In 2009 I secured a small (approximately 19 mm diameter flan) base metal coin of Carausius with a left facing helmeted bust (wave decoration but without radiate crown) on the obverse with a legend that may be reconstructed as VIRT CARAVSI AV, I think, and a reverse that combined a PAX AVG legend, so prevalent on the coinage, with a device of Virtus or Mars, resting on a shield holding a vertical spear.
Examining the British Museum collection I noted an obverse and reverse die duplicate specimen, acquired in 2016 (acquisition umber 2016,4042.1) and found at Pleshey, Essex. The online description postulates an official product of the unmarked mint.
Also the notes to the coin online observe that the portrait style is similar to the gold aureus found at Ashbourne in 2007 (acquisition number 2009,4112.1) .
My own opinion is that, whilst there is a very broad similarity to the gold coin, and the reverse style is good, the two pieces under discussion here exhibit some differences in style and the obverse bust style is much more crude. These two base metal coins may, in all probability, be irregular issues struck at an unofficial mint.