Paramount was the mid-life iteration of the British 1970 SWING single-shot 4-lug action 'Target' rifle design (Fullbore in the US) that became Paramount in the 90s, then RPA this century, both for product and company names, the current company being 'RPA International'.
Today's RPA single-shot rifle is a direct descendant of the 1970 SWING SN-71 design changed step by step over the years in detail, but still recognisably of the same family. The corporate side of the trio has been small specialist businesses throughout, dedicated to producing quality products with components machined in-house.
I can't comment on the Paramount sight, but it was likely made in-house to very high standards, and the later 'Trakker' is a copy or minor development from it. There are people on specialist Fullbore shooting type forums such as this:
http://www.usrifleteams.com/lrforum/
who will know. The one certain thing, is that it is a well designed and manufactured device made to very small tolerances. The only issue might be wear and tear since it has to date from the 1990s by bearing the 'Paramount' name. SWING/Paramount/RPA manufactured stuff is bomb-proof and rifles dating from the 70s are still in widespread use in the UK and British Commonwealth in 'Target Rifle' sling shooting, 'Match Rifle', and F-Class / F/TR. I have a scope-fitted Paramount rifle that I bought without its original iron sights and as I know its history, know it it has fired thousands upon thousands of 7.62/308 rounds through several barrels. The original components (stock, trigger, and action) are quite unworn and work perfectly. The Gehmann aperture sight-assembly on your sight is of course a more recent after-market addition, and another expensive bit of quality kit.
