Barrel Torque

[Niederlander]

Gentlemen,
      Does anyone here know how many degrees a barrel should be from top dead center when hand tight?  Specifically, for a '92 Winchester.

[Niederlander]

Anybody?

[Professor Marvel]

Greetings My Good Niederlander -

since no one else has spoken up, I went to my various resources and found the following wall of text:

Since switch-barrels can be tightened by hand, I cannot believe that a lot of torque is actuallly
required. On one forum, the discussion went from "hand tight" to "hand tight with loctite"
to

"Typically, 16 TPI threads are torqued to 80-100 ft/lbs.
Going to 24 TPI theoretically should up the number slightly,
but I would feel comfortable with 100 ft lbs."

the summary seems to be  "50-100 lb-ft is a decent range to be in."
with some measured advocating as low as 25 ft-lbs and others as high as (gasp) 250 ft-lbs.

over here (bear in mind this about Highwall actions.... ) :
http://www.assra.com/cgi-bin/yabb/YaBB.pl?num=1451319479/o

ssdave suggested:
but the typical advice is that you want a slight crush fit; many suggest .003". 
My experience from high walls is that they are about 20 to 30% of a flat off from lining up when they stop.
You torque them the rest of the way.  Doing the math:

16 tpi is approximately .0625" per revolution or .008" per flat.  so 2 thousands of crush fit is
about 1/4 of the flat.

when I barrel octagons, that is actually how I estimate how to face off the barrel to time the flats. 
I run the barrel in snug, but not torqued.  Estimate how much the flat is out of alignment. 
for each 1/8 of a flat it's out of alignment, I face off .001", leaving a couple of thousandths
for crush fit.  I try it and see if it's close, and re-estimate again if needed. 
When I get within 2 or 3 thousandths, I just torque it down to align and I'm done.

On a 12 tpi barrel, it's .010 per flat, so for each 10% of a flat you're off, you face off .001".

Simple gunsmithing for non-machinists 101.  If you're more particular or a "real" machinist,
do the math and measure exact.

and John Taylor, a professional gunsmith said:
If you want foot pounds then somewhere around 50 should do ( that might be to much on a small thread
like an 1890 Winchester). I have had some come in where the barrel could be unscrewed by hand.
I have seen factory barrels with shims between the barrel and action. The barrel should be tight
enough where it does not unscrew from the torque or the rifling when shooting ( left hand rifling).
There have been more than a few with loctite on the threads to keep them from turning.


aaaaaaand from www.HomeGunsmith.com Archive
---
Q:how much torque do you put on a barrel while installing on a receiver of a bolt action firearm ?
          and how would you measure the torque ?
A: I like at least 60, but not over 100ft-#.   I use a regular click style automotive torque wrench. 
   I welded a junk socket to my receiver wrench close to the opening to receive the wrench drive.
----

Finally from my old notes, some well over 10 years ago:

I have read now mostly in P S mag that smiths use 25-100ft/lbs
when tightening a barrel. One article I read said that using less
torque will keep the barrel from deforming.
Is there a happy medium? No barrel nuts are to be used.
If 25 ft/lbs is enough then that would be great, especially for
switching barrels but I have my doubts whether or not that's enough.
Somebody out there must have an experienced answer.


I swap barrels on my BR guns all the time. Years ago, I used to
use very little torque, maybe in the 10 ft-lb range, but one came
loose on me. For the past several years, I've been using in the
40-50 ft-lb range and haven't had any trouble.

I torque mine to 130 ft pounds. I arrived at this by welding a
big piece of hex onto my action wrench and using a torgue wrench.
What I do is bump the barrel firmly against the action shoulder,
then I draw a line with a pencil that connects the barrel and
action ring. I tighten the barrel untill there is 3/32 inch space
between the lines. I always use the line so I can see that the
barrel did indeed advance as I tightened it. On Farley, Remingtons,
and other actions with short 16 thread tangs, I believe it is
better to go a little tighter than looser.


Military and occasionally factory barrels are often very tight -
I estimate well over 200 ft pounds.

