What Torque for a Barrel to Action?

[CjC73]

Looking for help....

I'm about to install a 223 Rem barrel that was originally threaded for a Curtis Valor QC action onto a Curtis Scout action. I was told to use the 0.300" recoil lug and that is all.

Looking at the tenon prints for the QC action with a 0.250" recoil lug and the Scout action with a 0.300" recoil lug, the difference is only 0.005". That is in the tolerance of a SAAMI 223Rem, correct? So I can just torque it check with gages? What torque is the correct torque though? Suppose it might not be one specific torque but where would i start?

I also posted an ad looking to borrow gages for the 223 Rem and a Curtis action wrench to borrow, so if you have these, I'd be willing to pay for your shipping so I could use them for this install.


Thanks

 

[jaclthr]

Hello CJ ,

I normally use 80 ft lbs. when I torque actions to barrels . I don't know if it was a type o or not but you math is wrong , 0.250" from 0.300" is 0.050" not 0.005" , just in case.

jaclthr

 

[ARlife4me]

Note he should be or possibly is stating 80 ftlbs not feet per second (fps).

 

[VinceMule]

CjC73, you have a mistake in your math, there is .050 difference. You will need a .300 recoil lug.

 

[CjC73]

yes, I can do simple math. thanks

As I said in my post, looking at the tenon prints and using the two different lugs, the difference is only 0.005". I'll explain for they algebra wizards.

QC tenon print is 0.725" from lug face to end to chamber.
Scout tenon print is 0.680" from lug face to chamber.

QC barrel tenon with a 0.300" lug leaves 0.425" (for my math wizards: 0.725-.300 = 0.425)
Scout barrel tenon with a 0.250" lug leaves 0.430" (again, 0.680-0.250 = 0.430)

So..... 0.430" -0.425" = (drum roll please) 0.005"!



So, I'll use the 0.300" lug and torque it to approx 80 ftlbs.

 

[ARlife4me]

yes, I can do simple math. thanks

As I said in my post, looking at the tenon prints and using the two different lugs, the difference is only 0.005". I'll explain for they algebra wizards.

QC tenon print is 0.725" from lug face to end to chamber.
Scout tenon print is 0.680" from lug face to chamber.

QC barrel tenon with a 0.300" lug leaves 0.425" (for my math wizards: 0.725-.300 = 0.425)
Scout barrel tenon with a 0.250" lug leaves 0.430" (again, 0.680-0.250 = 0.430)

So..... 0.430" -0.425" = (drum roll please) 0.005"!



So, I'll use the 0.300" lug and torque it to approx 80 ftlbs.

When info is left out then it's difficult too know what's going on in your head? From what the 1st post had I would have too agree with the .050" difference.

 

[CjC73]

what info was left out? it is in the first post. "Looking at the tenon prints for the QC action with a 0.250" recoil lug and the Scout action with a 0.300" recoil lug, the difference is only 0.005"

I agree, I didn't spoon feed you all the information. I'm sorry

 

[VinceMule]

You had already worked through the solution, you just need action wrench?

Have you determined if a Rem 700, Ruger 77, Tikka, action wrench have bolt lug thickness that may work for your application, and a call to the action maker is in order to determine this. I use modified Davidson Action rear entry action wrenches for all the above. You may feel more confortable with the outside action wrench that goes around the dia of the action, I have both and have never had problems with the Davidson type.

Borden and Stolle are the two actions that I trust to chamber/thread/headspace off of an Action print only.

If you had two Curtis actions of the same model, piece-to-piece variance could be a little, not to mention how the different barrels were heaspaced with +/- as there is around .003-.004 spread between Go and NO go gauges, tolerances stack up, I hope you get lucky!

After you get the barrel screwed on tight on the action(there is up to .002 stretch in the elastic limit of the thread):

Using .020 thin solder, cut a small piece and place on the bolt nose, close the bolt. Then carefully remove the small piece of solder from the bolt nose, and Measure with a micrometer that measures to the .0001. If the small piece of solder sticks to the back of the barrel, remove it, and start the process over. You need to know what is the acceptable bolt nose to barrel tenon clearance.

Then check the headspace. If you do not have headspace gauges, you can check with a new case. Checking with a new case is somewhat problematic due to headspace variance within a lot# of brass, determine the spread in headspace with an oversize ogive gauge that will touch the shoulder. Check headspace with a short headspace length and a long headspace length with black soot on the shoulder and neck. When you extract the case, then check to see where on the shoulder the soot mark has been rubbed. If the new cases of various lengths shows no contact on the shoulder, then try a new case fired in another rilfe(not AR type), and see if that case has any contact on the shoulder after measuring the headspace length of that case and perhaps the web dia to the .0001.

Best wishes, and I will say that there is a very good chance of your being successful in your endeavor!

Curtis Custom - Actions

Having a machinist thin the "ears" on a davidson action wrench is a no brainer!