Most practical AR round to supress that's not niche, or limp-dick.

[EotS]

I'm wanting a canned AR because.

Actually, something cool for night stuff. Varmint and predator control. Say, 250yds and under.
What's the ideal round and bbl length without getting too deep in the weeds? I have a number of 556 guns, and a 16in 300bo upper that I honestly don't remember the origin. Build up the 300, use one of the 556s or something else?

 

[Cascade Hemi]

50BMG

 

[Gasgun]

For out to 250, use one of your 5.56 guns.

 

[Jsp556]

50BMG

 

[7mm-08 Freak]

If its subsonic its limp dick. I just use .223 and a can

 

[diggler1833]

6ARC / 6.5 Grendel / 6.8 SPC

All will do what you list as a requirement, and do it well out of shorter barrels. I'd probably lean towards the 6 ARC since you didn't list anything bigger than predators.

 

[nikonNUT]

AR-15, 16" barrel, .223 Hornady Varmint Express. Done and dusted!

 

[7mm-08 Freak]

AR, 16", .223 Hornady Varmint Express. Done and dusted!

That Varmint Express shiz the nit! My short AR 223 Wylde loves that stuff.

 

[the monk]

300 blk

 

[W54/XM-388]

That .338 ARC might work well for you if you are wanting the small frame AR platform rounds.

 

[MO Fugga]

.458 SOCOM. Break shit. Quietly.

 

[nikonNUT]

That .338 ARC might work well for you if you are wanting the small frame AR platform rounds.

You shush! I'm TRYING not to buy an upper!

 

[reelserious]

6.8 spc is what fits your needs. 1800 ftlbs energy in a 7lbs package

 

[st1650]

450BM with the 395 SubX ...
Or the 338 ARC

 

[Romeo458]

350 legend. We've loaded all kinds of 9mm (355) and resized 385 pistol bullets. It smacks the hell out of deer and drops them better than the 45-70 shooters I hunt with. Not much correction needed to 200 yards. The primary arms 7 62x39/300aacbalistic drop ive shot to 400yd with 150g loads accuratly. It's also got some nice suppressed rounds out.

I'm a 350 fan boy

 

[LRRPF52]

How long would you like to keep the suppressed overall length limited to?

 

[Jsp556]

6.5 Grendel is a safe bet. I haven’t ran across a 6.5 Grendel barrel that wouldn’t shoot one of the Hornady offerings 1.5moa or under.

14.99 per box AAC ammo has worked well this year killing pigs and up to 200lb white tails. It shoots pretty good 100 yard groups in 2 of our guns but sd’s are too high to consider it for any long range shooting.

6mm ARC would be my second choice.

Both are fun to shoot and easy to maintain sight picture for fast follow ups with a thermal. Both are point and shoot flat out to 200 yards. Both kill critters better than 556. Both suppress well using 308 cans.

I’ve got 5 Grendels and have 2 6mm ARCs. Both rounds get everything you can get out of the small frame platform.