POI Shift Between Ammo Types?

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coleman1495

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I recently got a CZ 457 in 22lr. It is the sporter barrel/synthetic stock model.
It shoots pretty decent. I’ve tried a bunch of types of ammo and everything groups okay.

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”.

Question is: Should I be looking at the stock or the barrel to fix this issue?
 
Find what the gun likes, stack it deep and sight it in.
Or are you hoping to pour random brands of 22lr into a bowl and shoot sub moa?
 
Yes different brands will shoot at a different POI, but 3” is excessive.

Definitely not “hoping to pour random brands of 22lr into a bowl and shoot sub moa”.
Would be nice if it was at least close enough to shoot groups on the same sheet of paper.
 
coleman1495 said:
Question is: Should I be looking at the stock or the barrel to fix this issue?
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As long as your intra-ammo groups are ok I wouldn't worry about the barrel. I don't know what other rifles you've had but the CZ's have a fairly tight bore. Don't know if that would amplify poi effects but it might. I learned about the tighter bores when I bought my first CZ and tried to bore sight it. The laser bore sighter wouldn't fit into the bore. At all. Not even close. All my other rifles it dropped in with play, I needed the little 22lr arbor to make them snug.
 
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Pocisk said:
As long as your intra-ammo groups are ok I wouldn't worry about the barrel. I don't know what other rifles you've had but the CZ's have a fairly tight bore. Don't know if that would amplify poi effects but it might. I learned about the tighter bores when I bought my first CZ and tried to bore sight it. The laser bore sighter wouldn't fit into the bore. At all. Not even close. All my other rifles it dropped in with play, I needed the little 22lr arbor to make them snug.
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Interesting, the tight bore theory might explain it. Sounds like a good reason to try an IBI
 
Different brands and varieties of ammo = likely differences in muzzle velocity = differences in POI.
That is only one of the variables. What you are experiencing seems totally normal to me.
Gilbert
 
Going from 1050 to 800fps is around 3"....since you didnt mention all the specifics i imagine this is it. Also could bee shooting 30 to 60gr projectiles..... Either find more info and use that to impact what you should "expect" or just deal with it.

Paper is 11". Your shift is allegedly 3". How are you not getting it on the same sheet...
 
Different ammo types but you don't post anything about bullet weights and muzzle velocities. If the ammo that shoots 3 inches different from most of the others is some sort that is wildly different for weight and velocity then it's perhaps not unreasonable.

I tested my Savage MkII with a big variety of ammo. Some grouped very neatly but all grouped at least decently at 50 yards. But each ammo type shot the groups over about a two inch vertical zone and even up to a good half inch in windage. That's the GROUPS, not individual rounds.

I also tried some CCI Quiet for giggles. It shot out of the range of the other groups by an inch different from the next closest ammo type. And a very tidy group to boot. But at only 810 fps printed on the box not a lot of long distance carry.
 
Jahnj0584 said:
Going from 1050 to 800fps is around 3"....since you didnt mention all the specifics i imagine this is it. Also could bee shooting 30 to 60gr projectiles..... Either find more info and use that to impact what you should "expect" or just deal with it.

Paper is 11". Your shift is allegedly 3". How are you not getting it on the same sheet...
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Nah they are both 40gn going similar velocity.
Paper has 5 diamonds so 3” can be off paper.
 
coleman1495 said:
I recently got a CZ 457 in 22lr. It is the sporter barrel/synthetic stock model.
It shoots pretty decent. I’ve tried a bunch of types of ammo and everything groups okay.

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”.

Question is: Should I be looking at the stock or the barrel to fix this issue?
Click to expand...

So far the info you have presented does not indicate any "issue" to "fix". You have not given us sufficient data to offer any opinions for trajectory differences. Primarily, you have not provided the ammo brand names and the muzzle velocities (V0) printed on the box, or V0 on spec sheets from their respective websites. The 3 inch variance in POI's between ammo brands is totally normal based on differences in V0 across many brands.

Note that the V0 listed in the brands spec's may not be the actual V0 of that lot of ammo. That number they list is an average of an average. Take with a big grain of salt. Eley is one of the few companies that lists the variance to be expected per brand. For example in Eley's subsonic line, Eley Team is listed at 1040 to 1085 fps, and Eley Sport is listed at 1000 to 1090 fps. That's a potentially big variance depending on what lot you ended up with. Add to that different bullet shapes, different lubes, different brass, etc, and it can account for alot of POI difference between ammo brands.

Comparing subsonic to supersonic would account for large POI differences, but I am guessing you are well aware of these and have separated these for testing? Its been a while since I shot supersonic ammo, but I recall it had significant POI shifts from the subsonics, not just in elevation, but also in windage.

If you could please list the various brands of ammo and their V0's that you aye are the big differences, then maybe folks here might be able to theorize about the magnitude of the group POI's.
 
The biggest shift in my experience was CCI MiniMags . . . Round nose and Hollow points.
At 100 yards the round nose was grouping 2".
The hollow points were 6" left and a six inch group.
 
coleman1495 said:
Sounds like the barrel is the first place to look. I know what my next big ticket purchase will be.
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It's the ammo. From my reading, you're the only one posting in this thread who thinks the barrel is the issue.

If you want to buy a new barrel, go right ahead. But don't expect it to improve the situation you're describing - You'll just have different POI shifts, not necessarily "better".
 
grauhanen said:
It's the ammo, not the barrel. It's much more straightforward to make barrels more alike than ammo, especially inexpensive ammos.
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Unless by the ammo you mean to shoot the same type so I don’t have a POI shift.
Not sure whats confusing folks here. I’m getting abnormally large POI shifts between ammo types.
No its not between drastically different types either.
 
coleman1495 said:
Unless by the ammo you mean to shoot the same type so I don’t have a POI shift.
Not sure whats confusing folks here. I’m getting abnormally large POI shifts between ammo types.
No its not between drastically different types either.
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You're asking for help, but not liking the answers you like.

Have you checked the barrel for free floating, any screws loose? Have you played with action screw torque? Is your scope a issue?

If you shoot a group with ammo A and then ammo B, if you switch back to A. Is there a repeatable POI change.

Or done anything prior to eliminating that it's the barrel?
 
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