what do you think the proper slug is for a 20 gauge remington 870 pump express mag? and for a 12 gauge remington pump express mag
There are a lot of choices out there and one could spend LOTS of money searching for the best for a particular gun. There are two types I've used that seem to be a great combination of performance/cost. Remington makes a slug called the Buck Hammer that will work well in a smoothbore, and also in a SG with rifled tube or barrel. Not the absolute least expensive, but excellent performance, power and penetration.
The other slug I'd recommend is the Brenneke Foster type KO version . It also is recommended for both smoothbores and rifled tubes and it is priced very competitively. Brenneke is the original make of "rifled" slugs and has been making and modifying them for over 100 yrs. They are excellent slugs.
Do not waste any money on the more costly sabot-type slugs as they are primarily designed for rifled barrels and would not give superior performance from a smoothbore barrel.
When placing a trail camera don't just look for a well used trail. What you want to do is look for a freshly used trail off by itself that goes from a north facing ridge, thick forest, brushy knob or some other similar bedding area to a food source. Don't forget water sources. Especially in the summer months the deer need water so look for a good trail going down too a creek surrounded by thick cover and place the camera 100 yards up from the water source.
Scent control is very important...