I prefer the 4-inch round butt K frame for CCW when carrying a revolver, admittedly not that often these days.
When I was first at the FBI Building in Washington DC in 1971, the next to last part of the tour* was the indoor firing range, where an agent fired the Thompson .45 Submachine gun, the Remington 870 12 gauge shotgun, the 4-inch Model 10 with 38 Special loads, and the 4-inch Model 19 with .357 Magnum loads. It was an eye-opener as the agent fired each weapon as fast as he could. Obviously, the Thompson stick magazine was emptied in one burst. They had examples of the four guns fired on display in a glass cabinet on the wall over at the right side of the range.
I was surprised to learn that the Bureau used 4-inch S&Ws as issue guns rather than the 2-inch J Frames. Be that as it may, I decided that if a special agent could carry a 4-inch revolver concealed, then there was no real reason for a 2-inch in a holster on the belt. Thereafter, the 2-inch J Frame became a pocket gun, and a full size gun became the concealed carry gun.
So, to answer your question, it is no trouble to carry a 4-inch K Frame concealed, although the 5-inch Government Model in .45 or the 4 1/4-inch Commander in the same caliber is easier for me to conceal due to the flat profile as opposed to the cylinder on the revolver. That said, if you adjust your wardrobe to accommodate the weapon, it is remarkably easy.
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*As the Bureau in those days was in the DOJ Building, the last part of the tour after the indoor firing range was the inner courtyard where it was explained by the tour guide that "this is where Efrem Zimbalist Jr. comes out and gets in his car at the end of each episode" of "The FBI," a popular TV program by Quinn Martin that ran for about 9 years starting in 1965. On a side note, those that were agents at the time will recall that Hank Sloan, who was in charge of firearms training at the FBI Academy, and Mr. Zimbalist, who played Inspector Lewis Erskine were on the cover of the magazine that the FBI put out to agents and Sloan was shown training Mr. Zimbalist in use of the FBI issue Model 10 4-inch in order to lend authenticity to the show. It is apprarent even in Season 1, Episode 1 that all of the Agents were carrying 4-inch revolvers in Sloan holsters. The hammer protector which prevents damage to the lining of the suit coat is present, which distinguishes the Sloan from the Heiser 457. Starting later in Season 1, Inspector Erskine carried a 2-inch revolver of one sort or another and his holster changed, when using the 2-inch, to a tan Bucheimer spring holster (not the Lewis Police Special copy, but the one with the tension screw).