You will need one of the JP Enterprises MK III Modular Handguard models for DPMS in whatever length you want.
Yes, there are accessory rails available. Here are a few options:
https://www.opticsplanet.com/jp-rifles-tactical-rail-kit-accessories.html
The JP Enterprises MK III Modular Handguard features a 1.75" internal diameter.
The JP Enterprises MK III Modular Handguard will not clear most piston operating systems.
The JP Enterprises MK III Modular Handguard, Rapid Configuration will most likely not work on an Airsoft gun. The JP Enterprises MK III Modular Handguard, Rapid Configuration works with Mil-Spec AR15's and DPMS pattern AR10s.
The JP Enterprises MK III Modular Handguard does not have MLOK compatible mounting slots. JP Enterprises offers picatinny rail segments that will screw into their JP Enterprises MK III Modular Handguards in order to mount accessories.
The JP Enterprises MK III Modular Handguards require the use of the included tensioning tool and a 1-3/8" wrench for installation.
Yes, the JP Enterprises MK III Modular Handguard, Rapid Configuration will work. Just make sure to select the DPMS LR-308 model.
Yes, these JP Enterprises MK III Modular Handguards will work with a Bear Creek Armory Upper receiver.
Yes. The JP Enterprises MK III Modular Handguard will work and can be found in a 12.5 inch, 15.5 inch, and 17.25 in configuration for the AR10 platform.