25pdr AP Rounds

[keith.brigstock]

Hi Guys great forum

Can any help me resolve a debate on the introduction of the muzzle brake on the 25pdr.

Am I right in saying the Mussel brake was introduced to facilitate the use of Charge Supper when firing the 20Ib AP round as up to that point they had to use charge three.

If it is true where is it stated in which document and if not what was the reason.

[Quatermass]

To quote Hogg, British & American Artillery of WW2:

...the only significant change was the adoption of a two-port Solothurn muzzel brake in 1942. This was done at the suggestion of the Chief Superintendent of Armament Design in order that the Super charge could be used with the 20lb armour-piercing shot; originally this shot was only used with charge three, but the increased thickness of German tanks led to the proposal to use charge Super, whereupon it was found that the gun was unstable because of the high recoil stresses. First trials with a muzzel brake were carried out in April 1942, using a German brake adapted from the 105mm leFH18M design; this showed the equipment to be much steadier, but all the tracers in the shot were extinguished as they left the muzzel. It took some time for this to be tracked down and turned out to be a fault in the filling of the tracer and nothing to do with the muzzel brake at all. In July 1942, the Solothurn design was tried and recommended for issue, and in the following month, Director of Artillery recommended equipping all guns with the brake...

Also see: List of Changes. Para B7830 of 21 July 1942.

[keith.brigstock]

Thanks Quatermass

Its that very peace of righting we are try to prove. We have not been able to find any official documentation that states that "AP Shot is only to be fired with Charge Three" or words to that affect. A number of the veterans we have spoken to state that they always used Charge super if it was available in the Desert before muzzle brakes where introduced.

So it tring to find that document that states what sould be used as we cant find it.

[Quatermass]

Gander states this:

...the addition of a muzzle brake when an armour-piercing shot was introduced into service after experiments in late 1942. To provide this shot with the maximum punch an increment was added to the supercharge and this increment took the gun over its carriage safety limit. The addition of a four-port Solothurn muzzle brake threaded onto the muzzle reduced the firing stresses to a manageable level.

Ganders incorrect about the AP shot being introduced in 1942, its part of the statement of ammunition 1940.

25 PR Mk I (18/25 PR). Three charges.
25 PR Mk II & later. Three charges & Supercharge
25 PD Mk II & later with muzzle brake. Three charges & Supercharge + Super increment.

Looks like the muzzle brake allowed the use of Supercharge with Super increment in the Mk II and later guns. The Mk I gun had no Supercharge option.

Source: Handbook Q.F. 25-PR., Mk I (1940). Q.F. 25-PR., Mk II (1940). Q.F. 25-PR., Mk II & III (1944). Outlines WP1 25 pounder gun-Part 1. Terry Gander.

[Quatermass]

To quote from the 25-PR range table, A.P. projectiles. 1943.

A.P. PROJECTILES (Weight 20-lb.)
SUPER CHARGE plus INCREMENT
This charge must ONLY be used with Guns fitted with Muzzle Brakes.