Just curious if that name "Circle 10" was/is unique to Arsenal.
I have 5 of them with the "10" with 2 circles around the number I bought years ago from Kvar.
There is no "Arsenal" brand name on them anywhere?

Arsenal is really just an importer. For the purposes of importing some rifles they established a facility to de-sporterize imported Bulgarian and Russian rifles. The ((10)) mags are Bulgarian.

"Circle" (10) is the proof mark for a particular factory in Bulgaria.  I have an AK74 mag which is marked (21) -  Circle 21.  I believe that another factory is (25) that also made mil spec /  contract mags.  (10) seems to be the most common in the US.

Circle 10 is the nickname they received here in the US market, it is the arsenal stamp for the state owned arsenal in Bulgaria that produces them. Arsenal Inc is a US based importer that imports the products from Bulgaria.

"Arsenal Inc" is the US importer, "Arsenal Jsco." is the actual manufacturer in Bulgaria (yes the ((10)) company).

The 'real' Arsenal even meets NATO standards for manufacturing weapons/ammo/etc.

The Arsenal that is in the US (mostly just imports), does make a small number of parts for 922r compliance (hand-grip, stock, forearm, muzzle-device, etc), but the heart and soul of their guns are imported (barrel, bolt, carrier, trunnion, receiver, etc).

Of course it all gets really confusing, for awhile, "Arsenal Inc" was importing large numbers of Izhmash and Molot AK rifles from Russia. But people would routinely refer to THOSE as "Arsenal AKs"... Because the name they seen on the box or in the description was something like "Arsenal SGL-21" ... So people were all over the place when it came to who/where/what made their AK... Then often these SAME GUNS, being marketed as 'Arsenal Saiga SGL' were often imported by "Fime Group" ... which created even MORE CONFUSION, and people would get aimlessly upset if their gun didn't have the name "Arsenal" associated with it and somehow believed that "Fime" represented inferior quality (which it didn't).

Of course this is the norm for the gun industry in the US. All the time I meet people that bought a gun, they tell me about it and I'll know more about their own gun than they do.
Me: "Ah that's made in Turkey right?"   Them: "No it's made by Rock Island Armory!" ... *looks around on the actual gun* "Oh, hmm, I guess it is made in Turkey..."

I believe '10' was the Warsaw Pact 'country code' for Bulgaria, as '2' was for Hungary.

Arsenal, Fime, & K-Var, are different branches of the same company. GARY.