Smokey cases around the cartridge neck can be caused by the case either being to hard to expand into the chamber and seal the escape of gases or by undercharging the round causing the same effect.Blu wrote:Charlotte, two things, first the brass. Now the books say a too light powder charge will cause the burn on the outside of the case. And they are right.
However, brass vaires in elsaticity from lot to lot, and between makers. Sometimes cases don't seal completely, even with the "proper" powder charge. Also, since the brass seals, and then "springs back" away from the steel of the chamber, it is possible to get gas residue on the cases, at the mouth, with nothing wrong, at all.
Now, cases loose in the chamber, held off center axis by the extractor, could show a mark down one side. A loose chamber is both a problem, and not a problem, depending on the specifics. In fact, guns intended to operate under the worst possible conditions (military arms) are often cut with slightly oversize chambers, because reliablity is preferable to best accuracy.
Blu
Case expansion into the chamber is generally known as 'Obturation' and when bench loading, it's a good indication that you don't have the formula quite right.
Cheers