Barnard switch barrel torque.

[srj]

Hi guys.
I've just got a second barrel to use with my Barnard, & was
wondering whether I should use a tension wrench to torque to a specific
tension & be repeatable, or just tension by hand & go on feel.

Any advice would be appreciated. Thanks.

[johnk]

I torque my barrels to 80ft/lb. Works for me, so I haven't gone elsewhere.

[srj]

Thanks for the info John, I will give that a try !

[bsouthernau]

I torque my barrels to 80ft/lb. Works for me, so I haven't gone elsewhere.

Me too. Others just do it by feel with good results. I suspect it doesn't matter much because they tighten up as you shoot them.

[jasmay]

I torque my barrels to 80ft/lb. Works for me, so I haven't gone elsewhere.

Me too. Others just do it by feel with good results. I suspect it doesn't matter much because they tighten up as you shoot them.

Ehh? do they? Right twist barrel, isn't the torque undoing it?

[mike H]

I torque my barrels to 80ft/lb. Works for me, so I haven't gone elsewhere.

Me too. Others just do it by feel with good results. I suspect it doesn't matter much because they tighten up as you shoot them.

Ehh? do they? Right twist barrel, isn't the torque undoing it?

The only barrel I have seen come really loose was a .303 on a number 4 action,a left hand twist.

[bsouthernau]

Ehh? do they? Right twist barrel, isn't the torque undoing it?

Oops... Am I wrong again?

[KHGS]

Ehh? do they? Right twist barrel, isn't the torque undoing it?

Oops... Am I wrong again?

No, you are not wrong. In theory you are, but in practise you are not! Another example of things are not always as they seem or should be.
Keith H.

[DaveMc]

No - not wrong in theory or practice.

For every action there is an equal and opposite reaction. The barrel spinning the bullet to the right will result in the bullet spinning barrel to the left (looking from action - don't advise looking from muzzle in this exercise ) and tightening it.

[RAVEN]

SRJ
I just go by feel if the barrel work is done properly nip up with a short bar on a socket
BTW I don't have a tension wrench and using one to tighten to a consistent torque would be good practise.

I can’t advise you what that would be but JohnK is very experienced and maybe a good place to start
Would be interesting to hear what Keith’s view is on this.

The main thing is don’t over tighten as you will just stress the treads and that’s probably not the best thing to do.

RB

[KHGS]

SRJ
I just go by feel if the barrel work is done properly nip up with a short bar on a socket
BTW I don't have a tension wrench and using one to tighten to a consistent torque would be good practise.

I can’t advise you what that would be but JohnK is very experienced and maybe a good place to start
Would be interesting to hear what Keith’s view is on this.

The main thing is don’t over tighten as you will just stress the treads and that’s probably not the best thing to do.

RB

I do not always use a torque wrench, but I suggest that 80 to 100 ft lbs is about right for a non switch barrel set up. More like 60 ft lbs for switch barrels. Most times it will be by feel. One comment I would make is that over years my observation is that a lot of barrel fitters tighten target barrels more than necessary when fitting them.
Rear entry action wrenches & the aluminium v-block barrel vices used by switch barrel users usually self limit the amount of torque that can be applied to a barrel. If I am fitting a barrel & am not informed by the owner that it is to be switched, they will have difficulty removing the barrel with that equipment. I will say (tongue in cheek) that there are those who should never switch barrels!!! Therein are a whole bunch of other stories that I will not go into only to say you would be amazed at what I have seen in 40 years of working in the firearm industry .
Keith H.

[AlanF]

Keith,

I have regretted switching barrels from time to time .

But your torque figures are pretty much what I use. I was doing 80 ft-lb for years but have reduced that to 60 recently and its easier to manage with no problems experienced.

Alan

[williada]

For what its worth, Peter Hallet one of our most revered shooters and armouror told me 38 years ago to use 120 ft pound and he did relate a story of a loose barrel to me he thought was very amusing. In recent times Harold Vaughan who wrote Rifle Accuracy Facts used the same figure. So I am firmly in Keith’s camp. I know Jim Boatright might go as low as 35 ft pounds with switch barrels but he uses short barrels that don’t give the same flogging say a 32 inch barrel does and makes an argument for not damaging threads and is opposed to crush. I am not happy with that due to joint expansion or contraction and odd shots. Yes head bolts on vehicles are commonly torque to 80 ft pound and there are lots of them for good reason.

Anyone that has chambered and fitted many barrels will tell you the act of drawing up the action on new threads wont reference in the same place with the same torque on the wrench if you undo the action a few times. You must do that to wear the threads a bit before you finally set headspace. Once set you forget it. An immortal American gunsmith McFarlane in his reference advocates polishing the threads for that reason and to reduce vibration. It’s not too hard to know why when it comes to frequency tune.

The advent of Spirolock thread design where the peaks of the barrel rather than the slopes of the threads centralise things are faced with a real wear problem with switch barrels. In my view a very a well cut thread where the crests and trough do not touch and centralised by the 60 degree thread where the shoulder and action faces are held flush with a .002” crush, the barrel will give consistent vibration pressure.

Anyone understanding the importance of thread crush stability realises the importance of bumping shoulders back .001”-.002” because it stabilizes bolt thrust which is a major source of vibration. David.