While I have already ordered the first of my dream AR15 rifles (barrel on its way from WOA, BCG on backorder already 12 weeks in). I had a thought while driving down the road the other day.
If you build a competition rifle to be ultra accurrate and ultra reliable (e.g. 3 gun rifle) then way would a battle rifle not follow the same process. With this said I understand you don't want a 15lb battle rifle. And would probably use different optics but shouldn't the blueprint of the rifle be the same?
Mk12 SPRs are VERY similar to 3-Gun rifles, and widely considered one of the most versatile variants.
Minus the weight difference, yes, but in 3gun you will want that 18"-20" barrel for that far steel. I've heard from folks that have had a had time knocking over steel at 300+ yard with 14"-16" barrels.
I think of a 3 gun rig to be more related to a battle rig than a "competition" rig.
When you say "competition" I think of more High Power or CMP type rigs.
It's how you define "competition".
Are you trying to shoot the balls off a bug ?
They should work the same. You lose in competition, you lose your entry fee and your feelings get hurt.
You lose in combat, you and those who may depend on you die.
The CMP/Armalite DMR was a National Match AR with a Daniel Defense 12.0 rail –– that's it.

I keep seeing "tactical rifles" or shtf survival guns....and then custom designed over the top rifles for competition and matches. Got me wondering what the huge difference was. To me I want my gun to go bang everytime without fail first and fit my needs and wants second and seems people around her want to build a "cool" rifle and get mad when it doesn't function.