The 17-pr gun barrel is approx twice the length of that of the 75mm gun previously mounted. A tank so armed is therefore easily recognisable and when used in support of tanks armed with 75mm gun, is likely to be a target for concentrated enemy fire.
In early October, 1944, G(Cam) Eighth Army were asked for advice on the disguise of the 17-pr gun.

Two methods have been adopted as follows:-

Method A.
A false muzzle brake is fitted approximately half-way along the barrel; its distance from the turret being equal to the length of a 75mm gun. The forepart of the barrel is then "countershaded" with white paint to reduce its visibility. The result is an apparent reduction in the length of the barrel. The use of the false muzzle brake was found essential to provide a clear cut termination of the untreated portion of the barrel.

Method B.
A dummy 75mm gun is mounted on the wireless box at the rear of the turret. When the tank is not in action the turret is reversed. The dummy gun is then at the front of the tank and the 17-pr is concealed with foliage behind. Method A can be employed alone, but its use was also recommended in conjunction with Method B to disguise the 17-pr when in action and to reduce visibility of the portion which cannot be covered when the gun is not in action.
17-prs on Sherman tanks are therefore being treated as in Method A whether Method B is employed or not.
A demonstration of both methods was given at RICCIONE on 18 Oct. It was attended by representatives from armoured formations etc., who were asked to state which of the two methods was preferred. Method A met with general approval, whereas reactions to Method B were, as was expected, somewhat varied.
Objections to Method B included the following:-
(a) The danger of both guns being observed.
(b) The possible difficulty, in close country, of rotating the turret in order to bring the 17-pr into action.
(c) The probable adverse effect on confidence of tank crews of moving into action with the turret and 17-pr in the reverse position. Method B, however, was thought good enough to make it worth while manufacturing dummy 75mm guns for use when thought practicable. It was considered that, whatever its limitations might be, it was at least a good method of concealing the identity of the 17-pr Sherman in any concentration area under observation.
50 dummy 75mm guns have been manufactured up to the present date and 24 have so far been fitted.
Copy of a drawing issued to formations showing methods of painting the barrel and fitting of dummy 75mm gun is shown at Appendix "F".
 

Drawings in Appendix F:	Caption:
	"Method of painting in conjunction with false muzzle brake"
	"Method of fixing dummy 75mm gun on rear of turret"
	"Position of 17 pr when not in action"

Peter's note: "the three sketches in Appendix "F" are scanned from a photocopy of the original at the Tank Museum and tidied up using PaintShopPro. The text is all new as the original was not always clear.
The Appendix also included five photos, showing both Methods fitted to a Sherman Ic Hybrid T-263260 (serial is on left hand side applique armour panel in white, fancy lettering). My photocopy is not good enough to copy again. The photos show (my comments in brackets) -

1. 75mm gun fitted to rear of turret. (front half of tank from the left, which looks almost like a normal 75mm although it sits too far forward)
2. Close up view of 1. (right hand side taken from about 3 o'clock of the tank)
3. Camouflaged 17-pdr. (Distant shot showing how effective the scheme is)
4. Dummy Muzzle Brake on 17-pdr. (close up from left and below of the new brake)
5. General view of camouflage technique. (left front three-quarter view showing countershaded barrel). Note the different styles of 17-pr and 17-pdr, I have copied them as written."

Gun on Sherman Further to Mediterranean Area Technical Report No 26 para 10. Trials were recently carried out by Eighth Army to compare:-
(a) The Eighth Army method of camouflage of 17-pr using a false muzzle brake and simplified form of counter-shading.
(b) War Office design issued by AFHQ as EME Instruction A.984 of 2 Feb 45. WO design for painting was shown to be the more effective and worth the need for extra care involved. The effect was sufficiently good as to make the use of a false muzzle brake unnecessary. This is clearly an advantage as the muzzle brake is not normally a feature of a 75mm gun. WO design now being adopted by Eighth Army and arrangements are being made for repainting of AFVs previously painted under Eighth Army method."
(Peter's note: "anyone any ideas on what this Eighth Army scheme was?")