Combat Arms
                              2869 Grove Way
                   Castro Valley, California 94546-6709
                         Telephone (415) 538-6544
                            BBS: (415) 537-1777
                               May 26, 1991


                    THE SHELF LIFE OF RELOADING POWDERS


          The following material is from Ed Harris on the Firearms
     Echo and relates to the shelf life of reloading powder, an
     important consideration. You can correspond with Ed by leaving a
     message for him in the Firearms Echo. He usually replies within 5
     to 7 days.


     Richard Bash
     -Your SysOp-


                              -=-=-=-=-=-=-=-


          Properly manufactured IMR-type powder will maintain its
     ballistic properties for at least 25 years. Maintaining shelf
     life is dependent on protecting the powder from light - since it
     photodegrades - and heat, which speeds up its chemical
     decomposition.
 
          Ball powders have better chemical stability over long
     storage life, but may not have as good thermal ballistic
     stability. This is because under long exposure to heat deterrent
     may migrate farther into the base grain, changing its ballistic
     properties and, under some extreme cold conditions, combined with
     inappropriate conditions of loading, the individual propellent
     grains may fracture under the primer explosion. This would expose
     the undeterred base grain, thus altering their burning rate.
 
          All powders accepted for U.S. military use are tested for
     long term chemical stability and for ballistic stability under
     extremes of temperature, vibration, etc. Many of the surplus
     powders sold by Hodgdon and others have been at least 20 years
     old when sold as surplus. If properly stored it would still be
     good for many years. 
 
          I am still using IMR4895 made in the 1960s, Hi-Vel No.2 made
     in the 1950s and surplus WC846 reclaimed from Vietnam war era
     production in the 1960s. To all indications the performance of
     these powders is normal in every respect. If you are going to use
     the ammunition up in a year or two, I would have no qualms about
     surplus powder. If you intend to stockpile a quantity of
     ammunition or powder for long term storage, then buy fresh powder
     for that and use up your old stocks for routine practice and
     hunting loads.
 


     Regards,


     Ed Harris