Black wavy marks on brass

[stello1001]

Hey all,

This is a first for me. Anyone have any clue how these marks got here? The marks are on the cases after having spent an afternoon dry tumbling in rice. I suppose it's possible they were there prior to going into the tumbler. However, I cannot recall me making that observation before. This is on factory ammo 6.5 grendel.

I also have other cases there from reloads that are tumbling in the same rice simultaneously. These other cases are 6.5 creedmoor and do not show any signs like that.

Any clues?

 

[Edsel]

If it's doughy to borderline sticky, that might be from starch (rice powder) + oil.

 

[Kickin45]

 

[stello1001]

If it's doughy to borderline sticky, that might be from starch (rice powder) + oil.

I think it kinda is. Any reason why it would only stick on the grendel cases? That's pretty weird and a first for me.

 

[Edsel]

I think it kinda is. Any reason why it would only stick on the grendel cases? That's pretty weird and a first for me.

Not sure.

Some powders leave more residue than others, I suppose.

Tulammo .45 ACP residue, for instance, always had this strong Ammonia smell and tended to be hygroscopic.

Just a guess.

But I strongly suspect that gum you have there is a mixture of starch and something else.

 

[stello1001]

Thank you...

I replaced the old rice last night with new one and cleaned the bowl. I'll see here soon if they got cleaned up.

 

[spife7980]

Quicker to take some steel wool to it if it is the gummy stuff

 

[stello1001]

Quicker to take some steel wool to it if it is the gummy stuff

That could've been a good solution too. I swapped out the rice last night and left the brass tumbling. This morning I checked them out and the 4 or 5 pieces that had the black residue now had less. Last night it was very stuck that made removing it with my fingernail tough. This morning, it scratched off real easy.

Thanks everyone for the info. I thought this was very odd and strange but I guess it's happened enough that others knew about it right away haha. I'll add it to the list of things I've now learned from reloading.

 

[straightshooter1]

I think it kinda is. Any reason why it would only stick on the grendel cases? That's pretty weird and a first for me.

I've been using rice for many years and have not seen that on any of my cases, but I might make a guess:

You're rice has been used a lot and is really dirty now; need changing to new rice??? A picture of the rice you used would help with the diagnosis.

Those particular cases have more lube left at the bottom of the grendel cases after sizing, leading to the accumulation of powder residue at that location (in addition to the above)???

 

[stello1001]

I've been using rice for many years and have not seen that on any of my cases, but I might make a guess:

You're rice has been used a lot and is really dirty now; need changing to new rice??? A picture of the rice you used would help with the diagnosis.

Those particular cases have more lube left at the bottom of the grendel cases after sizing, leading to the accumulation of powder residue at that location (in addition to the above)???

The rice is some Asian rice recommended by Greg from primal rights. I got it off Amazon but do not recall exactly which one it is.

The rice was indeed somewhat dirty but not nearly as dirty as I usually let it get before replacing. Never had this issue before with dirtier rice.

None of these cases were lubed. After going over the ziploc bag notes where I had my brass, both (factory grendel cases and factory creed cases) were once fired as factory ammo. I was doing the initial cleaning before sizing so they're still un-prepped other than the tumbling.

The only thing I can think of, the bowl was dirty from many tumbling cycles. Last night I gave it it's first cleaning, actually wiping it with rubbing alcohol. Perhaps all the gunk just happened to accumulate on the grendel cases.

My creed cases are good quality Peterson brass and were already fairly clean. So maybe the gunk couldn't stick to those since the surfaces were clean and smooth. I have no idea, just spit balling haha. My grendel cases are S&B, and while fairly consistent in the SD numbers (for mass produced ammo), they still shoot quite dirty.

 

[CK1.0]

Rice sucks for tumbling IME. Rice leaves a weird film on the cases and gets dirty too fast. Like most stuff Orkan/Greg from Primal Rights says/recommends, it’s not fully vetted and is arguably bad advice and better left ignored IMO.

Get yourself some 20-40 grit corn cob blasting media, it pours out of the cases like water when you’re done and cleans much better.

 

[stello1001]

Rice sucks for tumbling IME. Rice leaves a weird film on the cases and gets dirty too fast. Like most stuff Orkan/Greg from Primal Rights says/recommends, it’s not fully vetted and is arguably bad advice and better left ignored IMO.

Get yourself some 20-40 grit corn cob blasting media, it pours out of the cases like water when you’re done and cleans much better.

I will consider this and shop around for it.

I liked the idea of rice because of the minimal dust it creates. How has corn cob been for you in this regard?

 

[CK1.0]

I will consider this and shop around for it.

I liked the idea of rice because of the minimal dust it creates. How has corn cob been for you in this regard?

Honestly, the corn cob blasting media is pretty dusty; it's sort of "garage only" versus something you'd want in the house... it's fine grit stuff, 20-40 grit blasting media is way finer than most corn cob tumbling media that most of us are familiar with.

That said, it really does work great, but the biggest thing is that instead of having to beat the crap out of the brass after tumbling to get all the media out of the cases with a media separator or whatever, all you have to do is turn them upside down and let the media pour out. I just put on a pair of nitrile gloves and can hold ~10 cases upside down in one hand between my fingers while my other hand picks them up. It only takes ~2 minutes to go through 100 cases.

Since I started doing it this way, not having to beat the crap out of the cases post-tumbling has noticeably shrunk my average SDs, it's pretty nuts how obvious it is, as the difference shows up in the chrono numbers and downrange.

 

[softcock]

I been using Hazelnut tumbling media lately, it super hard and clean . There is online dealers that get it from.
I not adverse to walnut, but there is just and over abundance here in my area with hazelnut because it one of the bigger crops being produced local.
.

 

[memilanuk]

having to beat the crap out of the cases post-tumbling has noticeably shrunk my average SDs

If you're having to 'beat the crap' out of your cases post tumbling with rice, you're doing something wrong - like the wrong grain size of rice. Smaller, shorter grains work better and come out pretty much just like corn/walnut, with a regular rotary media separator. The 'milled' stuff that Primal Rights sells works even better in that regard, but holy f$ck it's pricey. I tried one bag just to see how it worked; afterwards I went down to the local Ace hardware and got a hand-cranked grain mill. Plan is to try milling my own next time from cheap, locally available rice (ie Costco/Walmart/grocery store). Guess we'll see if that works as expected.

Otherwise, yeah, I do agree that corn cob is pretty goof-proof. Just dustier than I care for. But it does get the cases oh-so shiny