In the May 2005 issue of Rifle, Nosler tested a standard SAAMI spec 300 WSM and a second barrel chambered with the same reamer except for a straight 0.250 inch leade. The thought was to determine if seating bullets out to 2.880”, 2.90” and 3.0” and the corresponding additional powder capacity would allow additional velocity gains without overpressure. They used an Oheler Model 83 (I thought they only made a 43?) for all pressure and ballistic measurments. They matched SAMMI pressures (factory loads) using H-48310sc(69 gr), and RL-22(70.5 gr) at the SAAMI OAL of 2.82 inches (59,000-60,000 psi). They then increased the bullet OAL to 2.880”, 2.90” and 3.0” using the same loads as above. What they found was that even though the load remained the same, the pressure increased above SAAMI spec levels as the bullet was seated to 2.880”, 2.90” and 3.0”. This was true even though the it (bullet) was not touching the lands yet (maybe it touched at 3.0”). They also mentioned that they did not believe that using a slower powder would help I am just getting into the reloading game and I don’t know enough of the variables to know if what they are saying is true. I am sure the top gunsmiths like Chris, Kirby, etc. must have some knowledge of this since they are deciding how much leade to provide, OAL, setoff from the lands, etc. I am sure this topic must be of interest since it seems most on this site are building toys that press the long-range edge. The reason I am asking is I want to build a 6.5mm using a short action 2.92” max OAL length and I would like to see if I can get 3000-3100 fps from a 24” barrel with a 142gr SMK. Am I dreaming or would it be pushing the pressure envelope? I don’t want to be at max pressure when it seems the best accuracy is usually with a combination that is less than max?