Hi Richard, this pistol ships with (2) 10-Round Magazines. The magazines are not proprietary, it will take standard AR 7.62x39 mags.
Reliable options include brands like Duramag and D&H Tactical, which focus on durability and proper feeding.
Standard Magazines can be found in 10, 20, 30, & 40 rounds.
Drum Magazines can be found in 50 &100 rounds.
It is not difficult to find these magazines, just search for '7.62x39 AR magazine'
budsgunshop.com/product_info.php/products_id/20643/cpd+mag+7.62x39+30rd+matte+black ,
budsgunshop.com/product_info.php/products_id/170994/promag+ar-15+drum ,
Other options here budsgunshop.com/search.php/type/gun+magazines/q/7.62x39+ar+magazine ,
Stay safe & have a great day!

For the Radical Firearms BTR 7.62x39mm 10.50" pistol, the magazine details are as follows:
Capacity & Count: The pistol typically ships with one 10-round magazine from the factory. Some distributor packages may include two 10-round magazines.
Proprietary Mags: The magazines are not proprietary. The pistol features a standard AR-15 lower receiver design and utilizes 7.62x39 AR-pattern magazines.
Higher Capacity: Various manufacturers produce magazines for this platform in higher capacities, such as 20 or 30 rounds. These are generally available through major firearm component retailers.

Hi Richard and welcome. No, the magazines are not proprietary for the Radical Firearms BTR 7.62x39mm 10.50" Barrel. It uses standard AR Pattern 7.62 x 39mm Magazines and Drums which are very common and easy to find. Buds has plenty in stock here: budsgunshop.com/search.php/q/ar15+7.62x39 ----------- Cheers, stay safe and enjoy! P.S., maybe if enough of us make the suggestion, Bud's would add a "Reply" feature as it would make questions and answers much easier: budsgunshop.com/contact_us.php?printForm=reportError