Lethal, that Mossberg you have is a dang fine gun and one of my favorites. The Howa 1500 receivers are one of the strongest production receivers made. I don't think I typed it the same way my brain was thinking it. [8D]
Goose, you would do much better with a Remington 700 than the Mossberg 100 ATR.
In the under $300 budget there are basically three guns I would be looking at.......
* One of the left over Remington 700 ADL's that were discontinued and replaced by the SPS. Or the SPS if you can find one at that price.
* A Howa 1500 Lightning or hunter model.
* Stevens 200.
Any of these three will be absolutely reliable and last your entire life.