So I'll be the first to admit that I'm still learning the ins and outs of firearms.

I have my first suppressor coming in and am looking for a lightweight rifle to be it's host. So currently I've been looking into either a 300 blackout or 308.

What I'd like to use this gun for:

1. Subsonic fun, Plinking and target
2. Supersonic hunting

Questions I have about 308.

1. I have heard you need a faster twist rate that usually comes on 308 to stabilize subsonic like a 1:10. Which then limits you to heavier bullets on the supersonic side?
2. 308 subsonics are less consistent because of the larger casing size?
3. Subsonic 308 can have issues with unburnt powder? (I don't reload, is this just an issue with reloaders or factory subsonic)

Questions on the 300 blackout.

1. I'm looking into a bolt action because my understanding is they are usually quieter for the shooter vs a gas gun. Is there truth to this or should I look into a AR15 since the 300 BO was built for that platform? Is it a bad decision to go bolt action on a 300 blackout.

Current thoughts, I like the idea of having a 308 over a 300 blackout because 308 offers more in a supersonic situation, However, I have other firearms that would make up the difference if need be.

So I'll be the first to admit that I'm still learning the ins and outs of firearms.

I have my first suppressor coming in and am looking for a lightweight rifle to be it's host. So currently I've been looking into either a 300 blackout or 308.

What I'd like to use this gun for:

1. Subsonic fun, Plinking and target
2. Supersonic hunting

Questions I have about 308.

1. I have heard you need a faster twist rate that usually comes on 308 to stabilize subsonic like a 1:10. Which then limits you to heavier bullets on the supersonic side?
I've shot 308 subs from both Bolt/Gas gun with 1:10 and never had a problem with them stabilizing. I've also shot 208 subs out of my 8" 300 with 1:7 twist and they stabilize just fine, I also shoot 125/110 supers from the 8" and they run great.
2. 308 subsonics are less consistent because of the larger casing size?
Never heard this, from what I can tell they're just as consistent as the 300 subs
3. Subsonic 308 can have issues with unburnt powder? (I don't reload, is this just an issue with reloaders or factory subsonic)
Subs have much less powder than supers. If your 308 burns all the powder for the supersonic it will have little trouble burning the powder for the subs. Normally you run into unburnt powder issues in rounds that were designed for longer barrels but people run them in short barreled rifles.
Questions on the 300 blackout.

1. I'm looking into a bolt action because my understanding is they are usually quieter for the shooter vs a gas gun. Is there truth to this or should I look into a AR15 since the 300 BO was built for that platform? Is it a bad decision to go bolt action on a 300 blackout.
Yes bolt guns will always be quieter because sometimes the action of the AR15 is louder than the actual round being fired when shooting subs. If you're going for quiet get the bolt gun, if you ever plan on SBR'ing the rifle go with a AR15. If you never plan on getting a shorter barrel than a 16-24 inches go 308!!!

Current thoughts, I like the idea of having a 308 over a 300 blackout because 308 offers more in a supersonic situation, However, I have other firearms that would make up the difference if need be.
I'm guessing since you're going bolt action you have no plans to SBR it. The 300 was built to be short barreled and suppressed. Again if you have a 16-24" barrel go 308 everytime. I can tell you, the novelty of subsonics wears off really quick.

Here's some info I put together about subs

https://dallasreloads.com/2018/06/26/what-is-subsonic-ammunition-and-shooting-with-suppressor/

Thanks for the info chad.

KRoyal- Thank you for your response. Quite a few of those questions about the 308 was info I ran across while searching over on the silencer forums. But if its really a non issue then I feel like I am leaning towards a 308 over the 300 blackout.

If you are only going to shoot factory ammo, 308 subsonic is tougher to find and more expensive. I have a ruger american in 300 blk and a savage hog hunter in 308. Rarely shoot subs thru the 308 anymore. If you want a super quiet gun for plinking and such, and super sonic hunting under 250, blackout is great. If you can only have one gun and want it to do the most, get the 308.

This. Unless you're pretty sensitive to recoil, in that case get the 300.

One important question to ask: what ranges are you hunting at?

The 300blk would be a better choice if you're hunting at moderate ranges and really want to shoot subs a lot. It's not a 308, but it'll get the job done just fine with the right supersonic ammo. More efficient than 308 when used subsonic. Cheaper ammo, fits in a mini action.

With that being said, I agree with some of the statements above. The novelty of shooting subsonic wears of VERY quickly, as it has very little practical use. A bolt action in 300blk is a niche gun, shoudln't be one of the first ones you get. More like 4th or 5th. Having a can is nice; a full house supersonic 308 is very close to hearing safe out of a bolt action rifle, and there's a lot of stuff you can do with that. My vote: get a good solid bolt action 308, hang a can on it, tell all your hunting buddies to leave the earplugs at home, and go kill some stuff.

So rifles I currently have are

Remington 700 in 6.5 Creedmoor which gives me range, Burris xtr II 5-25
Marlin 30-30 which works as a great little woods gun, Redfield 3-9
AR-15 5.56 is mostly plinking, fitted with a red dot

I guess I don't have an over the top need for either rifle, 308 or 300BO, just a cheap gun to use with my incoming suppressor.

If novelty does wear off quickly of shooting subsonic then it would seem that's another vote in the 308 category.

If you already have a 6.5 Creed and you're about to get your suppressor I'd buy/build a 300blk pistol. Get a good pistol brace and you'll be good to go. I love my 8" 300blk it is so handy for home defense or hunting. Even with a 8" can hanging off the end its still right at or or even shorter than a regular 16" AR15.

Here is mine, it is an SBR not a pistol, but pretty much the same thing with todays pistol braces. 300BLK will put a hurting on some hogs.

Well... I do have a couple of extra lowers laying around... wasn't quite sure how the 2016 election was going to turn out.

Should I go ahead and fill out some paperwork for SBR and do a brace until the paperwork comes back?

If you want to do an SBR you won't be disappointed. That is up to you, but with the pistol braces of today its a toss up. I have a new side folder brace on my Scorpion EVO and it works great. If I were to do an AR pistol I'd get the SB Tactical SBA3, it comes on a 6 carbine tube and is adjustable. Not sure how they're even legal, but I'm sure SB Tactical did their due diligence before releasing them. Looks and functions pretty much exactly the same as the MFT Minimalist stock which is my favorite stock.

given what you have already and the extra lower laying around, you would definitely enjoy a 300blk SBR with an 8" barrel. SBR'ing your lower is really easy.