Barrel torque question

For those that have some curiosity:

-Snug the barrel up by hand.
-Back it off about 1/16 of a turn.
-Using the action wrench, 'snap' it tight, but no further.
-Loosen the barrel and note how much torque it takes to break the barrel loose.

Now install the barrel this same way, fire 15-20 rounds and check how much force it takes to break the barrel loose.

Good shootin'. :) -Al
 
LISSEN to what The Al-man from Thee Frozen Tundra is saying...........And to alla' you'se who will actually TRY this experiment, ask yerself, WHY???

The Devil's in the WHY

al
 
RH twist, RH thread, barrel torque from firing transmitted from barrel through threaded joint...inertia of the rest of the rifle loads the joint... opposes, joint is tightened. Next question...;)
 
I'm new to this. Does Barrel tightness affect harmonics or vibrating?
Max
 
Well, yes, but more importantly for the joint to tighten it must unload at the shoulder-to-action abutment. In other words, the joint must open up and rotate and then set back down. In a new spot. It does this while under a high bending load so it never sets down exactly the same.

I got my first switch-barrel true-blue BR gun in the early 90's and it was sooo incredibly accurate that it simply reset my clock. With HAND TIGHTENED barrels.

I'd go out varminting or playing around on my range and screw barrels on and off with my hands, no tools. I got another good BR rifle used. Same thing...HID'jusly acc'rate...


I really thought my rifles were shooting! I talked about "going to a match and switching barrels between relays" etc.........It took me about five years of dinking around, shooting thousands of rounds, before I was good enough to see the difference. The simple fact is that BR rifles are marvelously engineered pieces of work, even with a loose barrel they shoot into one single hole.

BUT, set up right they make DOTS, little clean-edged holes in the paper. In fact, when all is well the hole just gets "smaller" with each shot fired....... It actually looks like it's shrinking,





but NOT with a loose barrel :)






al
 
So after all this discussion, statement of facts, theories, etc., I've come to the following conclusion. On properly machined and square surfaces like a barrel shoulder and receiver face, the difference between 120 ft/lbs. of torque applied with a torque wrench vs. a good hand tightening is negligible. I understand the concept of consistency and accuracy but I doubt the degree of material stretch will be significant from 60 ft/lbs. to 120 ft/lbs.
 
chino69 said:
So after all this discussion, statement of facts, theories, etc., I've come to the following conclusion. On properly machined and square surfaces like a barrel shoulder and receiver face, the difference between 120 ft/lbs. of torque applied with a torque wrench vs. a good hand tightening is negligible. I understand the concept of consistency and accuracy but I doubt the degree of material stretch will be significant from 60 ft/lbs. to 120 ft/lbs.
Click to expand...

Depends on the lube, Harold Vaughn warns of receiver distortion on the Rem700 while using lanolin as lubricant.

al
 
I should add that my earlier post about a 'snap tight' barrel fit isn't a recommendation on how much to tighten a barrel...it's simply an interesting experiment.

I actually do mine with a good amount of load & use a couple of witness marks.

Good shootin'. -Al
 
Al,
I understand the difference between wet & dry torque factors in a threaded joint. My point is the difference between a good manly 'umph', 60 ft/lbs. or 120 ft/lbs. on properly machined surfaces is negligible. I've used a torque wrench to replace match grade barrels fit and smithed by the best, as well as just snugged them up with a good manly snug and noticed no difference in performance or on paper.
 
Al Nyhus said:
For those that have some curiosity:

-Snug the barrel up by hand.
-Back it off about 1/16 of a turn.
-Using the action wrench, 'snap' it tight, but no further.
-Loosen the barrel and note how much torque it takes to break the barrel loose.

Now install the barrel this same way, fire 15-20 rounds and check how much force it takes to break the barrel loose.

Good shootin'. :) -Al
Click to expand...

As a followup to Al Nyhus post, this morning I changed some barrels. On two different Panda actions and with 4 different barrels, I tried just snapping the barrels hand tight. Then I'd make a pencil mark on the barrel and the action and then I'd put an action wrench with a torque handle on it and tighten to 100 ft/lb. On average the barrels would rotate an additional 0.060" of circumference.
 
IMO it's important to note that "shooting tight" isn't a lubrication function. Barrels don't tighten from rotational torque but from pressure expansion. A barrel will tighten up even with minimum lubrication if the tenon isn't stretched far enough.

al
 
JerrySharrett said:
As a followup to Al Nyhus post, this morning I changed some barrels. On two different Panda actions and with 4 different barrels, I tried just snapping the barrels hand tight. Then I'd make a pencil mark on the barrel and the action and then I'd put an action wrench with a torque handle on it and tighten to 100 ft/lb. On average the barrels would rotate an additional 0.060" of circumference.
Click to expand...

Jerry, that .060 is about where I end up.

Good shootin'. -Al
 
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