I am looking at uppers on the CMMG web site. Their options for uppers include a full auto carrier. will this work on a semi auto, if so are there any advantages to using one?
Good to know, thanks. Back to the semi auto carrier.:-(Though many will disagree with me, I don't think you're supposed to have a FA carrier in an AR according to the NFA branch and the ATF Federal Firearms Regulation book. This also applies to M16 trigger, hammer, disconnect, selector, etc.
Basically, anything relating to the fire control group (and the carrier is part of that)
Here's a link to the page. The info about the M16 carriers is in the middle row.
Read it and decide for yourself before ordering.
I'm not trying to start an argument and this topic usually does. I will say I'm not a lawyer, but I can read.
General consensus is that the FA carriers are more or less legal as long as no other FA parts are used. Colt currently ships all their Semi-only rifles with FA carriers, so in their case its original equipment. I believe the BATFE has even stated a FA carrier is legal, but like most BATFE rulings it might be open to interpretation.
California has no problem with these.
I live in a free state... My upper was ordered with a FA BCGIt's not so much a matter of NEED, it's availability, and to some extent, reliability.
The FA BC is more massive than the semi BC, which tends to help with reliable, solid chambering, particularly if the rifle is a little bit dirty or underlubricated.
Put it this way...there are no functional DISadvantages to having one in your rifle.
They're also readily available, and often cost less than semi BCs.
There are others that are sold as being F/A BCG and look similar to M16 carriers, but they have had part of the "sear trip" section cut, and are not considered M16 carriers because they cannot trip a sear. Unless they say it's an M-16 BCG, it's not. They BATF has been illusive on this matter; all anyone has said is if it did not result in the production of a weapon that shoots automatically, it would be lawful to posses and make. BCG alone will not make a semi-auto into an auto. Manufactures like Colt, LMT, Noveske, and others sell their rifles with FA BCG and have done so for quite a while. The only part that is explicitly restricted by law is the auto sear, even then you still need all the other F/A internals and cannot use a semi-auto receiver without milling out a portion of the receiver, as AR-15 receivers are thicker walled than their M-16 counterparts.