@MZMcBride as binbot says, if the UA data was going to be available to users who aren't CheckUsers it might prevent CUs from using it as it would reveal the useragent (sometimes of a specific user) which might be a privacy policy vio.

@binbot, regarding common UAs, yes, however the collateral from a single UA is much less than blocking the everyone on the range. Just as we do with blocks we're trusting the blocker (in this instance a CU) to assess collateral before making the block.

Only issue with changing block settings is that browsers like Chrome change versions *very* regularly, so it would be ineffective at actually stopping the target user from editing.
Plus it would also probably be necessary to be able to prevent more than one UA from using a range (which is why I thought regex might be useful).

Yes! There does need to be a way of incorporating changing versions though. From DQ's comment this will need to be available to CheckUsers (as the only people who can see useragents). Also the specific UA blocked probably need to be viewable only by CheckUsers so that that personal information isn't released to others.

I was thinking more that rather than blocking everyone (a hardblock) from using an IP or range, there could be an option to prevent a specific useragent (or part of a useragent to account for version changes) from using that IP or range. Therefore it would be regardless of their username but reliant on their IP.

Could possibly be done through regex?