[Quote]The front ring is Marked Modell 1903 without the knurling usually found on Steyrs; however the side of the receiver is marked "Steyr 1906" - would someone with expertise in the rifles tell me what it is?

Oops, I forgot to tell: This is typical for the military, Greek, production Mannlicher – Schoenauers. "Modell 1903" is the model designation, often scrubbed off by the British gunmakers. Steyr is the Austrian town where the factory was. 1906 is the year the rifle was originally made in Steyr. As I wrote above, Steyr did not sell actions only nor barreled actions to the international guntrade. They sold complete , stocked and sighted rifles from their military or commercial sporter production only. The British gunmakers bought complete military rifles, tore them down, discarded or altered the stocks, scrapped the military hardware and sights and stocked and sighted the rifles to their tastes and house styles.
Commecial Mannlicher-Schoenauer sporting rifle actions can be distinguished from the military ones quite easily: The receiver ring and cocking piece are knurled. The commercial receiver rings are marked "Made in Austria / Patent / Mannlicher / Schoenauer / M1903". The left receiver walls are marked "Oesterr.Waffenfabr.-Ges.Steyr" instead of "Steyr and year of production". Sporter actions have a bolt hold down spring in the right side of the receiver bridge with a corresponding detent behind the bolt handle.
British gunmakers quite often fitted Lyman or Parker –Hale cocking piece peep sights to their Mannlicher and Mannlicher-Schoenauer sporters. Here is a Lyman /inscription removed) on my G.Gibbs "Steyr 1898" dated M95 Mannlicher sporter:

And a Parker-Hale on my G.Gibbs "Steyr 1905" dated M1903 Mannlicher-Schoenauer , both on military actions:
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