Does anyone recognise this M1 Liner Manufacturer’s stamp

[Jimir]

Hi Guys
I have two M1 liners with detachable suspension, one is an eighties Stemaco and I have been unable to identify the manufacturer of the second liner.

Both have the same stamping on the inside crown of the liner, please see picture. One is marked US 78 while the other is marked US 79.

Does anyone recognise this logo?

[ruddersrangers44]

Specialty plastic products was the other 1980's producer both these and Stemaco contain natural light green interior.

[Jimir]

Cheers
The liner (please see pic) has an ink stamp on the inside consistent with a 1983 manufactured Stemaco liner but Mark Reynosa’s Post WW2 M1 book and other information all state that Stemaco liners shouldn’t have a mold mark which is a bit puzzling.

The other liner (please see 2nd pic) has a similar mold mark with a 79 instead of a 78. You can see in the picture that I will attach that the nylon sheets used to make the liner were stitched prior to the liner being molded. Mark Reynosa’s book mentions that this technique was only used in the early stages of Nylon liner manufacture in the 60’s. I do suspect that this liner has been changed to accept the detachable suspension at some stage however. Has anyone come across this type of marking anywhere else?

I can’t find any pictures or information on that particular mold mark on the internet.
There was one posting on a forum from three years ago that talked about M1 liners manufactured in Vietnam having a mold mark with US and a number but I would argue That a 80’s Stemaco Liner wouldn’t have been produced in Vietnam.

[Jimir]

So after hunting around on the internet I came across an identical Stemaco liner with the same mold stamp so the stamp on mine is not unusual.
I’ve examined my own M1 collection and I’ve come up with theory. It’s well been documented in the past that fact that some manufactures have used molds previously owned by other manufactures. I noticed that the stamp in question is very similar to a Firestone stamp from the 60’s (see pictures below) so my theory is Stemaco got their molds form Firestone and removed the F, what do you think?

[Jimir]

Here’s another picture of the Stemaco for comparison

[ruddersrangers44]

Question why are you so sure it's a Stemaco Liner to begin with?as SPP are indentical in colour and ink contract marking,also your theory is correct but as you have read Mark Reynosa's book you will be fully aware that Consolidated molded plastic tool heads were given to SPP so there's no reason why other government lend lease molds including Firestone may well have been loaned to Stemaco,also have you tried both Liners in an M1 shell?

[Jimir]

I’m sure it’s a Stemaco because the ink stamp is slightly different to Specialty Plastic Products and it’s on the opposite side of the liner compared to SPP and it’s vertical as opposed to SPP horizontal stamp also lack of a CMP mold mark in the crown also confirms it’s not a SPP.
The Stemaco fits ok into an M1 Liner but it does have a tendency to fall out of the shell with or without a helmet cover the other one is a good tight fit but sticks out a bit round the edges.
Update
I was going over the section in Mark Reynosa’s book again covering Stemaco and SPP liners and it turns out the answer was there all along but the book contradicts itself and that’s where the confusion arose.
On page 71 it says “ The liners produced by Stemaco contain no mold-in mark in the interior crown” however when I turn to page 72 there’s a picture of a Stemaco Mold-in mark identical to mine and the caption underneath says “Close up of the Stemaco mold-in mark found on the helmet liner, 1983. The mark appears to be US78 above the benchmark indicating a US Government leased mold.”
Need to get new glasses (-: