I know it's close to deer season, and guessing that's why you have that setup. I have the identical, and it has run perfectly since day one. Not that it helps you any. Some barrels need a little breaking in, some don't.
What I would do is first, put your factory barrel in and see how it runs with your spring set up. If flawless, try some more rounds through the LW, and see if it starts running properly.
Lets face it, if your using it in a couple of weeks, for gun season, the first shot, is the one that matters most, and, it's too close to season to resolve with sending it back!
After the season, if your not happy, send it back, but before you do, contact JR, and tell him your concerns. He is top notch, and will make it right. Good luck!
If guns kill people, then, I can blame my pencil on my spelling!