Does anyone know how fast a 125gr coated 357 Magnum can be pushed
befor it needs a gas check?
Is it due to fps or the amount/kind of powder used ?
Thanks for any info.
Velocity "how fast" is meaningless when it comes to a coated bullet. You simply can't drive them fast enough to affect the coating.
Pressure is everything.
A gas check is just what the name implies. It keeps the hot gases from flame cutting the base and drive bands of the lead bullet. (keeps the gasses in check)
Bullet lube does the same thing. It acts like a gasket sealing the bore along with giving the lead bullet a film layer to ride on against the bore.
Powder coating is just that. A coating (plastic jacket) that acts like the film layer of a lubed lead bullet. It's a layer of plastic that the lead bullet rides on against the bore.
The pressures exerted on the lead/cast bullet are what affects them. Cast rifle bullets that have long bodies are affected the most by the pressures of the loads that are exerted on them.
Cast/coated revolver bullets tend to be short/square bodied bullets. The only thing that really affects them is skidding. Skidding is when the drive bands/sides of the bullet don't hold the lands. The engraving of the lands on the cast/lead bullet will actually widen.
These are 8/9bhn cast bullets that were pc'd (coated) and shot in ac 6" bbl'd 629. It's a pretty hot 44mag load of 11.5gr of unique. The max load is 11.7gr of unique.
8/9bhn cast/pc'd bullets in a 308w. They are a 122gr cast bullet with no gas check installed. A 10-shot group @ 50yds. Had 1 of many senior moments and wrote down 1700fps for that 10-shot string. It was actually 1600fps.
Anyway, it's the pressures and the rotational torque exerted on the cast/lead bullet that affect them. Velocity is a secondary biproduct of a load and comes into play with the rpms of the bullet spinning.
