Home / Proof Marks / British proof — crown over R, and the R/M and DA marks

British proof — crown over R, and the R/M and DA marks

British proof marks · R from 1925; RM and DA from 1988.
What it looks like
A crown with R beneath it; later, RM or DA followed by the last two digits of a year.
Where it is on the gun
Barrel flats.
Date range
R from 1925; RM and DA from 1988.

What it tells you

What this mark authorises you to say

R means reproof — the gun was submitted again, and the mark records a second life. RM marks a magazine shotgun whose magazine capacity was restricted; DA marks a deactivated gun. On the RM and DA forms the year of the change is stamped in the mark, which gives you a hard date for the alteration.

What it does not tell you

What this mark does NOT say

A reproof mark does not supersede the original: both stay on the gun and the original date remains the date of manufacture. And a DA mark means the gun has been permanently disabled, which is a legal status in the UK, not a condition note.

Sources for this page

Every claim above is attributed. The class of source is shown with each one, because a national proof house and an anonymous forum table are not the same evidence — and on proof marks the difference matters.

Reading marks to identify and date a gun

Proof marks name the test and the era. The serial number, where a maker published a browsable chart, can name the year. The lookup cites the threshold behind every result.

Open the serial number lookup

Other british proof marks

Mark descriptions observed and verified 2026-10-14. Proof marks are stamped by hand on guns up to a century old; a photographed stamp and a description in a book are not the same evidence. If a mark on your gun does not match anything here, that is a real answer — see the notes on unidentified marks.