ECM is not a new technology. In the gun world it's a new application. We used it to produce compressor and turbine wheels for aircraft engines at least to the early seventies using Anocut machines. The electrodes were graphite. It worked but the problem with sludge cleanup moved us away to the newer CNC machining processes. It was the heavy metals that were a disposal problem.
To see it in use now is pretty exciting. I hope they produce some great quality barrels. A lot of good reasons to move away from cut and button rifled barrels. I just hope they don't charge more for this barrel since there is less scrap and quicker production times, but we know how that works.
Brad Stair, my old gunsmith, was telling me about a European company using this process years ago and were building a complete rifle. They didn't last long but it's exciting to see this technology gaining momentum and becoming more mainstream