It establishes a chain of ownership from the U.S. Government to you - a provenance.
Bob
"It is said, 'Go not to the elves for counsel for they will say both no and yes.' "
Frodo Baggins to Gildor Inglorion, The Fellowship of the Ring
It certifies that that serial number rifle was sold by the CMP. In most cases it states what grade is was sold as (ie. Collector Grade / Correct Grade / Service Grade / Field Grade / Rack Grade ). To some it adds value, to others perhaps not. The older certificates used to include the name of the buyer, they stopped that practice a while back I believe.
As of March they were still putting the purchaser's name on the certificate.
Bob
"It is said, 'Go not to the elves for counsel for they will say both no and yes.' "
Frodo Baggins to Gildor Inglorion, The Fellowship of the Ring
Also remember that a "lack" of grade on the certificate usually meant service grade as a default...
To some folks who are not experts & are just looking for a good shooter, it increases the price they are willing to pay. A lot of them have seen junkers that have been abused, or have import markings, or that were are Bubba specials; they know with CMPpapers, they will be getting at least some level of quality.
A CMPcertificate will assure you that it is not a welded receiver. Other than that it is worthless to anyone but the original purchaser because everything else on the rifle can be changed or modified by subsequent owners.
This may not have anything to do with this, but I was perusing Gunbroker and there was a seller who was selling M1's and he specifically was adament that in each rifle's description he stated that "these are not CMP
returns". The way he stated it was like implying that the CMP rifles were inferior to his that he was selling. I am not saying what he was selling was junk (although overpriced), but I think he is remiss in doing this. To me, just like mentioned above, the certificate legitimizes what the rifle is when the initial seller got it. If the rifle was a collector grade then so be it....it. is. If the certificate states that rifle was a barreled receiver, then you know you got a parts gun that was put together. It sorta irked me that the seller of the rifles on GB described them as not being those CMP rifles. I really don't think he will get the prices he was asking. I always have doubts when I see M1's on GB that don't have the CMP or DCM certificate.
Mike
I do not have any "grade" typed on my recent certs (1 RG, 1 FG, 1 SG special). It is listed on the invoice though.