Try a wire cone shaped brush for inside the field points. Don't use oversize points, use 11/32 points, not 23/64 on an 11/32 size shaft. Clean any paint of taper, or sandpaper to roughen the surface.
I have used Bohning and Hot Melt glue gun with good results. I put the glue on the shaft, then heat the point, push it on and turn with pliers to spread the glue, then wipe off the excess. Spin test the point on a piece of wood, and cool in water, and spin test again. Heat the point with a butane torch, or alcohol flame, don't use candles because they give off wax.
I have a Yellow Jacket foam target, and found that it likes to pull off points, in spite of what the saleperson said. Some targets are better for broadheads only. I like a Block, or similar target when shooting field points.