Actually, the complaints about the aluminium bedding block stocks are based on the fact that some of them have had serious problems with both loss of accuracy and/or zero shifts due to temperature changes. It occurs because the alloy bedding blocks have a much different response to temperature changes than that of fiber glass, graphite, etc. used in the production of these stocks.
Not all of them do however. The figures I have are 60% have some problems.
McMillain stocks do work as Steelhead has reported. I have done it several times and never had a zero shift.
But, they also can have problems when bedding material gets lost, etc. from being removed and replaced many times over the years. However, apparently even the old M40A1 stocks are still doing well. I saw one in action at my local range doing it's thing. E
