POI Shift Between Ammo Types?
- Thread starter coleman1495
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This time of year people re-zero at matches because of the POI shift just from change in temperature....
Start shooting at -2 at 8am and +20C in the afternoon... see what happens with rimfire at 100-300m.
Different manufacturing 'lots' of the same brand/model ammo have had different POI for me...
Start shooting at -2 at 8am and +20C in the afternoon... see what happens with rimfire at 100-300m.
Different manufacturing 'lots' of the same brand/model ammo have had different POI for me...
82 posts and OP still hasn't listed what ammo and velocities he's using.
You can spend a week making something by hand and post it here and be lucky to get 3 comments.
Who knew being daft was such a good way of getting attention.
You can spend a week making something by hand and post it here and be lucky to get 3 comments.
Who knew being daft was such a good way of getting attention.
coleman1495
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I see you really struggle with reading comprehension.
coleman1495
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That’s because its an irrelevant question. I’m not new to this, the shifts I’m seeing are much more than expected. Thats all you need to know.
Yes you are. This is exactly what you've described.
That's still an extreme spread.
Dude, other than you sucking at shooting, it's the ONLY variable that's changing. Do you honestly think the barrel changes depending on the ammo? That's downright retarded to suggest.
What you need to know and clearly can’t comprehend is that your expectations bear no influence to reality.
That may help attract attention.
But I'll bet the replies would be as or more numerous and of a different tone if a poster asking the same question had the name "Shooter Girl" or something similar.
To be more serious, however, I think part of the problem here is that the OP hasn't articulated the problem particularly well. If so many readers misapprehend the problem described by the OP, he should consider that he has room for more clarity of expression.
Here's what he said: What I don’t understand is why I’m seeing a huge difference in POI between ammo brands. I’m seeing 3” shift at 50yds just from changing ammo. I normally see a POI shift but never that huge. On my other 22lr rifles I’d see maybe 1-1.5”.
Is it that he gets a 3" difference in POI regularly whenever he switches to another make or type of ammo? Did this happen one time? Does it happen over repeated testing?
If it's once, it's hardly worth asking about. If he's compared two ammos repeatedly and just as repeatedly observed the second ammo having a big shift in POI, then it may be worth considering.
Do readers know if the OP has checked barrel retention screw torque to ensure they are as they should be?
The OP can rest assured that readers of this thread are just as frustrated as he says he is. Of course they may be frustrated for different reasons.
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Is a good point in Post #93 - about how the barrel is fastened / mated to the receiver - I would think if "wobbly" or "mis-torqued" or "not square" - that would produce different results from different ammo? - pressure rise, vibrations, etc. Maybe just dismantling the rifle, and then re-assembling it to spec - might make a difference?? Straight up swap out barrel or stock as options, might ignore the attachment of any particular barrel or stock - to the receiver. And, as per earlier posts, is the phenomenon a statistically valid thing - or was it a "one time" occurrence? Is it repeatable? Do you clean out previous fouling and then re-condition that bore with the new stuff, as part of the testing?
There is an elderly Mauser sporter here that I am playing with - so centre fire, not rim fire, but I am guessing the principles are similar?? I removed that 100 year old rotted out barrel - set that receiver in a mandrel on my lathe - and that receiver front face was many thousandths out of square - likely within some spec back in the day - likely viewed as perfectly adequate rifle over the years - but not what this Kuhnhausen manual suggest for assembling for "best results". My intention is to install a new McGowan barrel - I want to give it the "best chance" - so got into fussing about receiver face "square" to receiver barrel threads - bolt race to be square and co-axial, seating of the locking lugs, etc. Job not close to be finished - I suspect is one thing to go from 6" groups to 2" groups - then much more subtle to go from .6" groups to .2" groups.
No doubt there will be difference of opinion based on past experiences - for some, trying to use higher end target or bench rest rifles for score in competition - a .25" deviation will be a huge thing. For others, perhaps 1" variation at 50 meters not even noticeable for their kind of shooting.
