7.62x39 MFS 2000 ammo

[GIJOEL]

I shot 150rds of the MFS 2000 brand ammo today and it left the inside of my rifle covered in a light grey/ whiteish film. Is this a sign of corosive primers? The ammo is said to be non-corosive and reloadable (which is why I bought it). The ammo shot well and I got groups in the 2in range @ 100 yards. Could the film be from cheap powder? Or a result of shooting a new barrel that I didn't clean properly?

 

[THE DARK KNIGHT]

It's just the dirty powder, all of that stuff does that. Just give it a good cleaning.

 

[constructor]

I heard the MFS 2000 ammo was .308 diameter, doesn't seem like it would be very accurate in a .310-.311 barrel.