Disclaimer: Please do not try this at home. I can not be held responsible for any loss of equipment or life or anything that happens from you trying this experiment. From time to time we get into a debate about whether it is going to affect your hand loads if you tumble them after they are loaded. We normally get two polar opposites on this one. First is sometimes called “fradey cats”, because like me we head the powder manufactures warning and do not tumble our loaded ammo. Most of the time we use the excuse they are the experts not me. Second are the “commandos” who do not heed the warning of the PhD lab coats working at the powder manufactures and tumble their loaded ammo and say it does nothing, some have even claimed better accuracy. the components. So I am going to try and put this to a rest. I have loaded 12 308 Win cases with 4 different powders using Remington cases Winchester WLR primers and Hornady 168gr A-max bullets. The powders I used are a short cut extruded powder (Benchmark) a Ball powder (WIN 748) a medium length extruded powder (IMR 4895) and a Long Extruded Powder (IMR 4350). The weights of each load was taken from the Sierra “5th Edition Rifle and Pistol Manual of Reloading Data” and are all in the middle of the load range filling the case to right around to the bottom of the shoulder. For the test I loaded 3 each with the same powder charge as measured on a Lyman M-5 (RCBS 10-10) scale. Powder charges are seen in the picture below. I choose these powder for a few reasons 1. It is what I have on hand. 2. I cover just about all rifle powders on the market with ball, short, medium, and long Extruded powders. 3. I wanted to see if one type of powder was more susceptible to damage than another. Winchester 748 43.5gr Hodgdon Benchmark 39.0 gr IMR 4895 40.0 gr IMR 4350 46.0 gr NOTE: Powder seen in photo above is for size and color reference, and it is not for amount of powder used in each load. The test started at 12:22am Tuesday, July 01, 2008 First check will be Tuesday, July 01, 2008 at 08:22am for a run time of exactly 8 hours. This check will involve using a kinetic bullet puller and examining the powder in each case with picture documentation. The same powder will then be placed back into the case and the bullet reseated and placed back into the tumbler for another 8 hours. After 16 total hours of tumble time in a Midway USA/ Frankfort Arsenal vibratory case cleaner loaded with corn cob media the loaded ammo will be removed from the tumbler. All rounds will again be pulled part for inspection and photographic documentation. After that I will neck size all cases (For safety reasons) and reload all the powder back into the case for test firing from a sandbag rest at 100 yards. I will also load 3 more of each and set aside for accuracy results. I will also fire all rounds over a Shooting Chrony F1 Chronograph I will note all velocities and work up Extreme Spread and Standard Deviation using an Excel ballistics calc spread sheet. Clock and ammo in Tumbler. Time 12:21AM Tuesday, July 2008. NOTE: 12 loaded rounds in tumbler.