Response directly from BAD:
All of our receivers, and receiver sets are manufactured with direct impingement (DI) gas systems in mind. However, there are some short stroke piston systems available that utilize a piston rod that matches the diameter of a DI gas tube and should be considered safe to use with our receivers without modifications to the upper. We do not recommend using a piston system that requires the gas tube port on the upper receiver be drilled to accommodate the piston.
Thanks for the inquiry.
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