Cocking Piece Nose/Sear Adjustment

[Bruce_in_Oz]

Some of those "after-market" No4 cocking-pieces may not be such at all.

They may be rejected, scrap or even used and worn ones from bins at the rebuild workshop; ones that never quite made it back to the smelter. It is possible that someone has chanced upon a long-lost stash of "rejects", given them the "once over' in the grit-blaster and blueing tank and voila, "New Old Stock".

I have had two No4 cocking pieces break on me in the last ten years.

At the line of fracture, the crystal structure was like nasty cast iron and the entire forward section was VERY hard.

I suspect that they were WW2 "rush-jobs", done without the benefit of modern pyrometers, etc. Essentially, they were "over-cooked".

BOTH failed during dry-firing of the actions. The internal crystal stresses must have been enormous.

Note that this formation of large crystals is mainly a problem with carbon steels; "age hardening", but not as we usually think of it in Aluminium alloys.. ALL Iron and steel products containing over a couple of percent Carbon WILL suffer from this crystal growth. The higher the carbon content, the bigger and faster this crystal growth will occur.

[Surpmil]

And if you have a lathe but no grinder, some suitable small vise that can be clamped in place of the tool post, or just a four way tool post, could be used to hold the cocking piece against a suitable stone chucked in the headstock.

Could probably get it set up so that they could be swapped in and out using the bottom face as the control surface and do a few at one go.

Trying to make the face glass hard was a favorite trick of some target shooters of past decades. I have seen three or four in parts drawers that were over-hardened and later fractured at the thinnest point.