So I am new to the AR pistol market.  I will probably be building my project around August (I have a few other firearms purchases to make prior to this one).  I know I don't want to go below10.5" as I really don't like shorter variants (when I have shot buddy's pistols).  I've heard that with an 11.5" barrel you can still maintain decent velocity and accuracy relative to sub 10" configurations.  I've also heard that there are less issues regarding the buffer weight and such, and that they are more reliable when shooting different ammo on the market.  Is there going to be a big difference between an 11.5 and 10.5 inch barrel (both will be 1:7 CHB)?

Also, I've been told the holes at the gas block need to be slightly larger than that of a 14.5" or longer barrel.  Is this true?

I want to thank everyone for their input on my questions and I apologize for my ignorance on this topic.

Hard Shell,

Thanks for the response.  I am uncertain as of yet if I plan on running this pistol suppressed.  Do you know if a 10.5" gun can be run successfully with a suppressor?

i love the 10.5" length. functions fine with the spikes buffer setup. no flash with a phantom hider as well. go govt profile, its so quick & handy!

if i were to do longer it would only be for a retro look XM or commando. otherwise its 16" or 10.5" all the way :)