The brackets are https://amzn.to/37PJbA3. The smaller screws that came with it were about 1/2" but I used 1 1/4" instead. The wood is pine, 1.5" thick.
My concern is whether these screws will shear or will get pulled out of the wood, after a long time of using the bed (frequent getting in and off loads, tossing and turning over night, etc.). I was wondering if I should switch these to structural screws of the same size, or bolts/nuts/washers so that they go all the way through these vertical side rails and can't be pulled out of the bed.
I asked someone at a big box store and he said what I have should be more than enough and the small screws are just used to secure the brackets to the wood and not really carrying the load, but I figure of course they are carrying the load being transferred from the brackets. He also said drilling all the way through for bolts may split the wood.