Sound advice there Sage
I've had a few double discharges with an older gun of mine, happened once and I stopped shooting and cleaned it inside and out, action and all to see if I could rectify it but a few shots down the line, it did the same again. But as has been said, not a massive job to correct but with a gun of Cogswell's name, its worth getting sorted to preserve the gun.
I've shot Saga before now and always found them fine to shoot. Didn't get on with them at all, but fine to shoot all the same.
From what you say, certainly from my experience, the primer tends to be push