As I'm shopping around for a BCG I'm seeing that many of them are described as "auto profile" or "full auto".  Do these types of bolt make the gun into a full auto gun or is this some sort of marketing hype?  I do not want to build a fully automatic rifle, even if I legally could do so I still prefer semi-auto.  It just seems that there are a lot of BCGs out there with that description, too many to suggest they are actually intended to build a fully automatic rifle.  I don't want to pass up a good deal on a well made BCG because it only appears to be a restricted item.

A full-auto profile carrier will not make a semi-auto gun fire automatically.  What it refers to is the underside of the carrier having the extra material needed to trip an auto sear which is usually milled out of semi-auto carriers.  They are perfectly legal to own and use as long as you keep the select fire fire control group parts out of the gun.

 

M16 is an Auto carrier. The others are Semi carriers.

Thanks, I thought as much but was not 100% sure.  The full auto profile looks a little heavier, is there any benefit to going with a full profile over the lighter looking AR type?

 

EDIT:  If I used a full profile, dose that change compatibility with the receiver or barrel?  The general guideline I'm using for my build is MilSpec and M4 feed ramps.  I do not want to accidentally buy incompatible parts or parts that will not operate optimally.

Thanks, I thought as much but was not 100% sure.  The full auto profile looks a little heavier, is there any benefit to going with a full profile over the lighter looking AR type?

 

EDIT:  If I used a full profile, dose that change compatibility with the receiver or barrel?  The general guideline I'm using for my build is MilSpec and M4 feed ramps.  I do not want to accidentally buy incompatible parts or parts that will not operate optimally.

It's slightly heavier and some say it results in softer shooting but if you're looking for additional mass to slow the action, you would be better served by bumping your buffer weight from a carbine to heavy or heavy to H2.

 

No compatibility change with the receiver or barrel.  When it comes to feedramps, you just want to make sure the receiver has the scallops cut in it to line up with the M4 feedramps in the barrel extension.

The only difference in an auto vs a semi carrier is in the tail section (the part that interfaces with the buffer in the receiver extension) It will have no affect on the chamber or barrel extension. The bolt, cam pin, gas key are all identical.

 

I use auto carriers exclusively, in my experience they are more reliable and subjectively softer shooting.