404 Jeffrey - Oh Boy, another project!

[Riflecrank]

I use .461" sized, hardcast bullets in my .458" to .459"-grooved barrels all the time.
Prefer it.
No leading or unusual behavior at all.
Chrono results are similar to what I get with .458"-diameter jacketed and monometal copper and brass,
with same charges.

You are measuring "groove diameter" as .415".
"Bore diameter" is hard to measure unless you have an expensive set of gauge pins graduated in 0.0005" to 0.001" intervals
I would happily use .418" diameter lead bullets in that barrel.
Use .416" diameter jacketed and monometal copper and brass also.

Powder-Coat Paint is recommended on the cast lead bullets. Sizing after PC-Paint works great.
The PC-Paint is like a lube on the bullet, no other lube necessary.

 

[Rez Exelon]

I use .461" sized, hardcast bullets in my .458" to .459"-grooved barrels all the time.
Prefer it.
No leading or unusual behavior at all.
Chrono results are similar to what I get with .458"-diameter jacketed and monometal copper and brass,
with same charges.

You are measuring "groove diameter" as .415".
"Bore diameter" is hard to measure unless you have an expensive set of gauge pins graduated in 0.0005" to 0.001" intervals
I would happily use .418" diameter lead bullets in that barrel.
Use .416" diameter jacketed and monometal copper and brass also.

Powder-Coat Paint is recommended on the cast lead bullets. Sizing after PC-Paint works great.
The PC-Paint is like a lube on the bullet, no other lube necessary.

Appreciate the feedback and sharing the experience. I had a feeling you might be one of the ones that would be able to chime in with a bit more experience on the topic. Guess I need to actually get those things ordered to experiment. Considering I've got three in 416 I guess it won't hurt to buy the value pack. If they don't solve my issue here I bet the 416 Rem or 416 Taylor would eat them up since I've got to get back to those projects at some point too.