I'm not aware of any book on Bill Allard. Here is a tid bit from a magazine article.


Patrolman Bill Allard (ret.),
NYPD SOU, ESU Favored weapon: Colt 1911 .45
NY City Patrolman Bill Allard has been in more gunfights than any other policeman in NYPD history. He was one of the initial members of the NY SOU (Stake-Out Unit) in 1968 and left when the SOU was disbanded in 1973. After leaving the SOU, he continued working the streets of New York in ESU (Emergency Services Unit), Detective Investigations and Patrol, retiring in 1981. He still lives in NY and carries a handgun daily, usually a Kimber 1911 .45. Now 75, he?s finally enjoying retirement after a second career working as a firearms consultant and instructor.
Before, during and after his career as a cop, Bill was a fierce competitor in bull?s-eye. In 1982 he won the national civilian championship at Camp Perry, shooting the .22 and .45. Bill is adamant you must look at your front sight in a gunfight; his years of intensive bull?s-eye practice made focusing on the front sight part of his muscle memory, even under the stress of a shooting. The basics of bull?s-eye (intense focus on the front sight and absolute trigger control) were in his training regimen and carried over into deadly encounters. As the firearms instructor for the SOU, Bill mandated high marksmanship standards for anyone selected, and conducted frequent live-fire drills for the squad. He personally tested and chronographed the loads used by SOU for accuracy, velocity and terminal performance.
Bill has used shotguns, .38 Special revolvers and a Colt .45 auto against armed suspects. The NYPD issued Ithaca 37 12-gauge short-barreled shotguns and buckshot to the SOW. The primary handgun was the S&W 4″ .38, loaded with the (then) NYPD duty load of a 158-grain SWC lead bullet. Bill also carried his personal National Match Colt 1911 .45 with hollowpoints as a backup gun. Because of the nature of the threat and the danger faced by the stakeout squad, members were given a wide latitude in weapons used. Bill had his heavy-barreled 4″ S&W .38 as his primary and carried his .45 in the backup mode, which was specially authorized by the NYPD. Other SOU members carried Browning Hi Powers and additional 2″ and 4″ .38s during stakeouts.
In discussing guns and gunfight survival, Allard advocates the 1911 loaded with a good hollowpoint round. ?In those days (late ?60s, early ?70s), there weren?t many good hollowpoints available. The guys with the Browning Hi Powers used roundnosed ball, which didn?t work too well performance-wise. I had Norma hollowpoints in my .45 ? much better than ball. The .45 hollowpoints didn?t exit the body.? Bill emphasizes sighted fire, 1911s, hollowpoints and lots of competitive practice to give the policeman or citizen the upper hand in a lethal engagement.
During the 5 years the NYPD SOU was active, SOU never lost an officer or a gunfight in dozens of armed confrontations.?

https://gunsmagazine.com/gunfighters-i-have-known/