Of the two, use the standard Winchesters. The 777 version is reduced power to lessen the crud ring of easily ignited 777 powder. FWIW, I've used standard Winchester 209s to ignite BH209 without issue.
From
Blackhorn website:
Blackhorn 209 is designed to work with standard 209 shotshell primers. For the best results, we recommend the following brands:
CCI 209M
Federal 209A
We DO NOT recommend any of the 209 primers designated for muzzleloaders (Winchester Triple 7, CCI MZL, Federal Fusion, or Remington Kleanbore). These primers are all weaker than standard shotshell 209 primers and do not provide adequate ignition for Blackhorn 209 – especially when used in a poorly designed breech plug system. We also DO NOT recommend #11 percussion caps or musket caps.
