Gallery of Dramas. Broken Enfield Parts!

[jmoore]

That is why I thought it important to mention. However, due to years of poor storage beforehand, they were of even less value "as is"! Didn't know we were going to get as involved in the "nitty-gritty" at first. In actual fact, IF I had some way of doing super macro shots, much detail is still usable. Lemme cipher on it a while...

I think there's another cocking piece untouched somewhere, as well. Off to edit and clean up some previous posts to make references easier. (Destroying their historical value! The posts, that is...)

ETA1 More distressed parts coming! Anybody else?

ETA2 The distressed safeties are looking interesting. There's a Savage in the collection that has some safety wear dramas...

ETA3 For ease of reference just call out the post number for those posts that don't get photo numbers. So far, they all contain just one photo each.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[RJW NZ]

A little wreckage, a 1918 BSA. The sight middle screw was once upon a time, stripped then the head cut off and put back in the hole, the whole sight then being braised to the wrist. When I opened it up my 'shootable' enfield had major yikes! issues. Time to break out the West epoxy.

[jmoore]

Fortunately for y'all, RJW NZ made some good photos of a distressed SMLE Mk.III* fore stock (Post #20), otherwise...

There's no escape, however, as warned- here's a little more:


No.4 Savage rear swivel assembly that's come adrift. Not a major crisis, but probably annoying if it occurred in the field.


Another cocking piece- uncleaned this time, but not as filthy as the others. Failed in "stages" on TWO roughly parallel planes which were joined by the fracture in the center.

Will try for some more shots of this one if anyone's interested.

Have yet to root through the old barrel pile!

[breakeyp]

Fortunately for y'all, RJW NZ made some good photos of a distressed SMLE Mk.III* fore stock (Post #20), otherwise...

There's no escape, however, as warned- here's a little more:

http://i20.photobucket.com/albums/b2...restuff012.jpg
No.4 Savage rear swivel assembly that's come adrift. Not a major crisis, but probably annoying if it occurred in the field.



http://i20.photobucket.com/albums/b2...restuff014.jpg
Another cocking piece- uncleaned this time, but not as filthy as the others. Failed in "stages" on TWO roughly parallel planes which were joined by the fracture in the center.

Will try for some more shots of this one if anyone's interested.

Have yet to root through the old barrel pile!

Playing the Ford Motor Co. game, an FMEA (Failure Mode Effect and Analysis) of the poorly staked swivel could be due to:

For the swivel, material incorrect, material diameter not correct, upset incorrect due to tool wear, out of print or movement of anvil during staking operation.
For swivel base, swivel hole oversize, incorrect material allows hole to deform during staking operation and not grip the upset.
Staking operation: Insufficient pressure during staking, anvil/fixture movement during staking opertion. Slippage during insertion of wire staked area in the base (If that is how they did it).

Without knowing the process, one can speculate even more issues/concerns.

Comment for what they are worth. This speculation would be followed up by a visit to the manufacturer and deep analysis of his assembly process and controls to insure it does not happen again. Apparently Savage didn't get the message or their sub supplier.

[Mk VII]

Seen several of those staked swivels fail. One can get them welded up again, and "good for another sixty years".

[Claven2]

I love this thread, though I can't for the life of me understand those cocking pieces being broken so frequently in that spot. Frankly, apart from resisting spring pressure at the sear, it's not an overly stressed part. The fracture looks, to me, like an impulse fracture and not a ductile one from plastic deformation. This suggests over-hardening in the metal structure, possibly martensitic steel throughout, while Pearlite with a hard surface or Bainite throughout would have been a much better heat treatment goal for these bits. But then, it's possible that the manufacture was bunged up to begin with and the wrong hardness was the result.

The bolt heads aren't failing in tension as the bolt design would not generate enough force on extraction. I'm thinking it's a combination of too much bolt head slop in battery coupled with uneven wear on the locking lugs causing uneven shear stress on firing. Again, the fractures are not from plastic deformation but look immediate.

One failure I've seen fairly often (no pics though) is the receiver wearing out such that the bolt has too much vertical travel causing iffy sear engagement. You see it on receivers with a lot of miles on them, and more often than not a few rebuilds, some of which were probably done in India where one wonders if the armory had gauges.

