That is one thing I looked for and did not find in the article. No mention of barrel length.
It did say that the overall length was 17 inches, so I did guess at an 8 to 10 inch barrel.
I all so looked at the pistol and noted that there was no place for the recoil absorber spring. I thought ouch, that’s gotta hurt!
I was assuming 10”; I know the Kel Tec is 9.2” with a 1:9 twist. Maybe the RR is about the same? It’s pretty accurate (3” groups, slow fire rate) at 100 meters, thanks to the light and fast bullets...