AR15 pistol caliber selection help

[NY700]

So I know topics like this tend to spiral but before I pull the trigger I want to make sure there is t an aspect of this build I may be missing

Plan is for an AR15 pistol in a rifle caliber in the 10.5 - 12.5” barrel range.
This pistol will be run I suppressed at least for the next year or two as I currently don’t own a suppressor.

purpose of the firearm is to fill that Home Defense/truck gun niche. Light, portable and maneuverable. With engagement 300yds and in.

Again light weight and simple is key so likely will run with just a red dot maybe something like a 3x acss type reticle with backup irons.


my original plan was for a 5.56 upper. Plenty of ammo selection, light recoiling. Still plenty devastating on soft targets. Ammo surplus for my other rifles so ease of supply chain and I can run cheap practice ammonia my progressive orby bulk.

next thought was 6.8spc. More power, still effective in short barrel. Manageable recoil withlots ofammo options.
im also running a 224valkyrie so I have 6.8 bolts on back up as well as mags.

third option 6.5grendel. Best ballistics with very good energy numbers to 500yards even out of The short barrel. Also Wolff is making very inexpensive yet decent practice ammo at $5 a box of 20.

ok thoughts

 

[The DFC]

Have you considered 300 Blackout for that length of barrel?

 

[hafejd30]

Mine (now a sbr) started as a suppressed 300 blackout 8” barrel. I now have a 10.5” 556 upper for it. Both suppressed. Switch the uppers depending on what I want to shoot that day. Primarily I carry in the 556 configuration as I use my 30 cal suppressor on multiple other platforms

 

[roostercogburn98]

Take into consideration what barrel length your suppressor manufacturer will still warranty their stuff on as well. Yankee Hill used to be 10.5 inches.

 

[powdahound76]

556 gets my vote.
Inexpensive and easy ammo, lots of choices.
Works just fine except on armor. What are any of us shooting that has armor?

maybe. A big maybe you would encounter a bad guy in armor.
In that case, practice head shots too.

 

[N-C]

If only one 223/556

If can have Second one 458 SOCOM

 

[LeadZeke]

For 10.3in+ 5.56 is the right answer, especially for serious use.

Any shorter, that is .300blk territory.

The others are really hunting rounds at this point.

 

[bfoosh006]

IMHO....

11.5" -12.5" 5.56

10.5 and less.. 300BK Supers... FWIW, purpose built Lancer 300BK mags feed the best for me.

I have a "love" for the 6.8.. but ammo can be tough to easily find and "expensive" to stockpile.

 

[Cheyenne Bodie]

12" and over 6.5G, 11-9" 6.8SPC, 9" or less 300AAC. Just my opinion.