Cleaning barrels with GREASE ! ! !
Bet that title got some attention but yes it is truthful.
The Swiss Army has cleaned their weapons with Automattenfett (grease) since the 1890s if I remember correctly. They have sold us their surplus weapons for last fifty years and I have never heard of anyone buying one with a bad barrel from lack of care.
The Automattenfett was sold by the hundreds of cans ten years ago but we didn't know what it was but alas that is not the only grease we can use.
I use Grease Auto and Artillery GAA and it works very well. I like it because it is a light tan color and you actually know when your barrel is clean because the patches no longer come out black. This grease is synthetic and I have seen it sold on Ebay.
You can also use Grease Aircraft Wide Temperature Range WTR in the same manner. I got that from a retired Special Forces enlisted type that got a commission. I tried it and was quite pleased with how it performed.
How I use it:
For 30 cal rifles I put a 22/25 cal bronze brush on and take a 2" square military cleaning patch and apply grease to it working it into patch. I then wrap it around brush and give the rifle about 20 passes. I stop, unwind the patch and it will be half light tan and half black. I then reverse wrap the patch so the black area is inside and the clean area on the outside and give the bore another 20 passes.
You can also use a 6.5/270 bronze brush, cut the patch into two rectangle pieces and wrap the patch like a barber pole stripes around the brush starting at the nose of the brush and ending up at the base of the bristles.
Oh yes, forgot you can also use nylon brushes.
For other calibers you will just have to find the brush patch combo to give you a snug fit.
I then repeat the procedure with a second patch and a third patch.
What you are removing is the carbon left by the propellant which you definitely need to remove just as soon after firing as possible. Preferably while barrel is warm.
You don't necessarily have to remove the copper from the barrel IF THE BARREL SHOOTS BETTER WITH COPPER IN LEAVE IT THERE.
At the last patch the grease from the patch is left in the bore as the above brush patch should fit snugly so there is no grease visible grease build up.
Thus you have nothing to spill, nothing to leak, nothing to run.