It'll be a couple weeks before I have the time to really devote a day to test the repeatability of the BarLoc so I figured I'd go ahead and post my initial impressions and results. I have tested the BarLoc out on three range trips, between 6.5CM and 5.56.
I am using a Vortex AMG with the micro adjustment zero turrets. I zero the 6.5CM barrel with the micro adjustments and then just used the turrets to adjust for the 5.56 offset.
Day 1 (Hand tight)
I simply tightened the barrels down hand-tight. While doing this I noticed that the barrels started to get "hand tight" around the 10' Clock mark. 10-10:30 provided the best bolt feel, but the barrels could be tightened down even further to 11-11:30.
With this range from 10-11:30 in barrel tightness (~45deg) the zero shifted considerably every time a barrel was changed. In the range of anywhere from 0.5-1.5mils on elevation and windage. I did not take good notes during this time as there was a lot of swapping and adjustments being made.
Day 2 (witness marks)
On the second day I used witness marks, made with paint pen, on both sides on the barrel, referencing the chassis. I could not reference the action because of the BarLoc. I could not reference the BarLoc because it's orientation shifts ever so slightly every time.
6.5CM Zero 8.8E, 9.1W
5.56 Adjustment +1E, -0.4W
I switched back and forth a couple times and the zero on the 6.5CM was within +/- 0.5Mils. The 5.56 was within +/- 0.2Mils.
Day 3 (witness marks, bolt feel, level break)
On the third day I still used the witness marks but adjusted (within the thickness of the witness marks) based on bolt feel. I also used a bubble level to make sure the breaks were level as another point of reference for repeatability.
6.5CM Zero 8.4E, 9.1W
5.56 Adjustment +1.1E, -0.2
I only switched from 6.5CM to 5.56 and back to 6.5CM as I wanted to get good dope out to 1k on the 6.5CM before the rain came. 6.5CM was still within +/-0.5Mils. The 5.56 was still within +/- 0.2Mils but I added a muzzle break and suspect this had something to do with it.
Conclusion
The system works well and is much easier to change barrels as opposed to a barrel nut or conventional action wrench. Some of this error could easily be attributed to me as a shooter. The 5.56 barrel does seem less susceptible to shifts in zero. The only additional procedure I may try is using Go/No-Go gauges when swapping barrels. I will also try leveling the BarLoc after every swap, although I think this will be difficult due to the notch on the bolt end of the BarLoc. Besides that I would suggest using witness marks and re-zeroing the larger calibers after every barrel swap.
I am using a Vortex AMG with the micro adjustment zero turrets. I zero the 6.5CM barrel with the micro adjustments and then just used the turrets to adjust for the 5.56 offset.
Day 1 (Hand tight)
I simply tightened the barrels down hand-tight. While doing this I noticed that the barrels started to get "hand tight" around the 10' Clock mark. 10-10:30 provided the best bolt feel, but the barrels could be tightened down even further to 11-11:30.
With this range from 10-11:30 in barrel tightness (~45deg) the zero shifted considerably every time a barrel was changed. In the range of anywhere from 0.5-1.5mils on elevation and windage. I did not take good notes during this time as there was a lot of swapping and adjustments being made.
Day 2 (witness marks)
On the second day I used witness marks, made with paint pen, on both sides on the barrel, referencing the chassis. I could not reference the action because of the BarLoc. I could not reference the BarLoc because it's orientation shifts ever so slightly every time.
6.5CM Zero 8.8E, 9.1W
5.56 Adjustment +1E, -0.4W
I switched back and forth a couple times and the zero on the 6.5CM was within +/- 0.5Mils. The 5.56 was within +/- 0.2Mils.
Day 3 (witness marks, bolt feel, level break)
On the third day I still used the witness marks but adjusted (within the thickness of the witness marks) based on bolt feel. I also used a bubble level to make sure the breaks were level as another point of reference for repeatability.
6.5CM Zero 8.4E, 9.1W
5.56 Adjustment +1.1E, -0.2
I only switched from 6.5CM to 5.56 and back to 6.5CM as I wanted to get good dope out to 1k on the 6.5CM before the rain came. 6.5CM was still within +/-0.5Mils. The 5.56 was still within +/- 0.2Mils but I added a muzzle break and suspect this had something to do with it.
Conclusion
The system works well and is much easier to change barrels as opposed to a barrel nut or conventional action wrench. Some of this error could easily be attributed to me as a shooter. The 5.56 barrel does seem less susceptible to shifts in zero. The only additional procedure I may try is using Go/No-Go gauges when swapping barrels. I will also try leveling the BarLoc after every swap, although I think this will be difficult due to the notch on the bolt end of the BarLoc. Besides that I would suggest using witness marks and re-zeroing the larger calibers after every barrel swap.
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