I have been following another thread hear and a question came to mind. This may be irrelevant but it does interest me. We all know that a longer barrel enables the shooter to squeeze every bit from the powder in the cartridge, right. Is it possible to have the barrel to long that one begins to go backwards? That is, can the barrel be so long that the powder/charge no longer helps the projectile or even begins to hinder the performance? If this does occur, at what point and how would one determine it on a specific caliber/charge? In theory there should be no effect, since the gasses are trapped. The pressure is what it is, until released. But, when does the length of the barrel, if at all, become overkill? Of course there is another theory, inaccurate as it may be, it is still theory. If the charge is being completely used and has applied it's maximum effect on the projectile, it would be reasonable to think that the longer the barrel is, past its beneficial length, the more resistance the charge/projectile would have to overcome this hindering the performance. What is reality?