I'm in the Remington 870 Wingmaster camp; had mine since I was 16. Shot trap for years on the company sponsored trap team. Shot the usual assortment of feathered and furred critters with it. Got a slug barrel for it, shoots real sweet. Many thousand rounds down the barrel with that gun. Never a complaint with it.
So get an 870 pump, gauge of your choice, take the magazine plug tube out if it has one. Pump guns can hold 5 rounds but the plug cuts the capacity down to 2 rounds plus one in chamber. That's for compliance with most state and federal hunting regs. Yours is planned to used for 'varmint' shooting. If you do plan to hunt with it, leave the plug in. YMMV