i tumble everything... always have... i resize then tumble and have not encountered any issues with deformed cases when the tumbler is full of media... gets the insides of the cases clean too... after removal from the tumbler i give the primer pockets a swipe with a primer pocket brush or the RCBS blade tool... it cleans the crud out and knocks any media out of the flash hole... plus it ensures that i am paying attention to the flash hole to make sure it isn't plugged with media... if you really want things shiny then add a pit of "Polish" to the media.... i use a 50 /50 mixture of walnut shell and corn cob... has worked for me for well over a decade...