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The specified angle for the angle at the front of the cocking piece is 4 deg. I understand that (perhaps) Envoy/Enforcer and perhaps L39, the angle was varied, to say 7 degrees.
I have two No4 cocking pieces adjusted to 7 deg and intend to try them out.
Anyone got any info on this area?
Predictions on the effect on the let-off weight would be appreciated.
Yep............. the angle of the sear face was changed from up to 4 degrees to 'up to 7 degrees' in order to lighten up the second pull to exactly 5 lbs pull off. According to the EMER's, it was never acceptable or permissable to lower the pull-off to below 5lbs
No doubt the Police experts, in their own 'expert' way allowed it to become less that specified by the real experts at the factory and practiced by the other experts at their workshops............
Together with this, the weight of the sear spring was lowered by the expedient of cutting another slot in the magazine catch to lower the sprung weight.
We had a sort of valve grinding machine set to refinish worn or grooved cocking pieces to 4 degrees or less but not more than
It gets quite complicated............................
my ultra rare classic no4mk2t has a round cocking piece and an EXCEPTIONALY rare windage adjustable rear sight. i bought it from a feeble old lady who only shot it on sundays. she told me her late husband took it off a dead jap at golipoli in 1955. lucky for me, she didn't know what she had.
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http://farm1.static.flickr.com/227/4...4e637e.jpg?v=0
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the feeble old lady:
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http://farm1.static.flickr.com/160/4...e48b17.jpg?v=0
I have to say that modifying the angle on the cocking piece of a previous refurb project thaught me a lot about trigger pull and all that black magic wizardry. (Now I can say I know a tiny little bit about it, compared to nothing at all not so long ago!)
It's most important when/if you do modify or grind the sear to ensure that it is PERFECTLY flat, side to side and top to bottom. If it's not, then the sear cad play all sorts of tricks as it tries to sweep smoothly down an irregular sear bent of the cocking piece.
Obviouslt when we were apprentices, we did them by hand and ruined plenty but out in service, especially at the big Base Workshops, as I said, we had a little sort of valve grinder adapted to do them.
Incidentally, this same adapted machine was also used to grind the faces of SLR and BREN pistons when they got pitted. Just a RCH at a time of course