FBecigneul
Member
What is the normal torque value when installing a .50 caliber BMG barrel to a McMillan Action?
.50 BMG Torque
- Thread starter FBecigneul
- Start date
jackie schmidt
New member
Francis, some years ago I helped the late Eric Klemitich install a 50 BMG Ackley Improved Barrel on a McMillan Action that had a 1.500 diameter thread. I think it was 12 tpi.
He had no way of holding it, or a large enough torque wrench. I chucked the barrel up in one of my large lathe’s 4 jaw chucks to hold it. He had a rear entry wrench with about a 1 inch hex on the end.
The torque he wanted was 150 ft pounds.
Hope this helps.
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Pete Wass
Well-known member
What about machinery's Handbook?
Might tell ya what the engineering value is and then one could consider perhaps reducing it a bit. Likely google could help as well.
My first real job was in an auto garage @ age 15. Whenever I'd ask the owner how tight he's say "about all that wrench will stand". Does that help any?
Pete
P.S. the chart I saw on Google sez 1316 to 1645 for a 1.50"-12
. If that's inch pounds it would be 109 to 137 ft/lbs. The chart shows some sizes with Ft Lbs and inch pounds. Likely the 109 would get it.. I used 50 Ft/lbs for years on my 30 barrels just to have a benchmark. Don't believe it stretched anything. I use 25 ft/lbs on .22 RF barrels.
Might tell ya what the engineering value is and then one could consider perhaps reducing it a bit. Likely google could help as well.
My first real job was in an auto garage @ age 15. Whenever I'd ask the owner how tight he's say "about all that wrench will stand". Does that help any?
Pete
P.S. the chart I saw on Google sez 1316 to 1645 for a 1.50"-12
. If that's inch pounds it would be 109 to 137 ft/lbs. The chart shows some sizes with Ft Lbs and inch pounds. Likely the 109 would get it.. I used 50 Ft/lbs for years on my 30 barrels just to have a benchmark. Don't believe it stretched anything. I use 25 ft/lbs on .22 RF barrels.
Last edited:
Might tell ya what the engineering value is and then one could consider perhaps reducing it a bit. Likely google could help as well.
My first real job was in an auto garage @ age 15. Whenever I'd ask the owner how tight he's say "about all that wrench will stand". Does that help any?
Pete
P.S. the chart I saw on Google sez 1316 to 1645 for a 1.50"-12
I was told years ago that in either the Model A or T service manuals the length of the wrench was specified for torque. Don't know never read one but I'm guessing they figured the average guy could get X torque with a certain size wrench.
Pete, an 8in wrench works just fine for rimfire barrels!
Keith
FBecigneul
Member
I forgot about the Machinist’s handbook. I tried here first. I also figured the 100 ft/lb area would be close.