In the last article we established that the average factory rifle produces around a 32mm group out of the box and when modified, this figure will shrink to the tune of 28mm or 1 Minute of Angle at 100 yards. Both are eminently usable for putting meat on the table within a couple of hundred metres, but some of us shoot in open country where the shots are a little further and we require the accuracy potential that will increase our hit percentages at these ranges.
Enter the semi-custom rifle, a firearm that has had one of its major four components (barrel, trigger, stock or action) changed with an aftermarket option or blueprinted. Action ‘blueprinting’ or truing involves a gunsmith machining the barrel threads, action and bolt surfaces to ensure the bullet is entering the bore as straight as possible. To do this the bolt must be centred to the centreline of the action, which is square against the shoulder of the barrel threads.