The Junior A Team and myself spent a few days at the Anshutz Factory in Ulm after the World Juniors this year. We had our rifles tested at minus 20 degrees Celsius. What we discovered was very interesting and eye opening.
All our rifles (4 of them) shot poor groups in the cold. Two rifles wouldn't even group at all. In fact one rifle put only 3 shots on the paper. Ironically, the rifles that shot the worse were the rifles that were cleaned and taken care of the most. Mathius Raiber, the full-time rifle tech, thought that our cleaning technique was the problem. In general, we need to use oil, brass brushes, and plastic brushes for cleaning and get rid of all solvents. He uses WD40 on the moving bolt parts, but rubs it off very thoroughly. Here are his suggestions for cleaning:
1. Generally the biggest problem is when the temperature gets cold or there is moisture in the air. After training or racing let the rifle sit next to a heater with the bolt and front sight cover open to let the air flow through the barrel (you should always store it like this). Let the rifle warm up to room temperature. (A dry patch could be run through the barrel right away, but not absolutely necessary).
2. After the rifle warms up, apply oil to a brass brush and scrub in a back and forth motion the first 1.5 inches of the chamber several times. Then run the brush through the whole barrel in one direction. Unscrew the brush (don't bring the brush backward through the barrel, only forward), and repeat the process one or two more times.
3. Repeat step 2 with the nylon brush
4. Run dry patches through barrel until clean
5. If you live or are staying in a moist environment, Mathius thought it would be a good idea to run an oil patch through at the end of the process and leave a coat of oil in the barrel during storage. IMPORTANT: If you do this make sure to remove the oil in the barrel by running several dry patches through the barrel before you shoot again!!!
6. Brass and plastic brushes should be replaced every month since they wear out.
We all had our barrels polished by Anshutz, and it took care of the problem. Piotr and I are looking into options here for testing and barrel polishing. This is something we will need to take care of this Spring. Remeber, throw away your solvents and bulk up on brass brushes.