Gun Fouling

I don't know if this is unique to the carbine model but, I get a lot of smoke fouling around the ejection chamber/port. I also notice smoke residue on the Glock magazine and coming out the load indication holes in the magazine. I'm questioning if this has something to do with the gun being designed as an SBR and the ejection is timed accordingly. It seems to be pulling the exhaust gasses back into the ejection chamber and (this is just a guess) when it racks a round,some of the gasses are forced back down and through the magazine. When I use the same clip in my Glock, I don't get any of this. The load inductor holes are clean.

Anybody else seeing this? Is the bullet potentially loosing some velocity because the bolt extract the cartridge before all the power is burned?

You don't find a lot of fouling with your Glock because the ejection port is totally exposed and vents into the atmosphere. Every 45ACP carbine, rifle, or SBR that I have owned that has a covered ejection port gets a lot of fouling. My HK UMP in 45ACP and my MP5 in 9mm are both this way, lots of fouling. Even more so if suppressed.

MadDog