Might as well be throwing bricks. Ask KRoyal about his

You can convert 6.8, 6.5 Grendel, and a myriad of other calibers into 5.56 with the same platform. The only difference is that you get to keep the same bolt and so you probably will keep the same BCG. However, you don't want to be running the same bolt on different uppers. You can do it, but the common thinking is that your bolt should be married to the barrel extension. Switching a bolt between them may cause problem due to different stress and wear.

No reason to limit yourself to .300 BO so save a little money and then risk problems.

And then there is this...
https://www.nrablog.com/articles/2016/9/avoiding-the-300blk-ar15-kaboom/

The proof is in the pudding. .300 Blackout is a great hunting round. Just ask my 9 year old son. All animals fell with one shot from the .300 Blackout.









H&R .300 Blackout AAC Single Shot, Silencerco Can, Nikon 3x9 scope using Winchester Extreme Point 150 grain bullet

I would not hesitate to use a 300BO on deer or varmints under 100-150 yards.
With a good bullet designed for thin/soft skinned targets, it does it's job well.
A bonus is only changing barrel and ammo to go from 5.56/223 to 300BO - in most cases - but do check muzzle brake/flash hider and make sure a 30 cal bullet will go thru!
Second bonus is accuracy - if you can shoot it, it will put the bullet where you want it.

For serious hog hunting, where you get on sounders and take multiple running shots, I leave the 300BO at home and take a 6.8 instead.

As for weight comparison between ANY AR and another AR, it's all in how you build it.
I have build brick 223 Wyldes for varmint and paper punching - Also built a light weight 458 Socom.

We killed these 4 pigs late Saturday night. 3 with my blk out and 1 with a 7-08. The misting rain had just let up, and we started seeing deer and lots of rabbits come out. I knew the pigs would be soon. Pigs came to feeder about 2 am, and we let them have it. We did a simultaneous shot, and dropped 3. My first shot killed 2 that I lined up together. I shot another one up the pooper shooter when he was running away, and then finished him off. Action was done in about 8-10 seconds. Distance is about 105 yards to feeder, and the running pig was in back about 25+ yards past that.

Blk out ammo was my 115 grain Berger load, shot out of my AR 15 suppressed with pulsar xp 38 trail thermal scope. 7-08 was a brand new AR 10 and was shooting my 162 ELDX.

Good work

All comes down to what you feel comfortable with