I have also seen the receiver bridge inserts fall out on some No.4's, presumably from some shock to the receiver.

[breakeyp]

Consider the relationship of the cocking piece and sear engagement. Smartly slamming the bolt home generates a high stress on the nose of the cocking piece as it hits the point of the sear. I suspect that a condition called impact loading might enter here. It has been years since I fiddled with this stuff, but as I remember there were formulas that tried to account for the addional loads encountered when things were slammed together. High loads and the offset difference between the area (notch effect) of the cocking piece body and the extended nose of the cocking piece and the point of contact with the sear nose creats a moment (force moving on a radius of action) that can put quite a tearing force on the cocking piece. If there is a weakness, sharp corner, material hollow/inclusions--- the part breaks. Like many engineering formlas, you have to make real world tests to get the constants you need to make the formula work for that particular case. In school you were given frictional constants for problems but in the real world you had to test to find them and then proceed with the caluclations that may work or may not. Thank God for safety factors where you design for parts to accept 4 or 5 times the expected loads.

I hope this hasn't bored you too much. It is hard to do this stuff without paper and pencill.

[jmoore]

I love this thread, though I can't for the life of me understand those cocking pieces being broken so frequently in that spot.

Something that came up in one of Spinecracker's threads may help explain part of the reason beyond those already listed: Inspection stamp impressions located in the stressed area! The localized deformation is a perfect nucleus for "fatigue failure" in an area that wouldn't otherwise be expected to see large cyclical loads. Little things can make a huge difference!

Link to Spinecracker's thread below, ref. Posts #53 through #58- possibly more.:

https://www.milsurps.com/showthread.php?t=21764&page=6
"New '41 Long Branch..."


Railroad bogeys (wheels, specifically) were one of the first well investigated items where tiny inspection stamps in the web led to catastrophic failures (and some derailments!) long into their service lives. I know that Glock Inc. moved the location of their slide proof marks away from the ejection port for the same reason. (I may have even been the one that first recognized the problem, but I can't verify that suspicion- Austria wasn't very forthcoming at the time when dealing with new dramas.)

Other "crack starters" that spring to mind that don't lead to immediate failures: Machining marks, heat treatment micro cracks, Chrome plating, random scratches, corrosion pits...Aside from the Chrome, many of these features can be very small!

[breakeyp]

Something that came up in one of Spinecracker's threads may help explain part of the reason beyond those already listed: Inspection stamp impressions located in the stressed area! The localized deformation is a perfect nucleus for "fatigue failure" in an area that wouldn't otherwise be expected to see large cyclical loads. Little things can make a huge difference!

Link to Spinecracker's thread below, ref. Posts #53 through #58- possibly more.:

https://www.milsurps.com/showthread.php?t=21764&page=6
"New '41 Long Branch..."


Railroad bogeys (wheels, specifically) were one of the first well investigated items where tiny inspection stamps in the web led to catastrophic failures (and some derailments!) long into their service lives. I know that Glock Inc. moved the location of their slide proof marks away from the ejection port for the same reason. (I may have even been the one that first recognized the problem, but I can't verify that suspicion- Austria wasn't very forthcoming at the time when dealing with new dramas.)

Other "crack starters" that spring to mind that don't lead to immediate failures: Machining marks, heat treatment micro cracks, Chrome plating, random scratches, corrosion pits...Aside from the Chrome, many of these features can be very small!

I love the story. My Kinematics instructor at MSU (I can barely define it now) worked on the WWII Bell Aircobra fighter. Propellor in front, drive shaft between the pilot's legs and back to the engine. His two favorite stories (good for at least twice a month) were landing gear breakage traced back to the maker deeply stamping nomenclature on the landing gear strut and the hydro power plant that only lost turbine blades on one turbine. The later determined that the nightwatchman was urinating on the blades on that one turbine!

[Claven2]

Yes, there is a bending moment about the base of the elongated part of the cocking piece, but the forces involved should be more than manageable for a machined and heat treated part, even a case hardened part I should think. Given the relatively low instance of failure, I'm more thinking there was something intrinsically wrong with the specific parts that broke and not a general design fault at play.