Originally Posted by
Mk VII
I have disassembled these in the past to tighten up the screws underneath the windage knob which are holding the windage yoke on - you need to make a tool to fit the spanner nut in the knob (I turned down two Allen screws to the right size and drilled and tapped a flat piece of steel to hold them at the right spacing). A bit of threadlock on them will stop them coming loose again.
Parker-Hale catalog, 1961: - “ This is a barrel finishing process which we acquired in the year 1922, through the good offices of the late Mr. T. B. Simpson, a Bisley visitor from Australia, where he represented a well-known British firm of pump manufacturers. Mr. Simpson brought over sectioned barrels, one of which had been burnished by passing through sized steel balls under pressure. The difference between the unprocessed barrel and the other was remarkable, especially at a time when riflemen were troubled by the presence of hard metallic fouling which in some instances seriously affected the accuracy of their barrels
“ The sectioned barrels showed that the ball burnished barrel had a dark mirror-like perfectly smooth surface on the lands, whereas the other barrel, although well rifled, had innumerable cross-cuts on the lands which under the great pressure which the bullets exerts on the bore, scrapes off some of the metal jacket of the bullets until an excessively hard lump of metal forms which cuts into the passing bullets and destroys accuracy.
“ Ball Burnishing closes up these cuts on the lands and although it does not touch the grooves it is rarely that any metallic fouling collects there as these grooves are cut longitudinally, i.e. in the same direction as the passage of the bullet, therefore, there are no cross cuts to scrape the bullet skin and, therefore, no hard fouling of any consequence.
“ In a barrel that is worn, the edges of the lands become rounded, thus reducing the area of contact available to the ball in the burnishing process; it follows, therefore, that Ball Burnishing is most effective when applied to unworn barrels. For this reason it is to be recommended chiefly for application to new barrels, thereby improving their initial levelness and the homogeneity of the wearing surface of the lands giving an expectation of greater accuracy, longer life and less likelihood of collecting metallic fouling………
“ Ball Burnishing enlarges the average bore by approximately one half thousandth part of an inch, an almost infinitesimal amount which in no circumstances can cause any detrimental effect.
Many marksmen using Service rifles are misled into error in specifying precise bore sizes when placing orders for new barrels or new rifles. It is impracticable within the tolerances maintained under present day conditions [1961] to furnish barrels with bore sizes which were current before the second World War.
“ New barrels today are officially acceptable when made between .301 and .304 gauge, but 98% of new barrel production is found to gauge between .301 and .3025……….”