Removing/reinstalling barrelled action changes tune ?

[Martin52]

For ease of cleaning I remove the barrelled action (Barnard P, 30 inch Bartlein) from its FTR timber stock, this also allows me to store in the safe with the muzzle facing down. I'll then just re-instal before the next match.

After reading a few tuning threads I wonder whether this removal/reinstallation will affect the tune and whether its best to just leave the barrelled action installed ? Sometimes it's hard to say whether a good/poor match result is due to shooter error, poor wind reading, or possibly arises from disturbing the tune by removal and re-installation of the barrelled action.

The action sits in a Barnard metal bedding block.

 

[Bob3700]

At the next match does ur zero need adjusting?

 

[Martin52]

At the next match does ur zero need adjusting?

Elevation zero can be out by up to 1MoA. Wind zero is usually Ok.
Thinking the barrel harmonics might change when reinstalling the barrelled action.

 

[jpjulian]

If you aren't already doing so, use a torque wrench for the action screws so they are installed the same each time. That should help with a consistent zero.

 

[Keith Glasscock]

Years and years of pulling a Barnard out of the stock and putting it back in for various reasons never resulted in a need to change the load. In my opinion, tune does not change.

If the bedding is a problem, you will see zero changes and what appears to be tune changes simply from the action not nestling down the same each time.

 

[Clancy]

I’ve got a couple of rifles that I just feel better cleaning in a vise. One has nice wood and the other has a comb high enough I can’t get a bore guide with solvent port in it. Zero doesn’t change after reassembly, and yours shouldn’t either if you have a properly bedded rifle.

Here’s a tip:

After cleaning, flip the barreled action over and drop the stock on from the top side. Have 2 fix it sticks handy. One about half of your desired torque and the other full value. I use a 25 and a 45. (It’s crazy to me to run 65 on a properly bedded rifle.) ANYWAY, tighten the front screw to half, then the rear screw to half, then go back to the front screw with the full torque stick, followed by the rear screw at full torque.

If you do that and your zero changes, pretty much a guarantee that you’ve got some stress. I’d consider bedding instead of the block if it were me. It’s simple enough to check it with a dial indicator.

 

[Martin52]

If you aren't already doing so, use a torque wrench for the action screws so they are installed the same each time. That should help with a consistent zero.

Yes, I have been using a Gehman 705 torque wrench to 7Nm or ~ 65 inch pounds. Could be excessive. Will back off a little.

 

[Martin52]

Years and years of pulling a Barnard out of the stock and putting it back in for various reasons never resulted in a need to change the load. In my opinion, tune does not change.

If the bedding is a problem, you will see zero changes and what appears to be tune changes simply from the action not nestling down the same each time.

Thanks, on that basis I'll have to get the bedding block checked. It was installed by the timber stockmaker using handtools, no CNC.

Are you using the Barnard bedding block or an alternative bedding solution ?

 

[Martin52]

I’ve got a couple of rifles that I just feel better cleaning in a vise. One has nice wood and the other has a comb high enough I can’t get a bore guide with solvent port in it. Zero doesn’t change after reassembly, and yours shouldn’t either if you have a properly bedded rifle.

Here’s a tip:

After cleaning, flip the barreled action over and drop the stock on from the top side. Have 2 fix it sticks handy. One about half of your desired torque and the other full value. I use a 25 and a 45. (It’s crazy to me to run 65 on a properly bedded rifle.) ANYWAY, tighten the front screw to half, then the rear screw to half, then go back to the front screw with the full torque stick, followed by the rear screw at full torque.

If you do that and your zero changes, pretty much a guarantee that you’ve got some stress. I’d consider bedding instead of the block if it were me. It’s simple enough to check it with a dial indicator.

I usually flip my barrelled action upside down on a cleaning cradle then drop the timber stock down onto it. The action bolts are then tightened alternately until tight, but at ~65 it may be too much. As mentioned in my reply to Keith, I'm going to check the bedding, and I'll also look into a potential alternative.