When the Army held the now suspended Individual Carbine trials a few years back, contractors had trouble acquiring the then new 5.56mm M855A1 Enhanced Performance Rounds for their in-house testing. The Army assisted those companies in procuring the ammunition which is still not in wide circulation, particularly for the commercial market.
Now that the Army is looking for an Interim Service Combat Rifle which fires the larger 7.62mm version of the Enhanced Performance Round, M80A1, potential vendors are in a similar situation. The Army has responded by issuing Attachment 0005, Flow Chart for EPR Commercial Sales to the solicitation on FedBizOpps. According to the program, the recommended path is to first contact the Olin-Winchester point of contact (POC) listed on Attachment 0005.
Of additional note, offerors may submit rifles with Mil Std- 1913 or M-LOK rails, with no length requirement. Additionally, as the solicitation does not specify much of anything aside from caliber and full auto capability, if an offeror submits more than one barrel length, they must submit full rifles. They cannot just submit additional upper receivers.