Hello- my 9mm 1911 seems to consider barrel links to be a consumable item. Is that normal? Is it an indication of a timing issue? the link pin seems to drift out a bit when firing. I can tell it is coming loose because of friction with the slide.

Definitely not normal. On the few 1911s I have owned, the link pin would have to be driven out with a punch.

I agree, definitely not normal. Some links will be an an interference fit with the barrel feet. Some will need a punch applied to each end to slightly expand the metal to keep the pin in place. The #13 is a very long link at .291", where standard is .278". You mention " consumable". Is the link being damaged or breaking? Do you see evidence of rounding of the barrel locking lugs or locking lug recesses in the slide? If so, sounds like a timing issue. Kuhnhausen's shop manuals cover the issue.

Once you get the correct length link, it should be staked on both sides. I use a little Loctite also.

Long links can cause all kinds of problems.