Mich wrote:Morning guys,
Got a problem here I've never seen before. Due to head into town in the next week or so and can visit the smith but curious to see if anyone's come across it.
Have have an old - early 70's - Remington 700 that's been well used to say the least. The problem is this....
After having who knows how many hundred or thousands rounds through it I noticed the barrel had unscrewed a fraction of an inch from the action when brass started to look funny after being fired. Lucky I caught it when I did before it reached a more dangerous point.
The rifle hasn't been used for years, but has never had a problem. It was an old family rifle, I don't know 100% but I doubt the barrel has ever been removed.
Noticing the barrel I removed it, there is no unusual wear on the threads as far as I can see and for lack of a better option I can only assume at the moment it's being vibrated out over the course of a number of shots.
Any ideas?
Have seen the same thing once a long time ago. The cause then was a fracture running from the ejector port to the front of the action through the threads, that was invisible to the eye, but was detected using a Dye penetrant inspection method and confirmed with an Ultrasonic test. The problem was determined to be a combination of;
stress fractures originating from a contaminate in the steel used in the action, caused by the continued minute expansion and contraction of the barrel and action by the pressure generated when firing the cartridge. These fractures reduced the action's threads mechanical ability to lock the barrel threads in place.
the torquing of the barrel imparted by the projectile passing through the rifling.
This of course may not be the cause of your problem, but if you intend to kept using this rifle, and no obvious cause can be found, then it may pay to have your smith run a NDE (Nondestructive examination) on it for piece of mind.