Having had a furniture re-finishing business for nearly 30 years,keeping the customer informed was the #1 priority in my shop. We usually had a 4-6 week turn around time for most "normal" job's,dresser's,tables and such,but if we foresaw a delay,we immediately called the customer to let them know. A little thing like that practically insures success.
Back to the barrel's,I've noticed a slight delay in some configurations,but nothing really bad. I'm now using Rice straight barrels,more expensive than Green Mt.,but well worth the price,fit finish and accuracy and ease of cleaning is OUTSTANDING! Wish I was using them years ago!
I did get 2 "B" weight Colerain barrels at a gun show recently. Must be tough getting barrels as I was asked several time's while walking around with them if I wanted to sell 'em. Maybe some people just don't have the patience for this line of work.