Originally Posted by
Jay Andrew
There’s a few thing to keep in mind when dealing with COAL.
If you seat the bullet right on the lands, you may spike chamber pressure. So be careful there.
Every bullet is a little different in its preference, and a lot of it is dependent on Ogive design and chamber design. Some chambers have a really long throat making it near impossible to place the bullet on the lands, others have virtually no throat at all and even loading to SAAMI spec the round won’t chamber with specific bullet types.
SAAMI spec is set by the manufacturer that sponsors the round. They may set the COAL to a specific length so it works in the actions of rifle they intent to chamber the rifle for. Typically the magazine will be your limiting factor in how long you can seat the bullet out.
Seating the bullet closer to the lands in theory reduces bullet jump, which may help to ensure the bullet axis and the chamber axis stay aligned. If the bullet gets “cocked” even by a small amount it will self correct as it exits the barrel but this correction can introduce inaccuracy.
Oddly enough monolithic bullets do better when seated away from the lands. They typically recommend starting at least .050 thou off.
There’s a lot of room for experimentation here, and everyone’s rifle/bullet and cartridge combination will yield different results. Just be careful when “jamming” things into the lands, and back the load off a little, look for pressure signs, before working the load back up again.
Reloading...it’s like knitting for men.