Plasma Carronade tech appears to contain as least one bug with the RP cost of the final research level (it costs 12m RP instead of what I imagine was intended as 1200k RP) and I'll drop it here in bugs because it changes gameplay rather than just readability. There are two other potential errors worth mentioning just in case they require correction but at least one of them may be better suited in the typos thread.
The final five tech levels and costs for v2.5.1 are as follows:
"50cm" at 125,000 RP
"60cm" at 250,000 RP
"70cm" at 300,000 RP
"80cm" at 600,000 RP
"100 cm" at 12,000,000 RP
I presume 12,000,000 RP for the final level is an error from an intended cost of 1,200,000 RP.
For what it's worth, the step up from 60cm to 70cm only increases in cost from 250k to 300k; I would have guessed that this step would have gone from 250k to 500k, leading to costs of 1m for 80cm and 2m for 100cm, but the lower costs may be by design. Additionally, the final tech level is named "100 cm" with a space rather than "100cm" without a space to keep with convention.
SJW: Fixed for v2.6.0