AI Switch Barrel Repeatability

[Mike4837]

Accuracy International users won't be surprised by this, but I know the question comes up from time to time about the repeatability and accuracy of the AI when you switch barrels so I thought I'd share this and maybe others will chime in too.

I have a left-handed AI AT. I have a 6XC barrel, 6.5 Creedmoor barrel, and two .308 barrels for it. I've got a class next weekend so I wanted to get everything setup and ready for it. I put the 6.5CM barrel back on it. The turrets on my scope were zero'd to the 6.5CM, but I had been doing some load development with one of the .308's and had moved the turrets off zero, but not reset them. So I put the 6.5 barrel on, changed my turrets back to zeros and went to shoot. The buddy I was shooting with that day wanted to start at 1065 yards and work back. We setup an 18x24" piece of steel and drove back. I ranged it with a Terrapin X to confirm distance, laid down and shot. I'm a terrible wind caller and it took me a couple rounds to get the wind dialed in, but the picture included is the target.

Yes. That's ditch weed behind the target. Anyway, the 3 shots below the line were 9.0 mils and the one above the line is 9.1 mils. So what's my point? My point is that I swapped barrels and trusted the system to remain accurate and repeat and went straight to 1k yards. AI's system is excellent. I've also done zero checks where I shoot a 10 round group, one shot at a time and remove the barrel between each shot. If you're on the fence about an AI. Don't be. They're outstanding rifles.

As an aside, I used my Zero Compromise Optic ZC420 for this. It's quickly becoming my favorite scope ever.

 

[ShtrRdy]

My experience when re-mounting a barrel is it takes 1 or 2 rounds to settle the barrel in.

Would you mind explaining your process of installing a barrel in a AT? Do you hold the chassis vertical? Do you apply torque to the barrel? How many in-lb are you applying to the clamp bolt?

Thanks -- Todd

 

[Mike4837]

My experience when re-mounting a barrel is it takes 1 or 2 rounds to settle the barrel in.

Would you mind explaining your process of installing a barrel in a AT? Do you hold the chassis vertical? Do you apply torque to the barrel? How many in-lb are you applying to the clamp bolt?

Thanks -- Todd

I'm too lazy to hold the chassis vertical. I just use the bipod to support the rifle,. I hand tighten the barrel and then use a 49in lbs torque limiter as specified in the manual for the clamping bolt.

 

[Bertoli888]

Nice shooting

 

[desertHK]

Accuracy International users won't be surprised by this, but I know the question comes up from time to time about the repeatability and accuracy of the AI when you switch barrels so I thought I'd share this and maybe others will chime in too.

I have a left-handed AI AT. I have a 6XC barrel, 6.5 Creedmoor barrel, and two .308 barrels for it. I've got a class next weekend so I wanted to get everything setup and ready for it. I put the 6.5CM barrel back on it. The turrets on my scope were zero'd to the 6.5CM, but I had been doing some load development with one of the .308's and had moved the turrets off zero, but not reset them. So I put the 6.5 barrel on, changed my turrets back to zeros and went to shoot. The buddy I was shooting with that day wanted to start at 1065 yards and work back. We setup an 18x24" piece of steel and drove back. I ranged it with a Terrapin X to confirm distance, laid down and shot. I'm a terrible wind caller and it took me a couple rounds to get the wind dialed in, but the picture included is the target.

View attachment 7100016

Yes. That's ditch weed behind the target. Anyway, the 3 shots below the line were 9.0 mils and the one above the line is 9.1 mils. So what's my point? My point is that I swapped barrels and trusted the system to remain accurate and repeat and went straight to 1k yards. AI's system is excellent. I've also done zero checks where I shoot a 10 round group, one shot at a time and remove the barrel between each shot. If you're on the fence about an AI. Don't be. They're outstanding rifles.

As an aside, I used my Zero Compromise Optic ZC420 for this. It's quickly becoming my favorite scope ever.

I have the old AI PSR system for 308, 300 WM and 338 LM. Recently, I acquired a barrel for the 6.5 creedmoor. When I first got the rifle, there was a moderate amount of shifting when I change from one a barrel to another. As I put more rounds down range, I noticed that the shifting went away and the POI was consistently at the pre-determined off set zero for the particular caliber.

 

[Mike4837]

I have the old AI PSR system for 308, 300 WM and 338 LM. Recently, I acquired a barrel for the 6.5 creedmoor. When I first got the rifle, there was a moderate amount of shifting when I change from one a barrel to another. As I put more rounds down range, I noticed that the shifting went away and the POI was consistently at the pre-determined off set zero for the particular caliber.

That's interesting to me. I have noticed the occasional 1 to 2 round shift that @ShtrRdy mentioned, but in my experience it has been after cleaning a barrel. Do you have any hypothesis what the change was for you when you stopped noticing the shift?

 

[desertHK]

That's interesting to me. I have noticed the occasional 1 to 2 round shift that @ShtrRdy mentioned, but in my experience it has been after cleaning a barrel. Do you have any hypothesis what the change was for you when you stopped noticing the shift?

Not sure why to be honest. May be I did not torque the side screw in tightly consistent enough? Barrell settling down? Not sure why but happy that it didn't.