SIMI VALLEY, Calif. — The U.S. Army needs to “get religion” on 3D printing, especially for parts that require constant replacement, service secretary Ryan McCarthy said Saturday.

Speaking to reporters at the Reagan National Defense Forum, McCarthy acknowledged that industry may be unenthusiastic about the Army taking on 3D printing for small replacement parts, given the lucrative business model associated with it. But ultimately, he said, it has to happen both to increase Army capability and to reduce costs.

“What really kills us is parts. Parts: It’s why weapon systems have challenging operational readiness rates, it’s why weapon systems continue to get heavier over time as you incrementally upgrade the system,” McCarthy said.

The idea of 3D parts being printed in the field has long been viewed as a potential game changer for the military. Parts make with 3D printers tend to be lighter than their traditional counterparts, which can provide greater range for the fuel in a vehicle, or create space for more ammunition; while lighter, new production designs can create parts that are actually more durable than their traditional counterparts.

But for years the military was stalled out over concerns that the parts would not be as reliable as those traditionally produced pieces. “If you have 3D parts in [a Boeing] 737 flying over my office in the Pentagon, why can’t we put it on an armored vehicle?” McCarthy asked. But while the Pentagon continues to lag behind the commercial sector in that regard, there is a growing willingness among leaders to incorporate the capability.

Cost is another benefit McCarthy is eyeing, which is where industry may push back.