I left my tumbler on all night,fogot all about it will it damage the brass if you leave it in there too long.

I've done that several times and never noticed any problems (sometimes I do it on purpose if the brass is extremely dirty). As long as you had enough media in it to keep the brass from banging together the whole time I can't see why there would be a problem.

Sealdoggy,

It happened to me once to leave the tumbler on all night. I don't know if it is harmful to the brass or not, but since then I have been using a (inexpensive) timer to set for how long I want the brass to be tumbled.

B.Martins

The motor on the tumbler will wear out before the brass will be harmed. Overnight is commonly needed for heavily tarnished brass.

I haven't run a test, but I would say that tumbling in walnut or corn cob for a week to a month continuously would not make a measurable dimensional difference in cartridge brass.

Would 1/2 hour be OK ?

http://pub36.ezboard.com/fk98kpagefrm10.showMessage?topicID=9.topic Mauser forum

http://www.dcbshooting.com/En/eng.htm military 50 BMG fired cases ,after one year in a wooden box, cleaned with different products.

http://www.balistique-chasse.com/nature/nettoy3.html
Corroded cases: please wait a few seconds for animated pictures showing before cleaning , 1st cleaning 30 minutes, 2nd cleaning 30 minutes

http://www.balistique-chasse.com/nature/nettoy2.html inside cases

http://www.balistique-chasse.com/indexes/indexnature6.html

[ 04-27-2003, 00:54: Message edited by: Edmond ]

"Varmint Al" (he's got a web page) did some test on this and he claims that excessive tumbling will cause "work hardening" of the brass. It probably does but to a degree that has to be almost negligible. I'd be worried about "work hardening" from the sizing operation before excessive tumbling. Some people have way too much free time on their hands.

Overnight is fine...

If you go away for a week or two, that might be a different matter!

1/2 hour is probably too short except for almost clean cases, or if you just want to remove some case lube/etc from it..

Last year I intentionally left some 9mm brass running in one of my Lyman 2200 tumblers, with treated walnut media, for 2 weeks.

The brass was not damaged.