Which brings us to two more unofficial modifications to the Denison smocks. The 1st pattern smock lacked the additional snaps to secure the tail-piece when not in use and led to many removing it completely to avoid having it dangle down in the rear. The knitted cuffs in the 1st pattern were appreciated for being windproof and led to short lengths of hose tops (socks) being sewn to the end of the arms on the 2nd pattern by some. As for David's "match grade" ammunition comment I'm not sure if he is referring to a specific match grade manufactured ammunition or simply referring to ammunition that is known for its accuracy.
As an amusing aside and speaking from personal experience, there is a large BritishAirborne reenacting community in Texas which prefers the 2nd pattern smock as it is cooler to wear when running around the countryside playing silly bugger in the Texas heat. When I used to reenact I'd go 'commando' under my 1st pattern smock and wool trousers lest I suffer from heat stroke. Now there's a 'modification' the Sergeant Major would frown on!