From personal experience I know that pistol barrels are often
turned in too tight. I have lapped (or cut Lewis chambers) in
many S&W barrels to relieve the constriction at the frame junction.
Bolt action rifles are a bit different as the constriction is over
the chamber and we are only talking about few ten thousanths worth
of distortion. I have seen this effect show up when cutting a few
thousanths out of a chamber on a barrel that has already been mounted
(after being orignally cut with the same reamer). The reamer will
produce more chips at the restricted area. This probably is not
critical, but I don't like the distortion. I usually shoot for
torques of 25-40 foot pounds using a high pressure lubricant/anti
seize compound, but wouldn't argue with someone who torqued to
slightly over 100 pounds (dry or using plain oil).

I believe the factory and military want to make sure that nothing
ever comes loose and they want to make sure the parts are "welded"
together. I prefer a good tight fit up, but without any forces that
produce permanent distortion or stresses. At this time, IMHO, less
torque is better as long as the barrel doesn't come loose.

For what it's worth! I use 80 to 100 lbs Torque (no locking plastic)

I believe I used around 80-90 ft lbs when I screwed on my 308 and
6.5-284 Lilja barrels on my Tikka m595 actions.

I'll by no means an expert. But I've been shooting a switch barrel
rifle since 1996. I got my second benchrest rifle w/ 2 extra barrels
last fall. Here's the way I do it.

I clamp the barrel in a good barrel vise with a paper wrap between the
barrel and vise. Usually a paper towel roll or a cut up old file folder.
After removing the present barrel, I wrap the threaded end and put it in
a barrel bag. (Home made, my wife used to like to sew.) I clean the
internal threads of the receiver with chemical naptha, or regular lighter
fluid. Make sure you clean the face of the receiver where the barrel
will lock up, and the mating area of the barrel. After checking the new
barrel for burrs and dirt on the threads, I apply a small amount of anti
sieze compound to the end few threads. (A spot about the size of a
green pea.) I use the FelPro / LocTite brand C5-A copper based formula.
After screwing the barrel back into the receiver up to just bump the stop.
Then I place the receiver wrench into the action and give it a healthy
smack with a large dead blow hammer. But not too hard. If I had action
wrenches that were the rear entry type that a torque wrench would fit.
I would probably have a more precise way to tighten the barrel.

I hope this helps.

+++++++++++++++++++++++++++
FWIW.... A new barrel with good threads and a true shoulder being put
on a custom action or trued-up Remington is torqued to about 70 ft.lb.
by me. I chose that number because it "felt about right" and I want
to be consistent. More or less will probably work fine.
I have seen a barrel (not one of mine) loosen up at a 1k match, the
shooter was not happy.

+++++++++++++++++++++++++++

At the 500 meter and 1000 yard benchrest matches, I've notice how quick
and easy these guys could change barrels and shoot great groups.
The action wrench slipped into where the bolt lugs went and had a
12" handle. I'm guessing about 50-65 ft lbs. When I asked my gunsmith
friend about this, he said that the barrels didb't need to be tighten
to where you start streching the threads and crushing the shoulder like
most factory guns. If you screw the barrel in until it seats against
the shoulder and tighten it down to about 50-65 ft lbs, that's all
you need. Seems to work for the Bench Rest Boys.

+++++++++++++++++++++++++++
K98 Barrels torque to 65-75 ft-lb. This equates to about 1/8 turn past
hand tight on a stainless barrel and about another 7 degrees past that
for chrome moly. Remember, the primary torquing occurs at the back face
of the barrel, not the exposed joint line where the barrel meets the
reciever ring. The secondary torque shoulder (exposed joint) provides
the tension, or thread stretch. Also remember, that after 100 rounds
of 180gr 30-06, a barrel torqued in at 65 pounds will now be at about
68 pounds. RH rifled barrels tighten up a little with each shot.
This tends to taper off around 77 ft-lbs. or so on good recievers
with a rockwell hardness of 38-42 to a depth of about .012-.015.
The main reason I bring all this up is this: Your bolt lugs should
be lapped to fit in between the space between the lug recess machined
into the reciever and the barrel's rear face. If you aren't torquing
the barrel in tight enough, what COULD happen is, with enough play
between the two, there could be a lug impact on firing, eventually
causing the lug to set back into the steel of the reciever. This could
lead to excessive headspace problems, especially if the bolt face
was lapped and not reheat treated to RC45-47. The other thing is
without the proper tension set between the primary and secondary
torque shoulders, you run the chance of "ovalling" the reciever
threads, a common problem in Mausers.

