Then you’ll surely get a laugh out of the fact that the Assault Rifle, SAW, and DMR all shoot 7.62x51mm (according to the Infinity briefing booklet provided with a LE copy of the game) This is hilarious because it is not shown in terms of the balance of the guns. If it were the SAW would be a DMR that is full auto and have a 128 round magazine.
Spartans can lift three times their massive weight and they still get recoil.
Nuff said.
I do like how your information explains the bulky nature of the guns though.
Also the BR is chambered in 9.5x40mm which would make it significantly more powerful than the DMR.
The barrel twist on the AR is 1:7, which is a poor choice for the cartridge it uses, as most weapons chambered in the 7.62 have a barrel twist between 1:10 and 1:12. This contributes to the AR’s poor accuracy.
Also note that the AR is much more accurate and powerful in-fiction than it is in actual gameplay.