Gibster, back in my engineering days when I worked in the nuclear power industry 3 full thread engagement was all that was needed to satisfy maximum safety requirements. I feel sometimes today we carry safety a little too far in some cases. I have never seen a breech plug failure in an old or new rifle. I have seen bursted barrels, drums blown out, nipples blown out but no breech plug failures. Not to say it hasn’t happened or that it won’t, I just have never seen it.