demented Let me start off by saying I am a MMP shooter... there that tells you I am biased from the start so consider that.
My rifle is a Knight, have no idea if its considered a tight bore but MMP's sometimes are a bear to load even with a squeaky clean bore.
I have several Knight rifles and I shoot the black MMP HPH-12, they load with pressure but nothing undo... Two hands on the rod and 35-4-#'s of pressure and they go right down.
With what you are describing I would bet that you might have some Black MMP HPH-12 sabots. They would definitely require MORE pressure to get down.
Busta's comment is right in line they are a very good sabot (Harvester Crush Rib) although i really do not prefer them. But remember I do not have a rifle that requires them or the MMP counter part the HPH-3p-EZ-Load. I found when I shot the CR I had no problem with acciracy but i did loose velocity. When I ran the same test with the 3p - they shot equally well but did not loose the velocity that the CR's did. But remember the bettersabot for me is the slightly thicker HPH-24.
These are also just my thoughts.... I believe there formulas that they use to conjure up their polymeres for the sabots are different also. It seems to me that the Harvesters operate better in warmer temperatures. They seem to hold their form better. I use the MMP because of the temps that I normally hunt in. In the colder weather the MMP loads better and conforms or sinks into the lands and grooves of the bore better. Hot barrels and hot weather are really tough on MMP's. That is just my observation and thoughts.
