Rifle Scopes S&B 3-20 Ranging Marks - Why 50cm?

[jerkymeister]

I came upon a Schmidt and Bender 3-20 and is has the reticle depicted below. Mostly normal mil scope, although the ranging marks are rather odd to me. Per the data sheet, these markers are for 50cm (~19.7 inches) at 200-500 meters. Seems like an odd choice of size, and I'm wondering why they decided to use 50cm. What real world references are 50cm, to make best use of the reticle?

A large car rim is close, human head is way too small. Any ideas?

 

[TheOE800]

Average male shoulder width or something IIRC.

 

[jerkymeister]

Average male shoulder width or something IIRC.

They are vertical, so maybe not?

 

[TheOE800]

Ah that would have been a key detail to notice.

 

[Center Mass]

I was researching this for one of my S&B's and came across this obscure image reference. Take it for what it's worth...

CM