No 221 fuzes

[Gspragge]

I picked one up today by NCR/C
I have one for 1942 which from the marks is a MK 1,
the one today is a MK4, as it has no date, when did it appear
and what might be the differences between them?

 

[sgdbdr]

Hi,

It is described in RAOS V. 4 Pam. 9 Part 1 from 1954

"Mk3 is similar to Mk1 but of new manufacture"
"Mk4 is similar to the Mk3, but manufactured with a stepped shoulder and therefore requires no washer"

Cheers,

S.

 

[TimG]

It is slightly more complicated as the first fuze is a 221 and the second is a 221B. The 221Bs were initially modified 221s and became a separate family so to speak with their on mark progression.

NCR/C - National Cash Register of Canada Ltd.
SM/C - Singer Manufacturing Co., Ltd.

The earliest reference I can find for a 221B MkIV is 1942 - "Prior to June 1942..."

The second fuze comes from empty lot series "5AD" which places it at the beginning of 1945

TimG

 

[AMMOTECHXT]

The washer that sgdbdr references may be the one that was between the aluminium nose cap and top brass time ring of the earlier No 221 fuzes. From those I have found, the washer seemed to be attached to the top of the time ring.