There is the PreciHole aperture imported by Air Arse .. Ninety squids or at least they were.
In good light with a clear round target a peep-sight matches a scope. The captain of our shooting team at university could shoot sub MOA at 100 yards with a .22 rimfire Anshutz using the match sights on that rifle, a club rifle mark you.
You can order a Williams from Airguns of Arizona, just phone them at the right time and give them your credit card deets. I'm sure they could do with a sale. Easier than paying £150 for a secondhand one in the UK.
https://www.airgunsofarizona.com/sig...e-sight/#tab-2