, but these were like they had a mind of their own.
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Lots of potential causes for flyers. If you do not focus the diopter lens, the one closest to your eye, well your head position can cause you to aim to a slightly different point, for instance. The solution is to focus the diopter so you have to look through the same point each time. That also makes the recticle more clear. Varying wind moves pellets more than I thought it did, even at backyard distances. I was surprised when I messed around with chairgun assuming a 5 mph wind. I think some pellets are damaged and that causes some of my flyers. Most airguns have barrels that are inside a shroud with spacers separating the two. If that small amount of pressure changes, it can cause a flier or a POI shift. Fliers open up groups messing with accuracy.
I don't think I have ever traced a POI shift to the gun. But I have traced it to the scope. I think the relatively inexpensive ($100-$300) scopes I use need to settle in after adjustment. I am shooting the two PCPs I intend to squirrel hunt with daily to make sure I have them well zero'd. My P35-22 started clipping yesterday and that caused a big POI shift but otherwise I am making small adjustments as they settle. Just a few clicks some of which might be me messing with a wind related move in POI. I got rid of a bug buster (sent it in for service and it was never returned) that would shift POI an inch or more daily. I think my West Hunter 4-16 did this one time but it has not repeated so it might be me or something else. Lately it's been dependable. My fine tuning of the scopes on my guns is messing with precision, it does not affect accuracy. In low wind these guns will shoot pellets no more than 1/4 inch apart at 25-33 yards so the accuracy is fine for hunting but I also need them to put the pellet where I am aiming. I want the zero to be 38-40 yards and I can't shoot at that range in my yard so I want to see POI on point of aim at 25 yards and about 1/8 higher than point of aim at 33 yards.
I don't think I have ever traced a POI shift to the gun. But I have traced it to the scope. I think the relatively inexpensive ($100-$300) scopes I use need to settle in after adjustment. I am shooting the two PCPs I intend to squirrel hunt with daily to make sure I have them well zero'd. My P35-22 started clipping yesterday and that caused a big POI shift but otherwise I am making small adjustments as they settle. Just a few clicks some of which might be me messing with a wind related move in POI. I got rid of a bug buster (sent it in for service and it was never returned) that would shift POI an inch or more daily. I think my West Hunter 4-16 did this one time but it has not repeated so it might be me or something else. Lately it's been dependable. My fine tuning of the scopes on my guns is messing with precision, it does not affect accuracy. In low wind these guns will shoot pellets no more than 1/4 inch apart at 25-33 yards so the accuracy is fine for hunting but I also need them to put the pellet where I am aiming. I want the zero to be 38-40 yards and I can't shoot at that range in my yard so I want to see POI on point of aim at 25 yards and about 1/8 higher than point of aim at 33 yards.
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