Navy Lasers, Railgun, and Gun-Launched Guided Projectile: Background and Issues for Congress [Updated July 7, 2021] [open pdf - 2MB]
From the Introduction: "This report provides background information and issues for Congress on three potential new ship-based self-defense weapons for the Navy--solid state lasers (SSLs), the electromagnetic railgun (EMRG), and the gun-launched guided projectile (GLGP), also known as the hypervelocity projectile (HVP). The Navy's proposed FY2022 budget requests research and development funding for continued work on SSLs, but proposes suspending further work on the EMRG and GLGP programs and requests no research and development funding for them. The issue for Congress is whether to approve, reject, or modify the Navy's acquisition strategies and funding requests for these three potential new weapons. Congress's decisions on this issue could affect future Navy capabilities and funding requirements and the defense industrial base."
CRS Report for Congress, R44175
Congressional Research Service: https://crsreports.congress.gov/