If you didnt pull the nipple, give a good clean and rinse, you may end up with rust down the road. Leaving the nipple in may not give it a good flush, plus you are not flushing out the threads.
I use one bucket to clean, one with clean water to rinse. An easy way to get the water out is run a couple of patches thru, then pour rubbing alcohol down the barrel, dry patches and then oil the crap out of the barrel.
I have a 54 Renegade that I have owned since '89 and the bore is spotless. If you are not absolutely certain that you got all of the BP residue out, you didnt and thing will rust.
