Honestly not sure...the few I have been able to get have been going into complete uppers......I am working on getting a decent supply
Manufacturer specializing in both DI and Blowback pistol caliber uppers. www.maconarmory.com
45 ACP, 45 Win Mag, 460 Rowland, 10mm, 40S&W, 9mm and 7.62 Tokarev.