So I've purchased guns online before and this is the first time it's
happened.  Just purchased a USP45T June 23rd from a large and reputable
online retailer and the one received was manufactured in 2013.  Is this
acceptable and standard practice?  I called the online retailer but got the message "Use the
email customer service form, you can leave a voicemail but could take 2
days to respond due to high call volume".  Email sent, I'll report back
what's responded.

New old stock

That's perfectly normal. Unless there are generational changes, like with the Glocks, a several years old example of a current model is acceptable. For example, I bought a Browning Hi Power Mk III last year. New in the box. It was made in 1994. The Mk III hasn't changes since then, so no problem.

The only issue I can think of is night sights. You want those to be new, but it's relatively cheap to replace them.

As said by others, new old stock.  It wouldn't bother me personally as the USP is basically the same as when it was released.  Let us know how it shoots

Shoots like a dream.  Trigger is the best I've ever felt on a modern,
polymer gun.  Literally just putting holes in and right around the
bullseye at 15-20yds.  It outshot an STI Lawman 4.0.



So the common consensus is that it's not a big deal than I'm good with it.  Thanks everybody!

 

New in box regardless of forgotten on a shelf for ten years vs removed from the shelf the same day it was stocked is still new.
Another perspective a 2015 car sold with zero miles in June vs one sold in may 2016 they are both new