The Sexton

Photo courtesy of the National Archives of Canada.(e000762375)

History :

The Sexton was designed in 1942 and production started in 1943. It was based on the US built M7 105mm Priest which had been very succesful with the 8th Army at the Battle of Alemein in North Africa during 1942. The British General Staff had discussed the possibility of producing a similar vehicle using the British 25pdr instead, as a means of replacing the conventional gun tractor, limber and field gun. It was officially called the Sexton, classification of British Self-Propelled guns had an 'ecclesiastic' theme.

The first prototype was virtually an M7 with a 25pdr gun, but the US were not able to resource series production. The A.E.D.B. (Army Engineering Design Branch) in Canada was asked to build another prototype using the 25pdr on a RAM tank chassis, using the same basic layout of the M7. There were a number of problems with mounting the gun, a new traversing gear was designed for faster traversing and in order to provide 40 deg of elevation the recoil of the gun had to be reduced from 36 to 20 inches. There were also balance problems of the gun mounted on the newly designed pintle due to lack of the trail and carriage as fitted on the field gun. All of these problems were overcome. The prototype was finished on June 23 1942 and was sent for trials at Larkhill in England on January 9 1943 and after minor changes full series production began at the Tank Arsenal, Montreal Locomotive Works early in 1943. The gun and mounting parts were manufactured at the Sorel Works.

The first production run produced 24 Sextons and a further run completed a total of 124, on the Ram chassis, all destined for the Canadian Forces. The UK placed an order for 300 during the summer of 1943 and increased this to 2026 by spring 1944. A total of 2,150 Sextons were manufactured.

Through production there were many changes to comply with the standards of the similar M4A1 tank chassis (Grizzly). Three piece bolted nose assemblies were replaced by one piece cast noses, and various changes to bogie wheel assemblies. These M4A1 based Sextons were the bulk of the British Contracts and included many British modifications.

Contracts were issued with the following census numbers (not complete);
S159377-S159400          24 units
CS172726-CS172785    60 units
CS204782-CS204821    40 units
S233626-S233925          300 units
S233926-S235061          1136 units

The Sexton saw widescale service during 1944 with the British and Canadian Divisions of 21st Army Group from Normandy onwards. A variation of the Sexton was the Sexton GPO (gun position officer) where the gun was removed and replaced by map tables and extra communications and Tannoy equipment. The Sextons replaced the M7s in British and Canadian service which were returned back to the US Army along with all the 105mm ammunition which was otherwise no longer required by 21st AG. The Sextons remained in British and Canadian service until the late 50's at least when most were sold to other countries including Portugal as part of the Nato Mutual Aid Program. Portugal's stocks of Sextons had remained in store until only a few years ago. Only a few have survived with many lying in scrapyards for years eventually being cut up.

Operational Role :

Used by SP Regts in Armd Divs to give close artillery support to Armd Bdes of Armd Divs.

Equipment :

OQF 25pdr 'C' MkII or MkIII gun, sighting gear, observation telescope and protectoscope, 2 machine carbines, 2 Bren machine guns, 2 .303 rifles, No 19 wireless set, 112 rds main gun ammunition and 1,500 rds of .303.
Carried a crew of 6 comprising driver, co-driver, commander and 3 gunners.

Armour thickness :

Upper hull front-3/4", upper hull sides-1/2", upper hull rear-1/2", nose-1.1/2", belly-1/2", rear-1.1/4", top-1.1/4", lower hull-2.1/2".

Specification :

Bridge classification	30
Trench crossing	8'3"
Fording depth	46"
Maximum speed	25 mph
Fuel consumption	1 mpg
Fuel tank capacity	146 gals
Engine	Continental 9cyl radial petrol
Engine rating	400 bhp @ 2400 rpm
Ignition system	magneto
Handbrake	steering (on transmission)
Footbrake	hand parking brake
Track width	16.1/2" (15.1/2" CDP tracks)
Laden weight	57,000 lb
Turning circle	62'
Ground clearance	17"
Ground pressure	12.2 psi
Dimensions	235" x 106" x 96"
Maintenance manual	SXN-LW1
Parts book	25 Pr SP A73

Some pictures of the Sexton during production