You probably don't want to hear this, but technically, you didn't have all of the requirements. I don't want to explain the gory details of why this happened yet again, so I'll link the second page of
THIS thread.
I will tell you, that the stats server says you got your Expert, and Basic Pistol badge at the same time, Aug 9, 6:41PM. You recieved your Veteran Pistol on Jul 19, 4:49PM. However, I suspect that you got the Vet, and Basic at the same time. But due to the badge glitch, and them fixing it the other night, it took the date from the Expert, because you were still missing the Basic.
Even though the game said you had the Basic, the stats server said you didn't. Most of the stats sites list the highest ranking badge, instead of listing all of them. So you were most likely under the assumption, that you had the Basic.
From what Chuy says, you're out of luck, until you hit 50,000 for the Master Gunnery Sergeant. Sorry man...