Barkley was not happy with Mullane's violation of their gentleman's agreement and vocalized his displeasure with his former teammate. The Sporting News wrote that Barkley had "all manner of things to say about Mullane." Word of this got back to Mullane and when the two faced off on the baseball field for the first time since their feud began, bad things happened.
The confrontation came in New Orleans. The Browns were on a postseason road trip in late 1885 and faced a New Orleans team that featured Mullane. When Barkley came to bat for the Browns, Mullane "shot one at Barkley's head, giving him a terrible blow in the ear. Barkley in response raised his club and advanced on Mullane, but thought better of it on the way and, instead of striking, cursed him."
The two met again in the spring of 1886, after Barkley had been sold to Pittsburgh and Mullane had joined Cincinnati. Barkley, probably upset with himself for not going through with his assault in New Orleans, made it very clear that if Mullane were to hit him again, he would kill Mullane. Hoping to avoid an on-field homicide, President Nemick of the Alleghenys wrote President O.P. Caylor of the Red Stockings and asked him if he might not have a word with Mullane and perhaps caution him against hitting Barkley again. While it's not clear if Caylor ever had a talk with Mullane, the two men faced off without incident. "So," concluded The Sporting News in May of 1886, "the homicide for the time being at least has been postponed."