Anyone have a kac triple tap on a 16" barrel? I know they work well on sbr's but i don't have one. Can you pin and weld one to a 14.7" barrel to make it legal?

Considering the material they are made out of, not sure if "pin and weld" is viable.  Don't know about silver solder either but as a SWAG that might be a better choice.

The KAC is made of inconel. Inconel is a high nickel alloy. You would have a better bond if the barrel was SS IMO. There are filler metal selection charts available that will let you know what kind of rod/wire to buy when bonding two dissimilar metals.

Do you plan on running a KAC can? The muzzle deflection is increased on SBRs but on a 14.5 or 16" there really aren't many benefits for running one ( other than; hey! check it out I got a $450 muzzle brake ). From what I've read from people that have a TT there aren't any noticeable gains in muzzle control vs a conventional muzzle brake. From what I've read it takes a new cutting head to make each and every TT hence the cost of them.  The hole for the pin would most likely have to be EDM cut or machined.

Inconel is an extremely difficult to work with trying to use over the counter drill bits aint going to cut it ( pun intended ). FWIW I'd contact ADCO and see what they would recommend and how they'd go about it. If they are reluctant on performing the job, there is probably a really good reason why.

I have pinned/welded a KAC TT on a threaded barrel (for someone living in a state that required that stuff). I don't remember the exact length and whether it would take a 14.5” over 16” - but I can tell you you'll need carbide tooling and a rigid set up to drill the Inconel material.