could someone tell me how many sizes farquarson rifle actions came in? and what would be the approximate maximum calibre for each size including custom rebarreled rifles?

According to Frank de Haas's book Single Shot Rifles And Actions they were made by several different companies; Gibbs, Bland, Jeffery, and Westley Richards to name a few. He states that John Amber made Farquharson's will do nicely for 600 nitro express. Gibbs is the most common Farquharson action. There is little reference to the size variations. De Haas has other books out that may tell more. Mr. Single Shot's Gunsmithing Ideas Book of his may be another place to look. If you're thinking about building a rifle on one you'd be better off using a Ruger No.1 as the Farquharson's are very hard to come by and extremely expensive. Gun Digest No.17 (1963) has a fairly large article on them but only mentions the original black powder chamberings and the .303Brit.
Good luck in your search.

/

ALF

you are right. I looked at a friends rifle's. both the 500 nitro, the little 303 and the 375 H&H are built on the same action size. These rifles are built by different companies.

I belive there was an Beligan company who made some of the action as a sub contractor for some of the British makers.

The farquarson is like a bulldog, soo uggly that it's charming

kos---

I've personally seen four sizes of Farquarsons and two completely different styles.....hammer fired and striker fired..... There seems to be no standardization of size, design, or parts.

The size to pressure ratio is not comparable to modern alloy steel actions. That means you should use a bigger than normal action for small but intense calibers.