Basic waffle
You can’t play the Chieftains aggressively,
for the 8.7 chieftains
their guns are extremely potent, dealing with most armour without thought, only T-72s/64s which you only face in an uptier make your gun struggle,
don’t charge headlong into the enemy, wait for them to push you, your Lower Front plate is very poor, and easy to hit, try to hide it as much as possible,
as for the upper front plate, when not angled downwards while hull down, its dependent on the gun, whether or not it pens, while in a hull down position it is rarely penned.
as for the turret, most things shouldn’t be able to pen it, but there are guns that can, but all but the highest performing rounds will need to aim to penetrate,
As for it’s mobility, its poor, and the jump from the mark 3 to the mark 5 is noticeable, [/details]
Yes the Mobility is Poor, yes the hull is weak, its a great tank, the gun is strong, in addition to its relatively strong turret its great
the gun is perfectly fine at range, and 8x zoom is enough to use for all realistic ranges you’ll be sniping at (0.8-1.6km), while yes, they don’t have laser rangefinders, (while there is some that will claim that the Mk.5 should, AFAIK that comes with the Mk.5/2) they have optical rangefinders, which is perfectly fine to use , and accurate enough to use, especially with the APDS, with HESH maybe not so much (but who snipes with HESH?) the Chieftains look like they do poorly, they are in reality great vehicles, but definitely have their own playstyle
having had a look at your replays you didn’t do anything wrong with the tank,
just general gameplay related things, like paying attention to your map, and knowing where to aim (see the TAM and Strv 101 (3 shots to kill while side on?) from the Campania Replay), and listening for enemies, also you don’t need to retake your cap on battle, it does nothing toward winning the match , and try not to overextend away from your team, and why first spawning the Mk.3 when the Mk.5 is just plain better?


also heads up, you don’t need to use your machinegun that much, it gives your position away
the Mk.3 is a lot worse than the Mk.5, (as your stats naturally reflect), also in addition, on the Mk.3 do not use the Dozer blade, it provides next to no protection or benefit and adds nearly 2 ton to the already overweight chieftain (making it 1.5 ton heavier and 100hp short of the Mk.5, rather than slightly lighter and 100hp short)

(I see you bring 22 APDS + 2 HESH, personally i bring 20 APDS and that being it, but there’s nothing wrong with your ammo load)
Their certainly not the most natural tanks to get a hang of, but slap when you do get the hang of them
(my stats to show i'm not talking utter bollocks)