This Vihtavuori rifle powder was originally developed for .50 BMG and for military use, and even the name 20N29 originates from the Finnish Army standards.
20N29 is a single-based, surface treated powder with grain dimensions of 2.3 mm length and 1.3 mm diameter. The burning rate is slower and grain size larger than those of the N100 series powders. 20N29 is primarily used in large caliber and magnum applications with heavy bullets and in long-range target shooting. It is ideally suited for the .50 BMG, but has also gained a good reputation when used eg. in 338 Lapua Magnum and .30-378 Weatherby Magnum.
Sinclair, Issue:5B, Page:094