I have owned several Brno Mod. 21 & 22 rifles. I can not remember all the letter designations but H was one of them. I have owned Mannlicher Models which fell into the 22 Model, and 21's with 21.5" barrels and others with 23.5" barrels. The letter "H" and some other letter stood for either the 21.5" or 23.5" barrel. Most of the 21's I owned had the integral dovetails on the ring and bridge. I have owned a few without the integral dovetails. These had a round ring and bridge. I have also owned a couple with the round ring and bridge that had German Claw Mounts milled into the ring and bridge and was told that these were special order rifles and came from the factory so equiped. All of the 21's that I have owned had double set triggers that were adjustable and a butter knife bolt handle. Also everyone I have owned were very well finished and polished with no tooling marks anywhere. The stocks were European Walnut and very slim and well fitted with tight straight grain. IMHO the Brno 21's were the best commercial made rifles I have ever seen on the market for the money.