Your Browser is OutdatedQ&A for Pantheon Arms Dolos AR-15 Lock Collar — 4 Questions & 5 Answers
Yes, with a caveat. Since there isn't a gas block or tube to retain the lock collar, Pantheon recommends using their Barrel Stop-Pistol Caliber specifically for blowback builds to provide an index point and limit the collar movement when it's not attached to your upper. You can find that here: https://www.opticsplanet.com/pantheon-arms-barrel-stop-for-dolos-equipped-ar-15.html. However, you 9mm barre also has to have a long enough mounting area to work with it (for example my Faxon 9mm barrel does not, so it will not work with the barrel stop).
Yes, this has the three holes, we just haven't received an updated image from Pantheon Arms yet. I apologize for the confusion.
It depends on what handguard it is. Pantheon has a complete list of compatible handguards under their support section, which can be found here:
https://pantheonarms.com/pages/support
No, Pantheon states they found that the height of the gas block with many piston systems does not allow enough clearance for a handguard to be installed.