No4-L42-L39 cocking piece, what's the difference?
After looking at the parts books for the L39A1, L42A1 and the No4 Mk1. I noticed that the cocking pieces are all different numbers.
On my No4Mk1/2 and my L39A1, the visual appearance is similar, so I was wondering what the difference is?
Is it the angle of the face for the trigger weight?
No.4 /L42/L39 Cocking piece details
The Mk 2 cocking piece, CR432, listed for the L42A1 rifle is the same as on the original No.4 Mk 1 (T) but has a modern NATO Stock number, B1/1005-99-961-8206. The front (bent) face is angled at 4 degrees from the vertical.
Referring to the L39A1, The 1971 'User Handbook for the Rifles, 7.62mm, L42A1 & L39A1' states that 'In order to obtain the lower trigger pressures the angle of the face of the cocking piece has been slightly altered': this was to 10 degrees from the vertical (or 100 degrees from the horizontal as PL states). The second recess in the magazine catch is also mentioned.
Spec for 1st pressure: 0-91 to 1.36 kg (2 to 3lb)
Spec for 2nd pressure: 1.82 to 2.04 kg (4 to 4.5lb)
The British NRA minimum is 1.5 kg (3.3lb)
Apparently the first 50 L39s had the 4 degree cocking piece and unmodified magazine catch. An EMER was issued detailing the authorised modifications.