Hi Sid, the throat reamer is a mix of both features. I wanted a seperate reamer so that the COAL would suit client rifle magazine lengths. At the moment I am working on a Sako so the COAL is 40 thou shorter than my COAL which suits my M700. Along with this, yes, the reamer has a very shallow leade angle designed for the VLD and Amax style bullets. The downside of this specific angle is that (generally) I am finding it difficult to obtain optimum accuracy with the SST, a bullet I quite enjoy using. These difficulties appear to be the same regardless of cartridge design or caliber. In other words, on a week to week basis, I find that if a barrel has its leade cut to match/target bullet configuration, it can be finicky with certain, stout jacketed hunting bullet designs. The most forgiving sporting bullets tend to be, Speer, the traditional Interlock and the Partition. I am hoping that in time, by experimenting with seating depths (SST), I can learn more.
As for the accuracy, I think I have been very lucky that everything has come together so well, magnum recoil is not usually conducive to sub .5 MOA accuracy. Good barrels, a good cartridge and attention to my own work habits and shooting habits of course. The other important factor was keeping an eye on velocity spreads, keeping the ES down low. The standard primer is definitely my pick in this regard. I actually tried one of my extremely accurate but high ES loads at 600 yards and the group was abysmal, highlighting the importance of a low ES.
I have got some U.S 869 here which I need to test. Not sure if it will be worth it though. I reckon the case will need around 85 grains-87 grains and have no idea of what velocities and accuracy to expect. Just have to try it and see.
Cheers.