AXSR POI shift with caliber change.

[WVshooter]

Edit: To be clear, I expected to see zero shift between barrels, just trying to determine what would be considered excessive.

I just started using an AXSR after getting set up with one with several barrels of different calibers. Had a question after my first range trip and thought I'd post this since I don't have any experience with this platform and according to most threads I've found this doesn't seem like the norm.

The gun came with the .300 Norma barrel and I also got a 20" .308 AI barrel, A 27" .338 Lapua AI barrel and a 24" Stainless Proof 6.5 Creedmoor barrel.
What is considered a typical zero shift when swapping between calibers or is there even a typical outcome?
I zeroed the gun with the .308 barrel (175 FGMM) and when I switched to the .300 Norma barrel (215 Berger OTM ammo) it was less than .2 mil off the .308 zero which is fantastic.

When I switched to the AI .338 Lapua barrel (Hornady 285 ELDM) it was 9.5” low and 4.5” left. Would this be considered within acceptable limits or does this sound unusual for this rifle?
I actually thought I did something wrong installing the .338 barrel so I loosened the locking bolt and barrel and re tightened everything and the shots went back into the same group. I understand not to expect it to hold the same zero between barrels and calibers, just wondering if this is typical.

 

[Maurygold]

zero-shift means it will not move from where it was when you put the same barrel back on. Not that you can change 5 barrels out with the same zero

 

[WVshooter]

zero-shift means it will not move from where it was when you put the same barrel back on. Not that you can change 5 barrels out with the same zero

No shit. I said that in the post.

 

[moaorbust]

My AXSR barrel swaps are repeatable, per barrel, but as I change calibers they can be off .4 mil at 100 yards. Normal.

 

[WVshooter]

My AXSR barrel swaps are repeatable, per barrel, but as I change calibers they can be off .4 mil at 100 yards. Normal.

Thanks. So if you bought another caliber barrel and it was 2.7 mil off at 100 yards from your others, you'd consider that normal as well? New to this gun and caliber swapping so just trying to understand if that amount is considered normal.

 

[ma smith]

I understand not to expect it to hold the same zero between barrels and calibers, just wondering if this is typical.

The ASR submissions had to hold something like 1MOA at 100 yards. so if you see guys getting.4 or .3 with AI parts, thats probaby your expectation. If you were using 100% ai parts I personally would expect .3 to .4 and maybe worst case of .4- .6 (2moa).

The wrinkle here is you are using Proof prefits, so I don't know why you would expect that to work?

I mean the barrel's performance at that stage is Proof's problem not AI's problem.

Proof is only going to guarantee it headspaces/meets saami spaec, is safe to shoot, and is accurate (at some level). They aren't going to guarantee their barrel meets additional performance specs, unless that's clearly stated somewhere in writing.

Do you have a different expectation here?

 

[diggler1833]

I see a tenth or two in zero shift when I swap different cartridges back and forth in my AT-X. It generally takes 1-2 rounds to verify and adjust zero. This is with taking the same barrel off, and then reinstalling it again a few months later.

When I swap cartridges (6GT to 6CM etc..), I think I'm .5 left/right, and .2 up/down off. 2.7 mils would be a little excessive between two AI barrels for me, even with different cartridges. However, if the accuracy is there and you aren't destroying the brass is it worth chasing down for you?

Same/different muzzle devices/suppressors?

 

[morganlamprecht]

Here’s my AT from some point in the past when I had a bunch of barrels in rotation

+2 mils of elevation and +2.5 mils of windage @ 100 yd

Numbers are in mils, so you’d have to do the math to convert the differences to inches if you wanted…

was solid repeatable though…once I had them documented I’d throw different barrels on between matches, reset the zero on my turret, and go shoot.

I’d imagine the longer the barrels get the easier it would be see larger shifts, depending on the bore alignment/ chamber machining/etc

 

[CStroud]

Fast forward to around 16 minute mark

 

[Vivacious Stallion]

Seems a little more extreme than some, but if the zero is repeatable it kinda is what it is. You could contact AINA to get their opinion, but if it's shooting well idk if it's worth it.

Document it and know for the future. I don't blindly swap my barrels, even if I probably could, without a zero confirm shot.

