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March 10, 2014
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Ok guys I need a little help. I have a 445 super mag accuracy was poor with jacketed bullets so I thought I would try some cast. Just ordered a box of cast performance 300gr gas checked hard cast wide meplat bullets sized to .430. Before they came in I slugged and measured my barrel and chamber throats they measured in around .426. I received the Cast bullets loaded them to 1grain under max for a jacketed bullet, accuracy was decent with 3 inch groups at 50 yards. So, my question is what would be the optimal size cast bullet for my bore and throats.
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Dans Club
February 22, 2009
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General answer- .428-.432 if your chambers are in fact .426". Now, on to the more technical stuff...
How did you measure your bore and throats? The only way to get an accurate measurement is to slug the bore and use pin gauges (or slugs) to measure the chambers. Hopefully you will have larger throats than the bore.
The lead bullet should be squeezed smaller, in its run from start to finish with the chamber larger than the bore. Optimally, the feed cone end of the barrel's bore should be a bit larger than the muzzle end but as long as it isn't larger than the throat; that's adequate.
Regardless of the size of the bullet in the case, the relation of the throat to bore dimension is most important to accuracy, whether the bullet is jacketed or lead. Roogars (sic) are notorious for having a squeeze in the barrel where it meets the frame, thus negatively affecting their accuracy until a smart owner figures it out.
FWIW the throats on all my 445s measure .429(-)" and I size cast bullets to .430". Any size larger than the throat, which can fit in the case, should be fine. To get accurate measurements, be sure to really look at the throats and ensure that there isn't crud (carbon, lead, copper) built up first.
I hope that made sense-
Ron
Technically, the glass is always full; half liquid, half air....
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