Need help identifying US M1 Helmet

[EmptyingTheAttic]

The shell l apears an original M1 but the paint looks to be vietnam and Thats a vietnam period liner also, not ww2, it looks like 1978?

I should preface this by saying I already have the information I needed on the helmet/liner (and now know it isn't the WWII souvenier I'd hoped). 2 days ago a helmet was a helmet to me, but I've learned from here that the subtelties that distinguish them are many. So this is just partly for my curiosity, and partly other motives (*see note below).

Am I correct in my understanding that 'Era' and actual war dates are not the same? That a helmet or liner style remains called that until a new design replaces it?
I've assumed this because the Vietnam war ended in 1975 yet a 1978 liner is still 'Vietnam period' helmet.

*NB: not only curiosity, I have to confess that as it turns out that the helmet has no specific family relevance I see no point in hanging on to it and will probably end up ebay-ing it. So I'm picking your brains for a different motive now - felt it only fair to mention that and will fully understand if you don't feel inclined to reply.

[battle gear]

your grandfather probably picked it up at a surplus store or flea market within the last 20 years

I would consider it a post Vietnam era helmet from the 1980's thats when most of these were sold at surplus stores

[NickD]

if you're going to sell it, sell it as a late 1970's to early 80's US M-1 helmet don't try to pin an exact date on it or possible conflict use but also these versions of the M-1 aren't as sort after as WW2 to Vietnam era helmets but you might be lucky to get £30 for it.

& also the liner is not Vietnam era as it has the detachable type of webbing this type didn't come into use till post Nam conflict.

[EmptyingTheAttic]

Many thanks for the advice - much appreciated. Yes I probably will sell it.
I've family from both sides of WWII and heard a lot of interesting stories growing up, and have since inherited a few interesting items that I cherish because of knowing something of the stories behind them. But a random helmet isn't of interest to me so I'd rather sell it to someone who is interested in it than just stick it back in the attic again.

Again, many thanks.