Load Guidelines for GS Custom SP Bullets
Due to the drive band design of GS Custom SP, HV and FN bullets, bullet engraving pressure is significantly reduced. This simply means that less pressure is required to move the bullet from the case, through the leade (throat) and into the bore. The bullet therefore creates expanding volume faster than smooth or grooved bullets. This requires more or faster powder to sustain the pressure levels required to accelerate the bullet. This is also why higher speeds can be achieved with drive band bullets compared to smooth or grooved bullets.
The advantage of the reduction in engraving pressure makes load development relatively easy. Any load that is given as a safe maximum, for similar weight conventional jacketed bullets, will be safe as a start load with GSC SP, HV and FN bullets.
Here are guidelines that we have found useful in load development with GSC bullets:
Separate speed and accuracy development. Develop the desired speed first. This will require very few bullets as only one shot needs to be fired at each charge weight to determine speed. (We assume your chronograph is reliable and reads every shot.)
Once speed has been established, tune for grouping by changing cartridge overall length.
Always use a magnum primer.
Use a propellant that will leave as little airspace in the case as possible.
Outside neck turn your cases rather than inside neck ream them.
Ensure that case mouths are chamfered.
Do not crimp cases onto the bullet.
Loading a GSC drive band bullet into the rifling will not raise pressure as is usual with conventional bullets.
With the above in mind, follow normal safe loading procedures and, if you have any questions, do not hesitate to contact us.
GS Custom Bullets,situated in Port Elizabeth on the East Coast of South Africa, manufactures solid copper, turned, monolithic bullets for hunting and sport shooting. These bullets are used by hunters on several continents, hunting from the smallest of antelope to the largest of dangerous game, using the smooth HP bullet, as well as the more popular HV, FN and SP bullets with the patented drive band concept. GSC bullets are configured for the highest possible ballistic coefficients. SP bullets are mainly used for sport shooting. All GS Custom Bullets are moly coated.