One of the slickest quick change set-ups I've seen yet was on a
mauser, though. The guy machined out a hollow bushing with 12 tpi
threads set for the depth of his Mauser, but it was blank cut inside.
It still had about 1/4" of secondary shoulder on it, and he torqued
it into the reciever. The exposed area of the bushing looked just
like the recoil lug on a 700 remington, or the barrel bushing of a
1911, just to give you a picture. His barrels were all cut similar
to a 10/22's. They just slipped in and tightened with 2 screws.
It was a solid 1 moa shooter with every barrel he had for it,
some got into the 1/2moa range.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

I have seen Mauser barrels that were on barely finger tight, and
others that needed three foot breaker bars. Most action wrenches
have long handles that apply more torque than you think. Cinching
up tight(I cant quote an actual torque value) is usually sufficient-
use some common sense, and be careful- I once saw an 09 Argentine
action twist up like a pretzel while it was being fitted.
A large ring Mauser has two fitting surfaces-- The face of the
receiver ring, and the internal collar or diaphragm. The barrel
shank length should match that dimension plus .002 inch. That
will allow an interference fit on the collar, and a transition
or clearance fit on the receiver ring. The .002 is an industry
standard to allow for the crush fit, and not leave a big gap
between the barrel shoulder and receiver ring.

I torque the 98's to 75 ft pounds and the rem to 60 the svage
with the barrel nut is is just snug.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

hope this helps
prof marvel

[Niederlander]

Very helpful!  Thank you!

[Professor Marvel]

My Dear Niederlander -

it is my pleasure to be of service! and, after posting that wall o' text, Irealized that you were not actually asking for
ft-lbs of torque, but

"how many degrees a barrel should be from top dead center when hand tight?"

wow. talk about   "reads well but poor comprehension" on my part .....

so.... 
The rifles I mainly build are muzzleloaders or BP carridge single shots.
mainly .

So I mainly deal with octagon barrels. And octagon breechplugs.
That means if the point of the octagon is at tdc, I have 1/16 of
a turn to get the flat "on top"



I personally find that 1/8 of a turn is too much, and I prefer 1/16 of a turn or less,
depending on how much "torque" is required.

I do hope I got my fractions correct...

As you can imagine I am in the 25-50 lbs crowd....

yhs
prof marvel

[Niederlander]

Good morning, Professor!  I think most barrels are over-torqued, especially revolver barrels.  I've developed a theory, on very limited experience, that one of many reasons for Smith & Wesson revolvers having a reputation for outstanding accuracy was the use of the cross pin to secure the barrel.  I've un-barreled several of them, and they were very lightly torqued.  In fact, a couple of them could be unscrewed by hand.  Thus, they didn't have the barrel squeeze at the frame that many revolvers today have.   Like I said, it's just a theory, and based on insufficient data, but I think it makes sense. 

Thanks again!

[Niederlander]

My Dear Niederlander -

it is my pleasure to be of service! and, after posting that wall o' text, Irealized that you were not actually asking for
ft-lbs of torque, but

"how many degrees a barrel should be from top dead center when hand tight?"

wow. talk about   "reads well but poor comprehension" on my part .....

so.... 
The rifles I mainly build are muzzleloaders or BP carridge single shots.
mainly .

So I mainly deal with octagon barrels. And octagon breechplugs.
That means if the point of the octagon is at tdc, I have 1/16 of
a turn to get the flat "on top"



I personally find that 1/8 of a turn is too much, and I prefer 1/16 of a turn or less,
depending on how much "torque" is required.

I do hope I got my fractions correct...

As you can imagine I am in the 25-50 lbs crowd....

yhs
prof marvel

So you're saying half a flat off tdc when hand tight would be correct?

[Professor Marvel]

So you're saying half a flat off tdc when hand tight would be correct?

Ah My Dear Niederlander -

I would not go so far as to say it's "correct"    
But it works well for me and I have had no blowups!  
or unscrewing, or any lack of accuracy ....

I settled upon half-a-flat since it did not seem to take a 200 lb man and a 6 foot wrench to achieve.
Ie: I could get there without destroying my bench, vice, tools or the gun or barrel...

It stays on so tight I need a wrench to get it off, so it is tighter than "hand-tight" and, I believe , in the 20-40 ish  ft-lb range.

Now you have tweaked my little grey cells, so I must get my automotive torque wrench modified to measure this ......

yhs
prof marvel