I've seen people talk about wanting a pellet drop style auger so they don't have a fire in the auger tube.  Knock on wood, this has never happened to me so I don't know what it is.  Can someone explain this to me?  Is it unique to specific grills?

I would think it could happen when you have a flame out and the auger continues to fill the pot and re-ignites creating a fire that is up to or above the level of the auger tube.    Also extreme ash build up could create the same situation.     I have had times when my Traeger has had smoke exiting through the pellet hopper, created by very windy conditions forcing air back down the chimney which could also create an auger fire situation.

I think that I read somewhere that auger fires can occur when you have the pit very hot and shut down suddenly. 

Fire always travels towards an air supply..All fires; camp fires, house fires... A low hopper means air has an easier route to the fire than if it were full, which generates more air flow resistance. ...With an established fire int he pot and the controller turned off, forced combustion air is eliminated unless there is a shut-down cycle . The fire consumes the surrounding air and wants to keep going so it gets its air from the auger, being the easiest place, working its way towards the air supply. Opening the lid negates this as well as going into smoke mode  before turning the pit off.  Most if not all newer pits have a shut-down cycle that has greatly reduced auger fires.  Hope that helps.

I get a lot of smoke back through the hopper on my GMG DC. Its an older model & I've often wondered if pellets in the auger were smoldering. I've always gone through the proper shutdown mode.

I don't think that will be a problem with the gravity fed Louisiana.

Bar-B-Lew you should not have this issue on your Memphis as the pellets slide down a ramp or chute eliminating the connection between your burn pot and your auger tube or hopper

This was a big issue for me after I sold my PG500 and YS640. I ended up with a Blaz'n after learning they have a new shutdown process. My Blaz'n has been rock solid in my year+ of ownership. Knock on wood, no auger fire on any of my units.

Now I prefer having pellets drop into the fire pot. My reasoning is less chance of auger fire.

Bar-B-Lew you should not have this issue on your Memphis as the pellets slide down a ramp or chute eliminating the connection between your burn pot and your auger tube or hopper

I also have a MAK 2, Traeger XL, and Blazn Grand Slam.  The MAK has a 20 minute shutdown cycle.  I don't believe my Traeger has a shutdown cycle and I know the Blazn doesn't.  I guess I will keep the lid open when I turn them off to ensure that those two units never have the issue.  I have not had an issue to date, but I have been reading about people who will not buy a pellet grill if it isn't a chute style which didn't quite make sense to me.

I also have a MAK 2, Traeger XL, and Blazn Grand Slam.  The MAK has a 20 minute shutdown cycle.  I don't believe my Traeger has a shutdown cycle and I know the Blazn doesn't. 

Blaz'n has a shutdown procedure. You should contact Tim. I have had my unit for over a year so I know they have had this shutdown procedure for 15+ months.

take this with a grain of salt.   Buddy with older Louisiana purchased a GMG because the Louisiana kept having hopper smoke and a fire.   So in my limited experience gravity fed doesn't solve the issue. 

DK

I also have a MAK 2, Traeger XL, and Blazn Grand Slam.  The MAK has a 20 minute shutdown cycle.  I don't believe my Traeger has a shutdown cycle and I know the Blazn doesn't. 

Blaz'n has a shutdown procedure. You should contact Tim. I have had my unit for over a year so I know they have had this shutdown procedure for 15+ months.

I think the used unit I bought is 5+ years old.

The only auger tube fire I experienced with my Traeger Lil Tex was when I finished cooking steaks on high and immediately shut down the grill. The "fire" actually made it to the hopper. I say "fire" because there were no real flames, just smoldering pellets. About 10 or 15 mutes after shutting the grill down I had white smoke billowing out of the pellet hopper. The cause is an abundance of fuel and heat in the fire pot and the end auger tube being in very close proximity to that fire and heat. The pellets at the end of the auger tube are ignited by the pellets in the fire pot. Because the pellets in the fire pot are extremely hot, even with the fan shut off, you get natural convection where the heat rises naturally and comes out of the chimney and fresh air is pulled into the grill through the auger tube, just like a stick burner operates. The pellets in the auger tube slowly burn towards the hopper. Grills that have a chute or something that separates the end of the auger tube from the fire pot have a much, much less chance of an auger tube fire. Also a shut down mode severely reduces the chances of an auger tube fire.

Ways to minimize an auger tube fire.
1. Drop to a low temperature, i.e. smoke mode, for about 15 to 20 minutes before shutting down. This burns off the excess fuel that is piled up at the end of the auger.
2. Use the shutdown mode if you have one. It burns most, if not all, of the fuel in the burn pot.
3. Open the lid when you shut it down. This allows the heat to escape much quicker. The faster the heat is removed from the fire pot, the quicker the flame fizzles out. It also adds a new source of fresh air so fresh air being pulled through the auger tube is minimized.
4. A full hopper will reduce the amount of air that can enter the auger tube via the natural convection. Although I think it is helpful, I don't think it is nearly as important as the other 3.

I think that I read somewhere that auger fires can occur when you have the pit very hot and shut down suddenly. 

I agree.  I've had that happen enough times in the past that I now turn the temp down to about 280* and let it get there before turning off (high enough that fan will stay on when you flip the switch to off).
I've also found that if for some reason you decide to abort a cook while the pit is in the start up mode, an auger fire can occur.  I think that is because you turn off the fan while the fire pot is fully loaded and burning around the auger.  Lesson learned=don't abort until the pit is going and cooking temp has been reached.
Now since the change in algorithm for shutdown last year (had to send my control panel to Tim to reprogram), I have had only one auger fire, again because I manually turned off while at 500* instead of turning down first.
By the way, to handle an auger fire on my GS:  I hold down the prime button for about 30 seconds, turn off the pit, and remove and empty the fire pot immediately (a great advantage on the Blaz'n pits) . The result usually is that the auger tube is purged of burning pellets, and the fire pot is empty. == problem solved.  Be sure to wear fire gloves, and use a steel hot ash can.

Bar-B-Lew you should not have this issue on your Memphis as the pellets slide down a ramp or chute eliminating the connection between your burn pot and your auger tube or hopper

I also have a MAK 2, Traeger XL, and Blazn Grand Slam.  The MAK has a 20 minute shutdown cycle.  I don't believe my Traeger has a shutdown cycle and I know the Blazn doesn't.  I guess I will keep the lid open when I turn them off to ensure that those two units never have the issue.  I have not had an issue to date, but I have been reading about people who will not buy a pellet grill if it isn't a chute style which didn't quite make sense to me.

I would not leave the lid open during shutdown.  That allows more oxygen to feed the fire.  On the GS, when you flip the switch to off, when the temp is above 240, the fan stays on until the temp reaches 240, then shuts off, so no fresh air is fed to the fire pot.  If you open the lid more oxygen gets to the fire pot as air is drawn thru the quiet fan and up thru the pot.  I realize that the chimney is still open but with the lid closed, much less air gets in.  With the new shut off algorithm in the GS, you will see a couple of charred pellets in the mouth of the auger tube after successful shut down, but no fire (usually).  And for sure do not open and leave open the hopper lid during a cook. 

I get a lot of smoke back through the hopper on my GMG DC. Its an older model & I've often wondered if pellets in the auger were smoldering. I've always gone through the proper shutdown mode.

I don't think that will be a problem with the gravity fed Louisiana.

Have you checked to make sure your hopper fan is running?  I have a DB, not the DC, but the same principal should apply, and I never have had smoke in the hopper.