The Smith & Wesson is well used, banged up — kind of ugly, actually.

The nickel finish on the single-action revolver, made around 1875, is pitted and eroded, the hard-rubber grip badly chipped from being dropped.

But as Newport Beach, Calif., gun collector Ron Herrick put it, “It’s how a gun was used that makes it desirable.”

And this particular .44-caliber pistol purportedly was used to kill none other than the outlaw Jesse James.

When the gun is auctioned off today in Anaheim, it could set a record for a Western historic firearm, experts say.

“The James gun is really something,” said Anaheim’s John Robinson, one of Orange County’s top collectors of guns from the Old West. “It will set a standard.”

The Jesse James gun could fetch $300,000 — smashing a record $240,000 paid in 1998 for a pistol used by outlaw “Blackjack” Ketchum, said John R. Gangel, president of auction organizer Little John’s Antique Arms Inc. in Orange, Calif.

Gangel acquired the gun about six months ago from a collector who bought it for $160,000 at an auction in England in 1993.

Bob Ford, a later recruit to James’ gang of bank, train and stagecoach robbers, killed Jesse James on April 3, 1882, in St. Joseph, Mo.

Ford fired once into the back of James’ head as James straightened a picture while standing on a chair in his living room.

The outlaw, 35, had just finished breakfast with his wife and two children. His guns were on his bed. His 7-year-old son found the body.

James spent 16 of his years as an outlaw, gaining a romanticized reputation as a revenge-minded family man who took on railroads for the benefit of the common folk.

Although some scholars have since come to dismiss James as a ruthless, pro-slavery killer who kept all of his ill-gotten gains for himself, his name remains as instantly recognizable today as the etching on the pistol that killed him.

That etching reads, “Bob Ford killed Jesse James with this revolver at St. Joseph, Mo., 1882.” Ford conspired with his brother, Charlie, to kill James. Railroads and politicians put up $10,000 for the hit.