From an internet website giving advice to biathlon shooters:
QuoteFor many years, I usedCCI Standard velocity ammunition in my Anshutz 1827B for most of my races and shooting practice. Though many fellow biathletes complained that CCI shot poorly in their rifles, I had experimented with CCI match grade, Federal, Remington, RWS, and several others which elude me at the moment, and quite frankly any difference in the groups I was shooting slightly favored the Standard velocity CCI, and in addition, both the Remington and Federal would occasionally jam my rifle. I attributed the slight difference in grouping to the difference in muzzle velocity, and my poor follow-through. Since CCI Standard velocity was the cheapest ammunition I could find locally, I used it almost exclusively.
Occasionally I would have a Winter Biathlon race where I would have trouble zeroeing the rifle - it would refuse to group, with most of the shots not even hitting the paper. This was usually in Colorado, and since from my window seat on the plane I have seen the luggage handlers literally toss my rifle in a high arc onto the conveyor belt, I just assumed that the rough handling somehow knocked the sight way off. But when I got back to California, the rifle would inevitably shoot just fine. I figured at the time maybe it got jarred hard enough on the trip back to undo whatever was wrong. Yeah, right! This happened several times, but each time it seemed that there was a good reason it wouldn't group - I was late to the range and rushed, or very tired from combining a business trip and a race, or there was a lot of wind. At one point, I was thinking maybe it was the altitude - the Colorado venue is nearly two miles higher than my home range, and two thousand feet higher than Auburn Ski Club (ASC) where I've done most of my winter Biathlons. It wasn't until I went back for Biathlon Nationals at Lake Placid one year that I finally found the root cause.
As before, I couldn't seem to bring my shots onto the paper during zeroeing. But this time I wasn't tired, I wasn't rushed, I wasn't at altitude, and there was no wind. I was complaining at dinner that evening to some of our group about how my rifle sight seemed to be non-functional, when someone at the table behind us (I don't know what his name was, or what club he was affiliated with) turned around and asked me what kind of ammunition I was using. I replied CCI, and proceeded to say that I had run experiments with my rifle, and that the CCI ammunition was just fine - that couldn't be the problem. He then asked me where we were from, and I replied California. He then asked me what temperature we did most of our events at, and I replied 70's for Bay Area events, and 30's to 40's for our winter events at ASC. He then said, "I think I know your problem. I've got some RWS ammunition in the trunk I can give you - try that." Sure enough, the next day, my rifle was shooting the tight groups that I was used to. The fellow told me that the ammunition was packed so that it would burn more consistently at low temperatures. The trade-off - lower muzzle velocity. Bingo! Both the Lake Placid event, and the Colorado events that I had had trouble at, were run at temperatures pretty close to -20 Celsius - quite a bit colder than our California events. Another lesson learned.
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