This is an example of an original issue, probably pre-WW2, M36C. The shell is of course identical to the post-war used M36C, but the liner is quite different.
This original condition M36C is some 50 grammes lighter than the refurbished one shown below - can that simply be down to a coat and paint and a different liner. I wonder....



See the four metal straps securing the liner. Not present on the A and B models.
The chinstrap is much narrower than on the relined examples.


BULGARIA_M36C_liner detail

As you can see here the liner is constructed by sewing small lobes on to a broad headband, quite different from the one-strip liner of the later refurbishments.


BULGARIA_M36C_stamp detail

Ths is the original Bulgarian acceptance stamp, unfortunately unreadable in this case (even if I could read Bulgarian...).



There are three variations of the basic M36, the A, B and C. All superficially similar, but with distinct differences.
The A has a rolled edge, is made of heavier-gauge metal, and has a rather more evident crest. The B is similar to the A except it has no rolled edge, and the C has no rolled edge and a less obvious crest, as well a different method of fixing the liner.
Importantly the number and position of external rivets for the liners is quite different for each sub-type.



This M36C has been completely refurbished since its first issue around 1938. It has been repainted and has a new liner, and gives no sense of having been issued.
That being said, the M36C (and possibly some A and B types) is still in current frontline use by the Bulgarian armed forces, along with the later M51 type and a small number of modern ballistic-fibre helmets.



This is new liner - the original has more distinctively pointed ends to the lobes. See example above.
Note the four internal metal straps which hold the liner band - these are not present in the A and  B model.









Extremely similar to the Italian M33, this helmet was adopted by the Bulgarian forces in the 1950s, but production and issue was very slow, and it equips only about half the Bulgar forces.





There is a slightly different M72, but unless seen with the M51 it would be hard to tell the difference.
This white shell with the P-and-flag logo denotes Bulgarian Military Police.


BULGARIA_M51_vent detail

One identification feature between the M51 and M72 is the size of these vent bushes - the problem is that I do not know which is which. Especially as different production runs of both versions may have slightly different bushes anyway! Information please!

Go to Teo's Kaska page for a better explanation of this.