Try making up some Bright White Round Targets such as desert size plates for 100 yard targets. Desert Plates are in the 6" - 7" size and should work well with a 3-4 MOA Dot size at 100 yards. For closer Range shooting size your Round White Target so that you can center the Red Dot on the White Target and have a good White Halo around the Red Dot. You should be able to center the Dot on the White Round Target and get a good Zero. Various size Can work well for patterns to mark out targets on card stock. A quick check of cans in the pantry 2.75" Campbell's Soup Can, 3.50" Tuna Can, 4.25" Tomato Juice Can, 6.25" Bulk Food Chili Can. You get the idea.

Spray adhesive works well to mount the dots on cardboard.

I shoot a cast 375 grain bullet in my 480 Super Redhawk. I have a 30mm MatchDot on it which has both a 2 MOA and 4 MOA dot size to choose from. Note: I am using a Weigan Scope Base to mount the MatchDot, not the factory rings. I consider 100 yards pretty much as my maximum range using a Red Dot off Bags.

Bob R