I built a .458 Win Mag awhile back and used a A&B barrel. It built on a FN modelo 1935 peruvian Mauser. It was pretty much a budget build, decent walnut stock, peep sight, stock bolt handle and safety. I couldn't see spending a ton of money on a barrel for a rifle that I was only building to mess around with. I did pretty much all the work myself with the exception of opening the bolt face. That said it has been a pretty good barrel. When it was new it fouled pretty badly, but it has seen probably 300 rounds now and is much better. Its fairly finicky about bullets, it wont shoot barnes well at all solids or x varieties. Accuracy is fair, I don't expect a tack driver out of a .458 Win Mag either though. Its usually groups 3 shots into 2 1/2" or so at 100. I consider that pretty good for a peep sighted big bore.
Are A&B the tops or equal to that? No, certainly not.
Could they be seconds from E.R. or others? I would wager that very likely based on what I have heard.
They are simply okay. They shoot alright. They give a guy looking to build something options when they might not have the scratch for a top flight barrel. They also give an opportunity to avoid a good deal of 'smithing $$ by providing short chambered pre-threaded barrels.
If I spending money to build a once in a lifetime custom, or a real accurate rifle I would certainly choose something higher up the food chain. In my case I wanted something to mess around with on a budget and thats what A&B helped do.
You get what you pay for.
