I would call first. If you do sent it in, go to the Hi-Point website, click on "Contact", you will see a link to the form to fill out and print it to sent with your firearm. It makes it easier since it has all the input info needed along with a section to describe your problem.
When I sent mine in, I placed it the original box minus the lock, papers and just sent in the gun and mag. I placed a copy of the form in that box. Then I placed the original box into a slightly larger box with another copy of the repair form in it and used shipping tape, lots of it, to seal it securely.
Took it to the local USP shipping store, insured it for $200.00, stated I was shipping machine parts back to manufacturer (as advised by Beemiller/Hi-Point).
Cost me $9.45 shipped UPS Ground, they received it the next morning, but we only live appox. 50 miles from Hi-Point.
I have only a couple hundred rounds through it. I plan to get at least 1000 through before it gets to cold here in northern IL. I'll wait to see how the trigger is after 500. If I do have to send it to the mothership, I want to do it in the winter when I can't go out and shoot. Thanks!
I've also got a C9 with what feels to me like a very heavy trigger pull. This is the first handgun I've owned, but I've owned many long guns over the years and this C9 has the heaviest pull by far. I've also shot Glocks, Rugers, and one other C9, all of which had much lighter trigger pulls. Hopefully it lightens up after a few more rounds, otherwise I may have to send it in.