You know, bullet that is evenly coated without bald spots.
Wow, what kind of coating?
And what load?
Thank you, now that you said no bald spots. I get it!!!
Haven't really had the time this year to get out and do more testing. Ordered a custom shilen bbl for a 308w puma rifle. It's a 30" 1 in 14 twist with a match chamber. Wanted it for the 155gr bullets & the extra bbl length ='s more velocity/carries supersonic further/wider range of loads that stay supersonic longer. Anyway a side bonus of the long bbl/slow twist is that it holds it's own with cast/coated bullets.
Interesting experiment:
One on the issues with cast bullets/high velocity is the design of the bullet itself. These are old school cast bullets with the long pointed nose and a "wiper" groove at the bullet's body/nose intersection. As the long bodied bullets is fired the nose enters the throat/riflings and starts to twist. The back of the bullet is still being pushed forward in the case mouth/ball throat. That wiper groove is the weak spot at that point due to rotational torque. Too much short start pressure and bad things happen. The long bullet nose will also slump with high pressure/high velocity.The test bullets cast from a cramer 2 cavity mold, 1 standard sp bullet/1 hp bullet.
Didn't matter what load I tested anything over 2000fps the hp bullet was always more accurate, no nose slump. I tested 8 or 9 different powders with those bullets. RL-19 a slow powder with a soft push/low short start pressure got me into the 2400fps+ range with the weakened bullet design (wiper groove). Anything over 2500fps and those bullets would fail.
The lee 312-160tl-2r bullet. No wiper groove & a short nose that resist slumping.
While 10-shot 1 1/2" groups @ 100yds are nothing to right home about. It's a place to start. Those bullets pictured above coated with "smokes pc" john deere green powder coat. Dry powder coating is a type of polyester. The Hi-teck coating is a type of polyurethane. I use the dry powder/poleyester bases pc.
Same bullet but using traditional lubes, note it's 50fps slower than it's pc'd counterpart.
Same lee pc'd bullet doing +/- 2000fps 10-shot @ 100yds moa accuracy.
I can't say enough good about the polyester bases pc'd bullets.