It has been a funny old Imperial, with some one day of good shooting at the start and a lot of mediocre groups and scores; however I'm hoping that on the final day I can work out definitively what the problem is and sort it before the trip up to Glasgow. My position seems OK in itself, my sighting is fine and my trigger release is good so it's a bit of a mystery. I'm hoping that the new barrel is at least a contributing factor.
After a bit of a lie in, I shot the 600x Prince of Wales' prize at 09:50 in the morning. It started off OK, but soon became clear that there was a 1.5 minute* group in the offing (I normally group to about a half of this at short range.) Again, the slight pulse beat / wobble was present, which is starting to become pretty conclusive as a common factor.
At this stage, I've eliminated every other variable so whatever remains must be the cause. It looks like the retailored jacket still isn't quite right. I'd got a couple of hours before the National Match, so I grabbed my old Truttmann jacket and headed off to the British Commonwealth Rifle Club to do some SCATT. SCATT is an electronic training aid, which allows shooters to fire their rifles without ammunition and simulates what the shoot could have looked like on the target.
After three ranges of the National Match, I still wasn't 100% sure that I was quite as happy with the old jacket, but everything was much more still even if not quite as comfortable. I decided to give the same setup a go in St. George's II and managed a much better 3/4 moa group in a tricky wind with a bracket of 2 right to 3 left. I qualified for the final with an aggregate score of 149.19 ex 150.30, or would have, had I not been departing for Dundee at 06:00 the following morning.
Well, it's not exactly been the lead up the games that I'd hope for, but I reckon I've got to the bottom of the group issues. Roll on Glasgow.
*Note for non-shooters: Group sizes are generally quoted in minutes of arc. One minute of arc is a sixtieth of a degree and equates to 1.047 inches per hundred yards of distance between the shooter and the target, so a 1.5 minute group is about 9 inches across. While the bullseye is about 12 inches at 600 yards, any wind changes at all or errors in group centring make it very, very easy to lose several points with only a 3 inch margin of error at a third of a mile.