I never noticed a problem between heavy and light in my Mosins as far as the bolt, and I have over twenty of them. I DID notice a hard bolt opening on some steel case but the was either dirty chambers, very hot receiver from rapid fire. You may have a bolt or head space problem. The only difference between light and heavy is, the heavy takes a little longer to get down to barrel, so just a little more TIME of pressure is behind it, but any MORE pressure. Were you shooting steel cased or brass cased? I shoot brass cased HB and the bolt is smooth as butter, no matter which rifle I shoot it in. Steel case, that my be a little stiff sometimes even with a clean chamber but never hard enough I need to beat it open.