Welllll....
I have never used their gunsmithing services, so I can't comment on that.
I have bought some AR15 parts from them, and I have had excelent results and I have had complete shit results.
For the most part their AR15 parts are actually DPMS parts.
I bought a chrome bolt carrier, no serations, from Fulton.
Their web site identifies it as "theirs".
The first one I received worked great, I still have it.
The second one did not work.
It was not in spec as far as dimnesions go.
I sent it back twice, they told me they installed it in their test mule AR15 and it worked great.
I compared the specs from the good one I got to the second one, they were off.
Fulton finally agreed to send me another chrome bolt carrier.
It didn't work either.
I posted about it in the AR15 forums and found out there that the bolt carrier was in fact a DPMS part,
When I asked Fulton about it they replied that they "source" their parts from "many major" manufacturers.
They kept trying to pin it on my AR15's and wanted me to send one in so they could "inspect and repair" my malfunctioning AR15.
Funny how that bolt carrier didn't work in ANY of my AR15's.
Someone in the AR15 foruems had the same problem with a Fulton chome bolt and told me to ask Fulton if it was was supposed to be dimensionaly the same as a "milspec" (read everyone elses bolt carriers) carrier.
Fulton hemed and hawed about it for a few minutes and then told me that "custom parts" such as the chromed bolt carrier may need "fitting" in order to make the work.
That being said I have a Fulton (DPMS) A1 upper on one of my AR15's and it works great.
I have bought a bunch of stuff from Fulton and have no problems.
I would buy from them again, but only if I researched the product before hand.
Just for info.