All you need to know about German ammo can be found right here:
http://www.munavia-21.org/indedoc/Lw-Ammos.htmmine rounds = M'geschoß (Minengeschoß)
MGFF/M
Mg151/20mm
MK 108 3cm
As Urchin said they were thinned walled but carried a higher amount of HE content. They were lighter and had a higher MV but lost velocity down range.
They were designed to detonate in the spaces or voids within the aircraft and blow out the stressed skin causing structural failure.
They were highly effective. The majority of their destructive power was derived from chemical energy (high explosives). They didn't rely on velocity at impact to cause damage, they just needed enough energy to penetrate an aircraft's skin. In Ah the damage is more a factor of impact velocity. As such rounds like the MGFF/M (110C-4/b, Bf 109E-4, outboard cannon on the FW 190A-5 etc...) are penalized in that beyond about 240 yards they loss lethality due to their low muzzle velocity (and subsequent even lower impact velocity).
In reality the lower muzzle velocity of the MGFF/M only reduce hit probability, not lethality. There's a similar issue with the Type 99 Mk 1 in AH (A6M2).
The Brits rated the MGFF/M M'geschoß as about equal with the 20mm Hispano round.
Take an AH Bf 109E-4 up and you will see for yourself that:
1. There is no M'geschoß round model in AH or
2. The Ah damage model doesn't account for realistic chemical energy.
The MGFF is now where near 'about equal' to the hispano.
With most of the 'modern' aircraft in ww2 ( to include the 109, Spitfire etc...)
the skin of the aircraft was an integral component in the aircraft's structural integrity. Early A6M2's had anm issue with shedding the skin on its wings in high speeds dives. When the skin failed the wings failed.
The Hurricane had an inner skeleton and the skin was just applied over that skeleton. As such the M'geschoß rounds may explode in the voids and blow away large sections of the aircraft's skin but the aircraft would not fail.
Whether the hurricane had canvass or metallic skin its inner skeleton still allowed it to survive what would most likely be lethal damage on say the spitfire.
Not all rounds were M'geschoß (exception MK 108). The LW used a mixed belt of API, HE-T, M'geschoß etc...
From what I read Hurricanes were more likely to catch fire and burn rather then be blown away by M'geschoß .
Here's an article by Tony Williams entitled:
THE BATTLE OF BRITAIN: ARMAMENT OF THE COMPETING FIGHTERS