Shipping & Returns

Returns Policy

  1. Customers must Contact Us to acquire Return Authorization Number. If an item is returned without prior authorization it will not be accepted and will be returned to the customer. We do not accept responsibility for lost or stolen packages. Please Contact Us for the return shipping address.
  2. If the item received is not the item ordered, it may be exhanged for the correct product at no expense to the customer.
  3. If the item received is defective, it may be exchanged at no expense to the customer.
  4. Products not meeting the above criteria may be returned as new and unopened at the customer’s expense within 30 days of the original purchase with a 25% restocking fee.
  5. Products or orders that are cancelled prior to shipment for any reason may be cancelled with a 15% restocking fee.

Universal Compatibility Guarantee

If you find that a Modulus Arms jig is incompatible with your metal 80% AR-15/AR-308 lower, please send both the Modulus Arms Jig and the incompatible lower back to Modulus Arms. Modulus Arms will modify your jig to fit to your lower, and return everything to you at Modulus Arms' expense. If the jig cannot be modified to fit your metal lower, Modulus Arms will return your lower at Modulus Arms' expense, along with a full cash refund. This guarantee applies on three conditions:

  1. The Modulus Arm Jig shows no signs of use.
  2. The received billet or forged lower must have been deemed by the ATF as a non-firearm, and be unaltered from that form in any way.
  3. The unaltered lower must be compatible with standard AR-15 or AR-308 upper receivers.

If all three above conditions are not met, the Modulus Arms Jig and lower will be returned at the owner's expense. Modulus Arms will immediately dispose of any lower receivers that Modulus Arms, in its sole discretion, deems to have been altered from its original form.

If you need to return an item under the Universal Compatibility Guarantee, simply email Be sure to include your original order number and a brief synopsis of the incompatibility issues you encountered. We will respond with instructions on how to proceed.


Modulus Arms ships most items via USPS Priority Mail. Customers should expect to receive shipment notification and/or tracking information within 1-3 business days of the original order date for in-stock products. We do not ship internationally without exception. Modulus Arms does not take responsibility for lost or stolen packages.

See below for approximate transit times for packages shipped by us via USPS Priority Mail.