free floating barrel question

[Primer]

I have a Browning A bolt (ll) in 6.5 x 55 with a 20" barrel with a synthetic stock but when you look at the forend the space between barrel and forend is not equal either side but you can still slide a piece of A4 paper easily between the barrel and stock.
However this changes when I stick the moderator on it (Ase Utra Northstar, hefty piece of kit almost 700grams) and the barrel actually touches the stock on the left hand side and have been told this will effect the barrel harmonics and could be the reason for bad grouping of my Privi ammo which I don't get without the moderator fitted.

Now Fullbore rifles are new things to me and I don't quite get barrel harmonics but to the educated can the above cause problems with grouping and if so what should be my remedial action, should I file some of the stock away from where it currently touches to give some barrel clearance?

[meles meles]

No ooman, the rifle is beyond all salvation and so should be sent to the sett for disposal.

If you must keep it, then yes, remove just enough of the stock to ensure the barrel doesn't touch (assuming you can't re-seat the action such that it doesn't touch in the first place)

[Dangermouse]

It is usual to find a shift in point of impact when fitting a moderator so you may need two sets of settings for when you have it on and when it is off.

The moderator, if fitted correctly, should not detract from accuracy. Many feal that adding a moderator actually aids accuracy and grooups get smaller.

I would first look at making sure the moderator is fitted correctly. Then make sure the ammunition bullet weight is suitable for your barrel twist.
If both those are ok then perhaps you could then look at making sure the barrel is not touching the stock.

DM

[Primer]

No ooman, the rifle is beyond all salvation and so should be sent to the sett for disposal.

If you must keep it, then yes, remove just enough of the stock to ensure the barrel doesn't touch (assuming you can't re-seat the action such that it doesn't touch in the first place)

I did take the action off and I would have to remove the glass bedding to re do it to change anything on that side.

[meles meles]

ooh, don't do that !

Just, very gently, file away the stock so the barrel no longer touches anywhere when the hush kit is fitted....

[Primer]

It is usual to find a shift in point of impact when fitting a moderator so you may need two sets of settings for when you have it on and when it is off.

The moderator, if fitted correctly, should not detract from accuracy. Many feal that adding a moderator actually aids accuracy and grooups get smaller.

I would first look at making sure the moderator is fitted correctly. Then make sure the ammunition bullet weight is suitable for your barrel twist.
If both those are ok then perhaps you could then look at making sure the barrel is not touching the stock.

DM

Yeah the poi change by 3" down and 1" left with the mod fitted so that's fine to adjust but it's more the physical grouping, it's fine without the mod but with it on its poor with the Privi however I did try 6 reloads out (that need development) and they seemed to group fine (although about 4 inch lower) using the same 139gn bullet weight as the Privi but I need to develop the reloads and chrono them (now I have a chrono) as I think they were low on power as I didn't get very good obturation on the cases.

[safetyfirst]

You could shoot it upside down for a few groups, see if it works better.

[meles meles]

Aiming at kangaroos ?

[safetyfirst]

Or balloons.

[Dennisgrm]

Barrel/Stock clearance is recommended at a minimum of 1mm for use with a sound moderator. Especially with a factory 'plastic' stock. These stocks are very flexible and change characteristics in different temperatures.