Tumbling loaded ammo THE TEST
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.
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.
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.
Why would you tumble loaded ammo?
Matt- most common reason is to clean off case lube. Be interesting to see the outcome of this. Might also try some 45 ACP loads to see what happens.
This is actaully quite interesting because this issue comes up a lot with the real accuracy hounds of reloading. There are plenty of arguments, both for and against, so I will definitely be interested in seeing the final results.
I know cpttango30 has at least one real good boltgun, ( :D ) so the results on the accuracy at the end of the project will be a very good bench mark.
Regardless of the outcome, this should probably be moved to the Knowledge Base upon completion, with the other posts moved down and his results placed in order, for future viewing and consideration.
Excellent idea cpttango! Here's hoping no ill effects come out of the tests.
Pulled all bullets and inspected powder in pan and back of bullet. The Benchmark shows a very slight amount of “dust” on the back of the bullet. The Winchester 748 showed the least amount of “Dust” on the back of the bullet. The IMR 4895 shows slightly more “Dust” on the back of the bullet along with visible dust in the powder pan. The IMR 4350 showed the highest amount of “Dust” on the back of the bullet and in the powder pan.
08:22 hours time to remove loaded ammo.
The “Dust” I am sure is from the powder and not the case as the Benchmark “Dust” was the same green color as the powder. There for, I am going to say while it is not a significant amount of “Dust” and I did not see a single broken kernel the fact remains that something is happening to powder in a tumble. Weather it is able to be seen with the naked eye cannot be determined at this time. For more accurate account of what is happening, the powder would need to be inspected with a microscope.
I called Hodgdon Powders tech support line this morning to ask about coatings. The tech said some powders are coated with graphite, some with inhibitors and some powder are coated with other chemicals and some are not. I did not delve into which powders are coated and which are not and why. This throws a big red flag up for me in the tumbling of loaded ammo. If the dust I am seeing from all the extruded powders is this coating you very well could be affecting the burn rate of your powder.
Also I noted damage to about 25% of the polymer tips of the Hornady A-max bullets. Ammo went back into the tumbler for another 8 hours.
Pictures below are after 8 hours of tumbling.
Missed one Win 748 picture.
Bullet with powder Dust on it.
The pictures above really give no indacations if the powder is being damaged. That being siad in this last picture you can clearly see a ring of what looks like dirt it is powder. For this reason I am going to forgo the shooting of these rounds as I feel the point is proven that you should not tumble loaded ammo. If you are knocking it apart in the case I believe it is better left to a rag to clean off lube. A rag and some break clean or gunscrubber will do wonders for resizing lube. I will provide one more update at the 16 hour mark this evening.
Inconsistent bullet weight seems like it would be just as big a problem as degraded powder, especially when using soft points.
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