Advice for them as likes to replace bucking bars
For them as likes to replace bucking bars with a length of hardened bolt, please do yourself a favor and use the shoulder part of a shoulder bolt. Opened one today (that also wasn't getting much grease in the area) that had a threaded bolt in there. Bolt was nicely finished at the ends, but the shaft had worn large enough to get your pinky finger in there. Shaft also was scored with grooves that looked the same spacing as the threads on the bolt. Looks like those threads chewed it up pretty good.
Sometimes I sets and thinks, sometimes I jes sets.