Destructive testing a Ross MkIII

[Ridolpho]

Interesting thread! By coincidence, just the other day, I stripped the bolt on my un-pinned MarkIII and learned how to assemble it incorrectly. First thing I learned was how to do it correctly for which the instructions in the old Canadian government manual (1913) are far and away the clearest. That manual doesn't even mention that 1/8 of a turn backwards when the "plain cylinder just enters the sleeve" allows the bolt to be incorrectly configured- but why should it? It's so obviously wrong that they must have figured no one tasked with stripping a bolt could conceivably be dumb enough to insert it in the rifle like that (time proved them wrong, I guess). But my question pertains to an unstripped bolt- has anyone been able to cause the bolt to enter the sleeve incorrectly without stripping? With mine, the extractor won't allow the bolt head to rotate far enough to enter the sleeve incorrectly. If it could that might explain how an infantryman might get into trouble just cleaning the assembly.

Ridolpho

[browningautorifle]

It was never just cleaning, it was stripping and incorrectly assembling...that was the problem.

[ForgottenWeapons]

It takes a bit of force, but mine will snap around the wrong way after being assembled correctly. The extractor has enough spring to ride over the bolt head as I rotate it.

[boltaction]

The old adage "you can make something foolproof, but not damn-foolproof" applies. It is possible to assemble the bolt incorrectly, and ForgottenWeapons is correct in that with a fair amount of force and determination, a bolt can be snapped around when assembled. However, it then takes some fiddling to get it to go into the rifle smoothly, etc. So, by forcing things they can be made to work incorrectly, but only but forcing things, and that should usually be the first clue to anyone that maybe something "ain't right".

Ed

[Surpmil]

I have never found a MkIII bolt that will slide smoothly into the rifle with the bolt incorrectly positioned.

What other modifications did you make to the bolt OP, to get it slide so smoothly?

Post a photo of the bolt head showing the end of the extractor slot please.

[Patrick Chadwick]

The Ross Book has a chapter on M10 blowups written by an engineer, Dupris. You seem to be plowing old ground.

Like the majority of non-Ross experts, I have not got the book, but have got a PC. I knew about the nasty possibility, in an academic way. But the video makes the point unforgettably. As for ploughing old ground - aren't we doing that eternally on the forums anyway? Because we have forgotten, or because we don't know. AND for the enlightenment of those who ask for help.

[Surpmil]

So ForgottenWeapons, did you modify the bolt or bolt head to get it to slide freely in the misassembled position or not?

[ForgottenWeapons]

The only modification I made to my bolt was to grind out the safety rivet. Here's a photo of it assembled incorrectly:

Attachment 43522

In order to get the bolt smoothly into the rifle when mis-assembled, you just have to pull the bolt head forward slightly, so that the locking lugs sit horizontally. While this is a clear indicator of a problem to someone familiar with the Ross, to a green recruit, I think it could be overlooked as simply the bolt being a bit fiddly to put back into the rifle. After all, you do have to be a bit careful positioning the bolt head when doing it correctly, to avoid having it snap closed under spring tension before it's fully in the receiver. For someone who remembers that it take a bit of finesse but doesn't recall how or why, I think a misassembled bolt could be installed without being obvious that something is amiss.

[Surpmil]

The only modification I made to my bolt was to grind out the safety rivet. Here's a photo of it assembled incorrectly:

Attachment 43522

In order to get the bolt smoothly into the rifle when mis-assembled, you just have to pull the bolt head forward slightly, so that the locking lugs sit horizontally. While this is a clear indicator of a problem to someone familiar with the Ross, to a green recruit, I think it could be overlooked as simply the bolt being a bit fiddly to put back into the rifle. After all, you do have to be a bit careful positioning the bolt head when doing it correctly, to avoid having it snap closed under spring tension before it's fully in the receiver. For someone who remembers that it take a bit of finesse but doesn't recall how or why, I think a misassembled bolt could be installed without being obvious that something is amiss.

Well, to get the bolt head into the position you show it in, it has to be taken apart and put together incorrectly, or the bolt head has to be pulled out and rotated with the extractor out of its slot, in which case it can with a bit of luck, bad luck or practice, be slid back into the position you show; if there is no 'safety rivet'.

You mention that the bolt head must be pulled forward slightly so that the locking lugs sit horizontally and this is my experience also. The problem is, they never sit horizontally on the Rosses I have examined, they sit at about the 2 o'clock and 8 o'clock positions, rather than the "9 & 3" that would allow the bolthead and bolt to slide into the action freely. At the "2 & 8" position, the bolt head binds on the left side rail as the force of the spring pulls the bolthead backward in a counterclockwise direction (seen from the firer's position so to speak) making it just about impossible to slide the bolt onto the guide rails, let alone into the breech.

In rifles with the extractor slot ending in a 'ramp', it is easy to rotate the bolt head into the wrong position, but in rifles like yours with the square-ended extractor slot, the extractor must be pried out of its slot to do this. The ramp-ended slot was a design defect, but I haven't seen it on a MkIII rifle, only on M1910 sporters.

So are you saying that your rifle bolthead sits in such a way when misassembled that it will slide freely in and out of the breech?

"One more unto the breech, dear friends?"

PS: is there an ETA on the video by the way?

[ForgottenWeapons]

Yeah, my bolt head does sit at 8&2 when misassembled. I found it fairly easy to hold it forward at 9&3 while getting it into the receiver grooves, and once you have it seated you can let go of the bolt head and it will slide pretty well. It's not quite as smooth as a correctly assembled bolt, but the difference is slight enough that you wouldn't notice unless you set up up both ways one right after the other.

I have all of the video done except for actually firing it out of battery - I'm working on coordinating with another blogger who has professional quality high speed cameras. If I can't get that set up in another week or two, I'll do it with my own consumer-grade high speed gear...so the video should be out by the end of the month.