Potatohead said:
You all seat much longer than me. I wonder if I would have better results with longer seating.
Ive mainly loaded at 1.125". My sr9 will take up to 1.16 I do believe.
The longer the round, closer the bullet will be to the start of rifling and will result in less high pressure gas leakage when the primer ignites the powder charge to build chamber pressure sooner.
And in theory, this will produce more consistent chamber pressures that will result in more consistent muzzle velocities/lower SD numbers and greater accuracy. So if your barrel will support longer OAL/COL than 1.125", then longer lengths (say 1.140"-1.150" or longer working lengths that will reliably feed/chamber from the magazine) should produce greater accuracy (but powder charges need to be adjusted for shallower bullet seating depths).
IMO, there's a point where this may not be the case, especially with lighter 115 gr bullet with shorter bullet base. You do want enough bullet base seated inside the case neck to provide sufficient neck tension/resistance for the initial powder burn/chamber pressure build. I think longer 124/125 gr bullet base seated deeper in the case neck may be a contributing factor why 124/125/147 gr bullets may tend to produce greater accuracy than 115 gr bullet, not to mention longer bearing surface may engage the rifling better for rotational stability in flight.
So even for match shooters with barrel/pistol that will accommodate 1.169" OAL, they may use shorter 1.135"-1.150"+ lengths unless they need to load longer to stuff more powder under the bullet.
I think the best thing to do would be to test different lengths to see which lengths produce greater accuracy. You could try 1.135", 1.145" and 1.155" and go from there while increasing powder charge accordingly for longer lengths. I load for multiple pistols and all of my rounds must feed/chamber in any pistol that may show up when my family/friends/neighbors/coworkers join me to the range. So far for 9mm, 1.135" has worked well for FMJ/RN nose profile. YMMV depending on the pistol/barrel.