Is by using a pull thru.
http://www.amazon.com/Hoppes-BoreSnake-Revolver-Cleaner-Caliber/dp/B004DPGM1O I use one between courses during a shoot to keep the bore match ready.
There were two styles of cleaning equipment issued with the M1 Garand. The early was a screw together rod that was stored behind the trapdoor in the buttplate. The other, late model , was a pull thru that used a small weight attached to a cord, on the other end was a threaded attachment for the cleaning jag. The breech is opened and the weight is dropped into the bore to fall out the muzzle. a patch with solvent or oil is attached with the jag and pulled thru from breech to muzzle.
This system was adapted after discovering that the rifleing at the muzzle was being worn out by the use of the rod without a guide.
Oneshooter
Armed and Livin in Texas