There is an elderly Mauser sporter here that I am playing with - so centre fire, not rim fire, but I am guessing the principles are similar?? I removed that 100 year old rotted out barrel - set that receiver in a mandrel on my lathe - and that receiver front face was many thousandths out of square - likely within some spec back in the day - likely viewed as perfectly adequate rifle over the years - but not what this Kuhnhausen manual suggest for assembling for "best results". My intention is to install a new McGowan barrel - I want to give it the "best chance" - so got into fussing about receiver face "square" to receiver barrel threads - bolt race to be square and co-axial, seating of the locking lugs, etc. Job not close to be finished - I suspect is one thing to go from 6" groups to 2" groups - then much more subtle to go from .6" groups to .2" groups.
No doubt there will be difference of opinion based on past experiences - for some, trying to use higher end target or bench rest rifles for score in competition - a .25" deviation will be a huge thing. For others, perhaps 1" variation at 50 meters not even noticeable for their kind of shooting.
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coleman1495
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Have you ever seen me shoot?
If you took 2 seconds to understand the question you’d realize that claiming bad marksmanship is absurd. The groups are fine
Are you just being obtuse and annoying or is your reading comprehension really that bad?
I don't need to see you shoot for my comment to not be obtuse. You sucking at shooting is a variable. If you've eliminated that variable, the only other variable is the ammo. See how that works? See how that's not obtuse? The gun hasn't changed. the target distance hasn't changed. I can only assume by your lack of actual evidence that the day hasn't change. The irony in your reply is clearly lost on you, and your compression of my statement is also lacking. This is process of elimination at its most basic form. "I've observed a change in my POI. What did I chance from my last group? The ammo. If I change ammo back, does my POI return to the original group? Yes. This ammo causes X amount of POI shift. The end." You either accept that shift and adjust for it, or find another ammo that doesn't shift as much. It couldn't be any simpler.
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Says the groups are fine. Not a loose barrel. Gun is fine.
coleman1495
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That may help attract attention.
But I'll bet the replies would be as or more numerous and of a different tone if a poster asking the same question had the name "Shooter Girl" or something similar.
To be more serious, however, I think part of the problem here is that the OP hasn't articulated the problem particularly well. If so many readers misapprehend the problem described by the OP, he should consider that he has room for more clarity of expression.
Here's what he said: What I don’t understand is why I’m seeing a huge difference in POI between ammo brands. I’m seeing 3” shift at 50yds just from changing ammo. I normally see a POI shift but never that huge. On my other 22lr rifles I’d see maybe 1-1.5”.
Is it that he gets a 3" difference in POI regularly whenever he switches to another make or type of ammo? Did this happen one time? Does it happen over repeated testing?
If it's once, it's hardly worth asking about. If he's compared two ammos repeatedly and just as repeatedly observed the second ammo having a big shift in POI, then it may be worth considering.
Do readers know if the OP has checked barrel retention screw torque to ensure they are as they should be?
The OP can rest assured that readers of this thread are just as frustrated as he says he is. Of course they may be frustrated for different reasons.
The shift in POI is consistent. If I switched ammo, I could write down scope adjustments and set my new zero.
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- Western Manitoba
Perhaps to understand, barrel might not "feel" loose? Looking at a Ruger 10-22 here - barrel has tenon that slides into aluminum receiver, then held with "C-clamp" thing with two screws. If it slides in or out - can not be same size - if perfectly same size will not be able to move by hand? Then, if one clamp screw torqued to 30 inch pounds and other screw torqued to 50 inch pounds - barrel will not be loose - but would think is very different tension on one side versus the other side - I suspect is that "tension" difference is what shows up when the round is fired?? Is my guess why Kuhnhausen manual and other references are looking for "squared" receiver face with a screw in barrel - presumes, I guess, that the barrel shoulder is also square to the threads - so that tension is even all around that barrel to receiver contact. Perhaps worth to investigate before a spend on replacement stuff?
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Just stick to drag shows.. shooting isn’t your thing.
You said “What I don’t understand is why I’m seeing a huge difference in POI between ammo brands. I’m seeing 3” shift at 50yds just from changing ammo.”
As I said - imagine being surprised that using different ammunition generates different results.
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