Here is a set of stamps from the RSFSR:



You'll notice that nos. 1 and 3 have what Stanley Gibbons terms "rough perf", while 2 and 4 - the two I've just bought - do not.

This is slightly worrying, since there are several versions of these stamps, the first from 1884 and the last in 1919. These ones are, I am very much hoping, the 1918 set (SG183-6), despite not really looking set-like.

The clincher would appear to be the perforation size: 12½. So far as I can make out, all other perf versions of these stamps are 13½. Nos. 2 and 4 are pencil-marked '12½' on the reverse (annoying) and seem indeed to be so, by my gauge.

So - I've got a complete set, haven't I? (Someone is going to tell me that there is a rogue 12½ perf set somewhere...)