Honestly, the simples solution is to take the changed canon from deadlock that edits the timeline a bit:
4k before holocaust. 13th tribe left Kobol.
2k before holocaust. 12 tribes leave kobol for the Cyrannus system (in their 10km long arc ship we can actually find - and nuke - in deadlock)...
Also, the Colonials would have experience with heavy fighters because this thing exists in Deadlock:
The Taipan heavy fighter, armed with 2 heavy (for its size) autocannons. Double the HP of a viper and more than double the DPS. So this should be two AC5's on a medium craft if the Viper is...
My only problem with this chapter is that the Colonials would probably have dug into their stockpile of fighter missiles for their showoff to make themselves look good.
Have a screenshot of the pilot then:
All that gray part of the turret just rose out of the hull and yes, a part of it is also sunk into the hull but that's still enough to get a decent amount of superimposition.
And that's besides the point that the ship in the video is clearly the original...
That was actually the engine as highlighted here:
Because you of course need to actually move all those guns and that armor.
And these two blog posts are generally useful for this thema:
where does my main battery go
starships in silhouette
And my only complaint here is that Galactica's...
Yes, Blue water ships are 90+% Gun/Engine/Armour.
But, the two have some really different requirements and around half of that mass in the gun is actually the ammo which as mentioned, the galactica has a lot of.
Well, the Galactica has a sizeable machine shop in her rear area for general maintenance and that's besides all of the stuff in the flight pods needed to maintain the birds. And for magazines and that, lets take a look at these two images:
Well, simply put the Galactica is like 50% ammo and...
Also, a battlestar is supposed to be part of a battlestar group. So behind the flak shield of a jupiter or mercury, you'd have cruiser and escorts to protect the flank and engage enemy ships.
Not actually important for the quest (unless you decide to derp up the colonials) is that they did have quite advanced tech before the cylon war. Their pre-downgrade ships are to the galactica as modern missile cruisers are to ww2 ships.
In the battle for the Tylium Asteroid, Apollo fires his retro thrusters and goes from full combat speed to a dead stop in flash without just blacking out, so yes, some amount of dampening is there.
Only on MK2 as those are mounted on external pods and probably throw of the centre of gravity while the MK3 (and as such later designs) have internal launchers.
Well, BT guns canonically fire in burst while Colonial weapons keep up a constant bombardment while also having deep magazines. Also...