Is there a difference in the quality of Rem. 700 barrels, new today vs. 5-10-20 years ago? How 'bout quality of an el cheapo 700 ADL synthetic barrel vs. a Sendero barrel vs. a BDL vs. a stainless barrel? There seems to be so many take off barrels available for 700s and I have an older ADL action (long) that I want to do something with.

Next question...is the taper, etc. of say a stainless 7MM-08 sporter barrel the same as a 30-06/.270/.280 sporter barrel? (short action/chamber vs. long) I'd like to have another .280 and finding takeoff .280 barrels is next to impossible. Thought about getting a new 7MM-08 Stainless takeoff barrel and having it rechambered to a .280 or .280 AI.

Finally how is the quality of a Rem. 700 barrel vs. say an Adams and Bennett barrel? (maybe I'd be ahead if I just want a shooter to buy an A&B barrel, but I assumed the taper will be different.)

Thanks in advance!

There are a lot of barrels on ebay. I bought a 7mm08 varmint barrel from a friend at the range for 50 and put it on a 1971 action and it shoots terrific. Shot is Sunday for the first time and got a .6 group with nine rounds in it.
I can't answer all your questions but maybe some smiths will chime in here.

Barrels can be good, bad, or indifferent in quality no matter when they were made. The steel in the blank, machine adjustment, operator error- it is a crap shoot. Rechambering a 7mm08 to a standard 280 will require more than just running a reamer in to depth, because the shoulder diameter of a 7mm08 is to big to clean up with a standard 280 without setting the barrel back a couple of turns at least.