I would like to add that if your broadheads are grouping poorly there is a tune or form issue that need to be addressed.

Even though feild tips and mechanicals are grouping well it doesn't mean they are flying well. If they are not flying perfecrly straight penetration will be reduced.

have you paper tuned or bare shaft tuned??

If the broadheads are grouping well but just impacting diff. than field points, and you can't get them to match then you can readjust your sights or go with mechanicals.

Just remember mechanicals should not be used as a band aid to other problems.