Home Forums Reloading Bullet Casting 405 grain cast bullet keyhole

if the bullets not stabilizing the bullet may not be cast with an alloy thats hard enough,to firmly grip the rifle lands,
try a 95% WW and 5% pure tin alloy
they may be sized under bore diameter , generally youll want a .459 min, , or the rifle twist rate may be too slow too stabilize the projectile.
obviously it helps if you verify what your dealing with.
verify the rifles twist rate is compatible, if possible get a chronograph to verify velocity
never guess deal in known facts
http://www.bergerbullets.com/twist-rate-calculator/

measure the projectile length and diameter after its sized and lubed
gas check bullet designs tend to produce better accuracy
bullets pushed too over about 1900 fps have a greater tendency to strip in the rifling , some bullet designs are inherently a bit less stable
the properly cast 405 grain bullet in a 458 caliber matched to most common twist rates are stable to well past 400 yards

this non-gas check design from NEI has a good track record

as does this similar
gas check design

many guys have good luck with this heavier 475 grain cast gas check bullet
https://www.midwayusa.com/product/4...-diameter-475-grain-round-nose-gas-check