Look at all the M1 crowns out there that are oval :) As for the boresnake, you better be pulling it damn straight out of the bore each time.

You might try Pro Shot Products in Taylorville, Illinois.  Their phone # is:  (217) 824-9133.  They sell high quality, but not too expensive, cleaning equipment and chemicals.  I have used their polished stainless steel cleaning rods for years and have noticed no deterioration in accuracy in several rifles.  I always clean from the breech end when possible and use bore guides as mentioned above by MindHunter.  Their jags and patches and brushes are made to fit onto the rod with a smooth joint.  This minimizes the chance of damage to the crown.  The coated rods, such as Dewey's, are no better or safer in my experience.  His stuff is often sold at gun shows and shops around the country.  He has a grease called Pro Gold Lubricant that is exceptional on the slide rails of pistols and even on the bolt carrier of an AR where it contacts the upper receiver.  I use bore snakes for light cleaning at the range but they do not clean thoroughly by any stretch of the imagination.  IMO they are barely worth the time/cost.  

As long as you mentioned the Hoppe's jointed rods I feel compelled to warn you that they are the most likely to cause damage due to two things--the joints and the soft aluminum becomes embedded with abrasive particles which can damage the bore.  The joints are not smooth and the jags are not usually flush-fitting at the end.  They are really only useful to take to a hunting camp to push out bore obstructions and such--in other words emergency use.  Routine cleaning should always be done with a one piece polished rod, which is wiped clean after each pass.  Good luck.