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.
One of the things I struggle with when afield is keeping my rifle clean and in good working order. Small amounts of dust and dirt collect moisture; moisture can freeze rendering your action immovable when you need it most. I have seen this happen on multiple occasions, and over time, I’ve learned the cause and how to prevent this from happening.
The first thing that you need to avoid before going afield is leaving excess oil on the gun. Oil will trap dirt and sand in all the wrong places....