 

[WVshooter]

The ASR submissions had to hold something like 1MOA at 100 yards. so if you see guys getting.4 or .3 with AI parts, thats probaby your expectation. If you were using 100% ai parts I personally would expect .3 to .4 and maybe worst case of .4- .6 (2moa).

The wrinkle here is you are using Proof prefits, so I don't know why you would expect that to work?

I mean the barrel's performance at that stage is Proof's problem not AI's problem.

Proof is only going to guarantee it headspaces/meets saami spaec, is safe to shoot, and is accurate (at some level). They aren't going to guarantee their barrel meets additional performance specs, unless that's clearly stated somewhere in writing.

Do you have a different expectation here?

I said in the post it was an AI .338 Lapua barrel and it's 2.7 mil low. The AI .308 and AI 300 Norma barrels were within .2 of each other. The Proof barrel is what it is.

 

[WVshooter]

I see a tenth or two in zero shift when I swap different cartridges back and forth in my AT-X. It generally takes 1-2 rounds to verify and adjust zero. This is with taking the same barrel off, and then reinstalling it again a few months later.

When I swap cartridges (6GT to 6CM etc..), I think I'm .5 left/right, and .2 up/down off. 2.7 mils would be a little excessive between two AI barrels for me, even with different cartridges. However, if the accuracy is there and you aren't destroying the brass is it worth chasing down for you?

Same/different muzzle devices/suppressors?

Yeah I talked to Frank and a couple other people I know with these rifles and most said they don't usually see more than a few tenths between any of their AI barrels. 2.7 seemed like a lot to me. Yes, same muzzle devices and suppressor on all barrels. TBAC Ultra 338.

 

[WVshooter]

Seems a little more extreme than some, but if the zero is repeatable it kinda is what it is. You could contact AINA to get their opinion, but if it's shooting well idk if it's worth it.

Document it and know for the future. I don't blindly swap my barrels, even if I probably could, without a zero confirm shot.

Yeah it's repeatable when removing and replacing the barrel. With no prior experience with this platform I was just hoping to get an idea whether this was normal or if it pointed to a possible problem since the swap between the AI .308 barrel and the AI 300 Norma were only about .2 different from one another. I already had to send the ZCO I bought in for service new out of the box so I'm just checking everything now.

 

[WVshooter]

Just to show what the results were, here's a photo of the shift between the 300 Norma and the .338 Lapua AI barrels.
The Norma was about .2 from the .308 zero.
The 6.5 was a Proof barrel so it's whatever.

 

[Roadrace33]

When i had my AXSR the 338 barrel was about 1-1.5mil off my 300 norma. But it was repeatable, so i never worried about it.

 

[WVshooter]

When i had my AXSR the 338 barrel was about 1-1.5mil off my 300 norma. But it was repeatable, so i never worried about it.

Thanks.

 

[TylerN]

Yeah I talked to Frank and a couple other people I know with these rifles and most said they don't usually see more than a few tenths between any of their AI barrels. 2.7 seemed like a lot to me. Yes, same muzzle devices and suppressor on all barrels. TBAC Ultra 338.

A few tenths has been my experience also. 2.7 mils is excessive, if it’s bothering you maybe see what AINA says.

 

[WVshooter]

A few tenths has been my experience also. 2.7 mils is excessive, if it’s bothering you maybe see what AINA says.

I contacted them and they said that was totally normal.
I asked if there was any standard it was expected to meet when switching barrels/calibers and they said there was not.
I found that surprising.

 

[TylerN]

I contacted them and they said that was totally normal.
I asked if there was any standard it was expected to meet when switching barrels/calibers and they said there was not.
I found that surprising.

Weird, I guess stick with the barrel or sell it if it's an issue.

 

[carbonbased]

Weird, I guess stick with the barrel or sell it if it's an issue.

I remember reading that outside of barrels aren’t perfectly straight, nor is the bore cut perfectly straight. I am not a machinist, so the following is rank conjecture.

Imagine a cylinder bent into a very slight banana shape. Now imagine the outside of the barrel is that shape. When they cut the bore, imagine that also is a banana shape.

Maybe if you get both “bananas” aligned just right, you get what the OP is getting? One theory, anyway.

Of course they could be wavy, and not banana-shaped.