Excellent job Popn.  You took a hypothesis and subjected it to a repeatable test.  Great info, and great documentation.

I'm looking into the yellow specs in the AA No.7, I think it is only in the tumbled photos. I will have to see if I can find any in fresh powder.

Great stuff.

I'm really tempted to not bring this up as I know it's going to sound like I'm trying to downplay what you've done.  It's only the possibility that some handloader could assume that your experiment resolves the issue for all loads and all powders and have a serious pressure excursion that leads me to add to the discussion.  You've done a fine job of providing data that the powders tested, in the loads tested, did not suffer visible damage in the certainly extreme length of tumbling you tested at.  There are some factors though that you at least didn't mention evaluating.

Was the powder at all compressed in the loads tested as earlier replies have asked?  If so, the environment the powder grains experienced would be different than in the case of a looser load.  And one would expect the looser load's powder to suffer more damage, leading to more effect from the two factors below.  

Did the tumbling generate any very fine powder (usually called "fines") in the cases?  This would have to come from the surface of the grains, and your photos do imply that if any "fines" were generated, the total would probably not have been very large.  Smokeless powder grains are pretty robust physically.  However, it doesn't take very much in the way of very fine smokeless or black powder to significantly steepen the pressure vs time rise after ignition. Similarly, a change in the statistical distribution of grain size toward the smaller grains will increase the burn rate and burn rate exponent.   After all, one of the major parameters the powder manufacturers use to adjust burn rate is the physical size and configuration of the powder grains.  Steepening the pressure-time curve does in fact lead to higher peak pressures.  Sometimes very much higher.

Many smokeless powders (not to my knowledge black powders, but I'm not certain of this) have a burn rate modifier impregnated into the surface of the grain after the grain is formed.  In the formulations I'm most familiar with, that modifier is often a burn rate retarder which among other things reduces the rate at which the burn rate increases as the pressure rises after ignition.  If that modifier is worn away to any appreciable extent, the burn rate modifier will be compromised, and the burn rate and burn rate exponent will not be what the manufacturer intended.  They will also not likely be consistent or repeatable.

What you accomplished is interesting and your photos of the before and after grains are damn good for any level of equipment, there are though some key factors that from your post you may not have addressed.

Pat

ETA, while I was typing, I see you added the 65% fill info, please disregard that first question.

Myth busted!

Very cool info!  I would also be interested to see 'shooting' data before and after.  I really don't think there would be any difference with normal powders.  Yeah, maybe old cordite stuff.  I also never bought into the 'scare' of a bullet somehow setting off a primer.

Thats a great post.

 To all those worried about a "coating" that will wear off with vibration here are some thoughts.  Many powders are manufactured in foreign countries ie. Australia, Canada, Scotland.  Ever wonder what happens during shipping?  Even domestic powders have to be shipped.  So a case of Ramshot TAC that is shipped (trucked) from MT to say the east coast is going to have the shit beat out of it for about a week.  I submit to you that the abuse on the back of a truck and on a loading dock(s) is way worse than the effects of a vibratory tumbler.  YMMV.

eta:  not to mention the temperature swings...

PLEASE post pics of a .223 round that has been tumbled for 200+ hours. That sucker must be shiny as heck!

Those rocks are ugly

Dumped case


Bottom of case


Bottom of primer

Ok after some searching I have come to the conclusion that the yellow is from my homebrew bullet lube. It was only on the powder that came from the case that had the lubed bullet. Here is a picture of the lube on the bullet you can see the yellow spot.


Here are some odd mutants that I found while searching for the yellow stuff.

Well I believe the media was pretty wore out before I started so it didn't get a mirror finish.

CLICK FOR FULL SIZE

You want photobucket pro.  Trust me on this one.  

I probably have a hundred+ pictures linked in my CCTV thread, and photobucket pro has never even blinked.

Yeah arfcom suck my bandwidth right away and pics wouldn't show so I bought the pro.

I don't see any taggant.  

 

Thanks! The .223 looks good..



 

I wish I had a Oehler model 43 Personal Ballistic Laboratory, I'd run the same sort of test and get pressure results of a control group and the test group.

Good job!  I've done this for years.  Not 205 hours of course, but maybe 2 hours.

I wonder if this affects the pressure at all?

Minor question––––––-Would the results have been the same if you used a tumbler rather than a vibrator?

I would think an actual tumbler, the type that rolls would be even less harmful.



*SPECULATION FROM HERE DOWN*

From observation I don't think there is much vibration actually transferred to the items in the media. The media is constantly moving and very loose, not a good medium for transferring energy, only when the case or cartridge comes in contact with the side or bottom does it feel a large amount of vibration and that only lasts a second. Stick your finger into the media when it is on, you will feel very little vibration.

The vibration, I think, is just settling the loose media. The media at the inside diameter of the tub settles down, the shape of the tub allows for the media at the outside diameter of the tub to "settle up" getting out of the way of the downward settling and this starts the rolling motion. The vibration is an efficient way to get everything moving evenly and constantly more so than to actually hit granules of media against the cases.

The vibratory tumbler doesn't simulate a paint shaker where the contents of a container are being shaken, the tumble is just moving the container though a fluid abrasive media.

Bump for update of fired rounds in OP.

Does the BATFE know that you have a gigantic unregistered suppressor in your house?










 

I don't think it qualifies, it is also very cumbersome to carry when I am out on a "hit", and the bullet trapping effect is a hindrance.

Not if you assassinate someone in the box!








= I am not a lawyer but I think you're going to be alright.


 

This horse can finally rest in peace!  Great research!  

I would like to learn more about this box o silence. Very intriguing!!

Excellent work. Thanks.