Dating us military helmets
Half-steel half-composite helmet, with the outside shell made of steel and inside shell of composite.There are several models of the liner, either with 2-point or 3-point chinstrap.Also they were fitted with a rim that lost the paint showing the brightness of the stainless steel it was made of.
If this number is between then we have a WW2 era shell.
This shape allows using of headphones and its weight seems a bit below most of Western counterparts.
The liner straps and rivets are rather typical for Russian-made products.
Only limited numbers of these saw service as they were high cost items to produce and as a result this is one of the rarer Russian army helmets. The latter is the designation by the developer, NII Stali.
Weight is 1.6kg" "The official designation is P7 ("? One can see this written by hand near this helmet rim.'6B7' is the first generation Russian composite helmet, produced since mid- or late 90s and up until today. In the field trials, some modifications were proposed.
Probably the last action they saw is Second Chechenian war.