A copy and paste from the Queen's Royal Hussars museum facebook page. decribing some first hand use in Korea.
C Squadron engage the enemy.
Let me state that the 20 pounder main armament is the best tank gun we have had so far. Once my Troop spent a week sniping individual CHINAMEN at a range of 3,600 yds with a most satisfactory degree of success. (One morning we got two before breakfast). It will put a shot into a bunker mouth at a 4,000 yds, once ranging has been completed, although it may take up to three shells to put one right in. Therefore 4,000 yds is considered the economic maximum for pin point shooting with High Explosive (HE).
However, the fragmentation of the HE round is poor. It appears to fragment in strips the length of the shell. I have seen two Chows bisected nearly at the navel, it's true, but on the other hand I've also landed a shell about six foot from the heels of a fleeing Chow and he showed NO effect other than a surprising degree of acceleration.
Their effect in a confined space such as a bunker, however, is little short of atomic, as the bunkers are mostly well stocked with blast grenades which go off too. During op COMMANDO I poked my nose into a bunker in which I had seen a shell land. I counted five heads, some round, some flat, some attached, and some detached. There was too much mess for one shell, so I suppose a good supply of grenades went up too. It is therefore good policy to put 'em in the door where possible. The other good point about the 20 pounder shell is that you can't hear it coming. I once, as a tank OP (see Tac) got a little close to the receiving end of our own tank fire and 20 pounder rounds arrive without the well known whine. They crack overhead like outsize bullets. In spite of my faith in the 20 pounder and the tank gunners of 8th King’s Royal Irish Hussars, this was a rather unsettling performance and is worth bearing in mind when supporting Infantry.
The rate of fire of the main armament is also good if, firstly, it is possible to "load off the deck“ and secondly the gunner and operator "fire on the trip". Loading off the deck is self explanatory, the rounds being passed off the back deck to the loader by the driver. Firing on the trip means that the gunner keeps the gun on the target and his finger on the button. The loader then fires the gun when he trips the (safety) trip switch. By this means my crew often had 5 shells in the air at once and fired 50 rounds in 8 mins. Then the loader fainted from the fumes which causes toxicity poisoning.
If firing intense, therefore swap the loader with the driver at the third “clear‘out" of empties. (We normally cleared after every 10 rounds). Naturally it is NOT possible to load from the deck when moving or when incoming mail is close, and under these circumstances the rate of fire is greatly reduced after the first 10 rounds. (I carried 50 HE, l0 AP, 4 smoke per tank bomb load). There is one point more which is well worth a mention. Wherever it is at all possible, travel with the gun in the crutch when not in contact as travelling with the gun to the front causes excessive wear on the elevating gear. This results in excessive play in the gears which in turn leads to inaccurate shooting. For the same reason it is advisable to stop the crew from doing chin-ups on the gun, or traversing half RIGHT and using it to pitch a bivvy. (This latter practice particularly infuriates Gasket).
And so to the Besa coaxial mounted machine gun. Now the Besa is on the LEFT of the main armament on the CENTURION, and it has a RIGHT hand feed. The belt comes over the top of the MG and round a roller. It has NOT proved a satisfactory feed, as the belt tends to over-run, and end in a heap on the floor. This has two answers. One is to replace the roller with a metal spigot, which causes more friction; the other is to mount a bracket on the RIGHT of the MG and below it.
During the April battle on the Imjin the need for a second MG was felt, as angry little men climbed on the top of the tanks and beat on the hatches with fists and rifle butts. One answer was to charge through a mud house, but this was NOT thought to be the real answer, as it increased the shortage of houses already made obvious by zealous gunners. It was thought further that it was better to stop people getting on in the first place. Therefore .30 BROWNINGS were obtained, rumour has it at high cost (in gin), and mounted on the commanders cupola. This has a dual advantage in that it solved the problem of the angry little men, and also prevented crew commanders from being garrotted by signallers, with their customary homicidal tendencies towards tank men. The fury of the Royal Signallers knew NO bounds as their now harmless tight wire traps were time and again swept serenely aside by the advancing tanks.
Personally I cherished NO animosity towards the Sigs and contented myself with merely immobilising 3/4 of Seouls tram car service by laying claim, vi et armis, to some 200 yds of overhead wire, which I took with me for some four blocks. Fortunately for me someone preceding me had touched the same wire and blown the fuze, or I might have got summary justice. It was hanging low anyway.
So much for the .30 BROWNING - a useful gun. Now , smoke dischargers. These have never been loaded since the April battle as a chance bullet set one off, and it dribbled all down into the engine and set it on fire. The tank was lost. I expect the Chow responsible got a Mention in Dispatches.