Though I can see why old canon sources get "uncanonized", new stuff added tends to conflict (for example, PPC minimum accurate range was originally because "PPCs are heavy, their weight limits their target tracking abilities against fast, small machines." (Which all mechs are considered 'reasonably small' as at the time it was written the tallest one was slightly over 13 meters [MWO's Hunchback, the shortest 50 ton medium is 13.6 meters, and that height range of barely over 13 meters included Atlases with giant heads]). All ACs also had minimum accurate ranges, too. Though a large part of this was because short of the Awesome, every PPC carrying mech of medium or larger size actually had them as hand-mounted, detachable rifles. That was 1987.
Left, 55 ton tank in Crysis.
Center. 55 ton Shadowhawk as scaled in Battletech, 1987, which roughly matches to the Dougram at 9.63 meters tall.
Right. 55 ton Shadowhawk as scaled by MWO. Over 15 meters tall. [Atlas is 17.6 meters tall in MWO, but 'barely over 13 meters' in BT].
Interesting, isn't it? Now with that size difference, the whole "climbing on a battlemech to pop the hatch, shoot the pilot and yank out the corpse" thing isn't that far fetched, now is it? With sizes like that, helicopters, tanks, etc. are very realistically threats against 'Mechs just like they are stated to be. Anyway back on the PPC canonization rant.
1989, Clans were introduced. With ER PPCs in the picture and new people doing the rules, the reasoning had yet to be rewritten but would soon need it. ER PPCs for the IS originally still had the "too heavy to swing around" issue of 90 meter minimum range. Clans didn't with their 6 ton ER PPCs being snapped into the arms that couldn't 'swing' at all. Less issues to accuracy supposedly. This is still before the unseen.
This wasn't very fair.. At all. So it got changed (assuming in the early 90s). As it happens, the unseen issues also came. Many hand-mounted weapons ceased due to Harmony Gold issues. So came the rewrites: IS ER PPCs lost the "too heavy" thing and got no minimum range. Regular PPCs got field inhibitors. Then, "PPCs are explosively volatile and require field inhibitors to degrade the performance to keep them safe." Leading to "It needs to charge up to fire." With an option to turn that off, with the risk of thing blowing up in your face and the pilot losing consciousness from impact or heat exhaustion. (That's just firing 1 PPC, or 1 at a time for a series). Furthermore, most of the 'hand held' weapons kinda stopped.
Griffin with laser, and Hatchetman. Btw, can you see the Patlabor influence in this late 80's shot?
Right down to the helmet. Even the hangar is also practically identical (the catwalk was removed, since BT mechs are slightly taller and are not 'carried' into battle on the backs of 'super-transport' trucks). Many combined arms campaigns in the late 80s / early 90s are heavily Patlabor influenced, too. Vehicle-bound spotters, command cars with relay equipment, etc. came from Patlabor. Seismic Sensors came from 08th Mobile Suit Team, a gundam universe series. Jumpjets, also from similar sources.
Back on the de-canonization rant.
o.O; Of course, this leaves the "Why are ACs still burdened with minimum accuracy ranges in TT?" Haven't found the Catalyst Games answer yet. But evidently Wiz Kids changed it to "minimum ranges for ACs mounted on torsos only." Because sluggish torso twisting, I guess. At this point I'm just shrugging my shoulders. Though I will say since IS mechs generally have pivoting heads and arms with both upper and lower arm actuators it seems perfectly reasonable to believe that IS mechs could make up for their lack of manueverability through the use of arm-mounted weapons, especially with ~many~ references to straightening out their arms to fire overtop of short buildings and 7 meter walls, as well as pre-3000 use of cover based tactics and 'blind fire' by sticking their arms out beyond walls to fire toward the enemy (popular with the 'giant explosive machine guns' that are Autocannons).
So far I've counted 5 different companies owning the Battletech series. They are not all that good at being consistent or backtracking through the lore, so.. in essence they reinvent it for their purposes. Akin to what I believe PGI has done. Thus for the most part I stick with FASA's lore. They made it first, regardless of who says what is canon now, we know FASA's crew came up with the originals and went to great lengths to keep it as realistic as possible. (There's even custom rules for infantry sniper fire for taking out enemy pilots in mechs, and details on a number of weapon variants which include different laser variants of the same category that range from "0.1" second beam times to "2 second" beam times... with advantages either way).