I was shooting my Mauser Czech 98/22 today using some old surplus ammo and when I shot the rife a got some hot gases in my face. I have shot the gun before and used this ammo before and never had a problem. It has been several years since last shooting it. The rifle was clean. I looked at the primer and it was not deformed or flattened. This is steel cased ammo. I did travel by snowmobile about 10 miles before shooting it but it was on a good trail on a windless day but I did not inspect the barrel before shooting. The ammo is always dirty but never gas in the face. Any ideas?