I knew Bill slightly and handled his guns. The barrels on Combat Magnums, whether numbered as Models 19 or 66 or pre-numbered, have always been the same weight.
I'll add that I think the 2.5-inch version was introduced in 1967.
Jordan was quite a hunter. I was in G.W. Stone's custom knife shop, interviewing him for a knifemaker profile that was published in, Blade.
Bill, whom I already knew, came in and told us about his safari, where he had used a Stone Model A knife to field dress 28 head of big game. That included a Cape buffalo, not a small animal! Didn't skin them; left that to the African skinners. But his blade was still sharp, and he was impressed.
BTW, his gun that day was a Model 59 9mm auto! He had driven to Dallas from Shreveport and thought it'd be a good travel companion.
I feel sure that no light barrel Combat Magnums were made. Bill liked the barrel weight, to give the four-inch barrel more of the feel and balance of a six-inch gun. It pointed better and stayed on target better in pointed fire. He even had an old M&P that had belonged to an uncle who was involved in fighting in Mexico, I think during the revolution of 1910. He'd re-barrelled it, with a heavier barrel, to get the effect he wanted.
I don't think the OP (ABPOS) asked about Jordan holsters. Some posting here seem to have misread his post. ??
But I have a basketweave Hume Jordan for a four-inch Combat Magnum and I wore it for a time. I prefer a higher riding holster, like the old Safariland Model 29 or the current El Paso Model 2, which virtually duplicates the older Safariland pattern, or Bianchi's Model 5BHL. These have thumb-break retention straps, easier to release during the draw and more retentive of the gun.
I was able to use Bill's guns, although his stocks were larger than I prefer. A friend had a Model 29 with 6.5-inch barrel and Herrett's Jordan stocks. I fired that with both heavy .44 Special and full .44 Magnum loads. The stocks did a wonderful job of reducing felt recoil. But my own hand prefers Skeeter Skelton's version of Walter Roper's stocks. My own M-29 had factory smooth rosewood "Coke" stocks. The efficiency of the Jordan style was quite evident when firing my gun and my pal's Jordan-stocked M-29.
I saw a photo of a quarter in Bill Jordan's hand. It looked like a nickel in most men's hands! Yes, he was big and tall.
I told him once that I'd wanted to meet him, as I enjoy meeting men whom I could look up to. (I'm 5'10". Bill was 6' 5".). Bill laughed and was modest, as ever. But quite witty in a droll way...
When I ordered my first copy of, No Second Place Winner, I was stationed at a remote radar site in Newfoundland. I told him to hurry and send it, as I was stuck there without much to read. In his autograph, he quipped that he liked a captive audience.

He later signed a second copy of the book, well after I was out of the AF and back in Texas. Elmer Keith later signed a photo of him in the book, too.
Bill Jordan was the fastest accurate gun handler I've seen. He could shoot aspirins off of a table after a fast draw. I never saw him shoot at long range, but am confident that he could. I've seen Joe Bowden and Elmer Keith shoot and I've seen Jerry Miculek on film. Jordan was as good as any, but wasn't primarily an exhibition shooter. He was a cop with exceptional shooting skills. That makes him all the more remarkable.
He told me that in WWII, he was a Marine officer who commanded a unit tasked with mopping up Japanese who'd been missed by the main advances of US troops. Cleaning out their bunkers was dangerous work. He wore a S&W M-1917 .45 and carried a Winchester Model 12 shotgun, weapons he knew well from his Border Patrol service.
ABPOS, I hope you draw images of a Combat Magnum and of Bill Jordan. I think your artistic talent will eventually rival that of A.B. Zhuk. He does the best line ill. of guns that I've seen. He is to gun drawings as Joseph R . Tomelleri is to fish art.