Referencing the second gun above: 
http://www.gunsinternational.com/guns-fo...un_id=100964862Pretty sure it's chambered for 6.5 and proofed for PT (1900-1912).  It also seems to have the Zavattero Freres "CZ" mark signifying the Cynea Model (post 1920?).  Barrel SN is 69586 (mid 1930's?).


This is interesting for a couple of reasons as intimated by the confusing info above.  DGS's poster "Builder" in the below line had a similar ZFr Cynea gun for sale on this board for $600...It had been subject of two lines in fact.  It had 6.5 cm chambers and SN 72,621.  And it may even have had Jean Breuil barrels.  At the time we weren't sure of the SN or of the 6.5.  I believed the Cynea model didn't come out until 1920 and Neltir had a 1951 date for ZF SN 97,701 more or less.  
Now this gun appears and we'll have to reevaluate the ZFr SN progression and the dating of his models (perhaps ZFr barrels had a different SN?) or more radical, ZFr alone decided to continue to use cm for chamber stamps until WWII?:
http://www.doublegunshop.com/forums/ubbt...9625#Post489625Post from the above line:
ZFr was founded in 1880 and lasted until 1967. (This gun doesn't have the CZ or FZ stamps which were ZFr models which came out in the 1920's).
I don't know the SN of the ZFr gun we commented on above (previous) line - it wasn't photographed. I believe the guns were consecutively numbered more or less....and will try to expand on this. There's a ZFr gun on Passion la chasse SN 97701 with a comment by Neltir which he dated to July 1951. 
(Graph points: 
.....1880 - 0; 
.....1910 - 49697; 
.....1951 - 97701 ( minus four years 1914-1918)(and 5 years 1940-45)
a graph could be constructed but the SN's for the company must exist somewhere because Neltir had the SN down to the month). 
(
http://www.passionlachasse.com/t22381-identification-fusil-juxtapose