The Roundel pattern was primarily used on C grade guns from around 1900 to 1905 and only about 25% of Cs from that period are engraved in that style.
The common feature of these guns was the prominent line borders that hook on the bottom of the gun on rear of trigger plate. This style is attributed to Joseph Loy.
Here is an example. A CH upgrade done in this pattern by Gournet.
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