It a rear seam, post war specs.
Not dated WWII, that be i can do
the only date frame i can give you on this shell is from the 1960's onwards & the chin strap dates from the late 70's onwards.
Nick, I'm surprised you didn't comment on the stainless steel rim... Didn't those stop in late 44-early 45 when the seam was moved back?
shell is from the 1968-1976 period.
Looks Vietnam era.
How odd. I always assumed anything post war with a stainless steel rim was a clone. Learn something new every day on this forum!
also notice it has a fine sand / silca paint texture that dates from the 1950's and after
here's another tip use a tape measure and go over the top from one side to the other, if it measures 18" in or more it could be 1950's, if it's less than 18" total it's a Vietnam era low dome from the late 60's
or it may even be a foreign clone from another country? The IDF / Israeli military may have refurbished it and it could have come from US surplus
Ive seen both steel shells and the liners that were rewebbed by Israel that were of US origin
Interesting; sorry to derail the topic but I've just measured a US M1 I own, a Dutch M53 and a Belgian M51; here's the results:
US M1: 18 1/4 Inches
Belgiam M51: 18 1/4 Inches
Dutch M53: 18 1/2 Inches
Thought it might be interesting to know. I suppose that places my M1 at pre-Nam'.