Loose Barrel

[cat64]

Hey guys,

Just seeking some words of wisdom as to what might have happened and what will I do next.... I have a target action with a CBI 6.5X47 Lapua barrel which I put together myself. It has an improved barrel nut and recoil lug. I torqued the barrel in the action at 44 lbs two months ago adding some anti seize. Tonight as I proceeded to check the rifle before a range trip, something felt loose. Then I discovered the barrel was loose such that I can unscrew it with my hand. Hmmmm, why is this happening and what should I do differently tomorrow as I put the platform together? The stock is a B&C Medalist (free floated).

 

[Ggmac]

If it was mine , I would disassemble , clean , inspect . Paying attention and measure Id and Od threads and tenon . If nothing is found , reassemble with anti sieze if stainless / stainless . This time after torquing make an obvious witness mark that is visible , on the nut and barrel .
Time for COFFEE , good luck

 

[Larryh128]

Unfortuneately that can happen with pre-threaded barrels. Sounds to me like the barrel threads are slightly undersize to the action threads. While it is not a good fix, you can run a couple wraps of teflon tape to take up the slop.

 

[Toolbreaker]

Just to add to what has been said (and while you have it apart), check the lug, action face and nut for any burrs/trash that may prevent the assembly from seating flush when tightened. An India or Arkansas stone will tell you in an instant if this is the case.

 

[gotcha]

Just to add to what has been said (and while you have it apart), check the lug, action face and nut for any burrs/trash that may prevent the assembly from seating flush when tightened. An India or Arkansas stone will tell you in an instant if this is the case.

If all else fails, you may need to true the face of your action. The improved nut & lug, IMHO, require this be done to assure precision fit.......

 

[Rustystud]

Clean it up and properly measure it with the three wire method. Measure the action threads with a thread gauge. If with in spec. Reassemble without the anti seize, use liberal application of high temperature bearing grease. Head space on go gauge. Torque to 65ft lbs. Re check with No-Go Gauge. The grease will allow the threads to seat tighter. The Machinist Handbook recommends grease on all threads to be torqued to a specified weight. Grease does not look like copper or aluminum when applied. I provides both lubricity and anti corrosion properties.

If you don't have the skills and tools to do the following, take it to someone who can.
Nat Lambeth

 

[carlsbad]

I would add to inspect with magnification for any burr, imperfection, or roughness that might be preventing the threads from properly pulling the barrel into it's proper seated location.

I would then tighten and loosen the nut several times with good lubrication to improve the fit between the male and female threads. I refer to this as "embeddment".

I agree with the recommendation to increase the torque.

I don't like using teflon tape. I would worry that it might extrude with heat.

Put a scribe or magic market line on the nut and check it frequently at the range. This is a safety issue. A loose nut should show up first in accuracy but a loose joint could blow apart too. Be careful out there.

--Jerry