cast bullet size for rifles?

S

Shadow9mm

New member
So for revolvers I understand you want to be right at or .001 over throat diameter to get a good seal and prevent gas cutting.

And in general for cast bullets you want to be .001 over the bore diameter to ensure a good seal.

I have a Henry 44mag/spl rifle. Henry stated the groove diameter was .430, and I just slugged it, and it came out to exactly .430.

My sizer is a .430. However the pressures I have been shooting are low, in the 13k to 14k PSI range. I am powder coating and then sizing.

However I have been having troubles with bullets going into the target yawing at 25yds and sideways at 50yds.

my alloy is around 13bhn, recycled bullets that were sized wrong.

I am wondering if my pressures were too low to cause the bullet to obturate into the grooves to seal properly.

my friends loads with the same bullets shoot great, but he is in the 17k to 20k pressure range. and I am wondering if the extra pressure is making them widen out and seal properly.

but back to my main question. I need to buy a new bullet sizer. do I go .431, or .432? or buy both and as the years progress and the bore wears I can go up to .432 later

and do you think going up .001 will solve my instability problems, or is there something else at work?

and before anyone says something, I am asking on cast boolits as well
 
Jim Watson said:
What is your as-cast?
Will it chamber freely?
Click to expand...
I have 3 molds, 2 lee, and a friends noe. The lees drop at .431. The noe drops at .434.

I am also powde coating. Considering sizing to .430 then coating. But i gotta do some testing and see how much it adds.

I can get a .431 and or .432 sizer from lee and would prefer to size after coating.
 
The rule of thumb equation 1422 x bhn = psi. Your bullet alloy could be too hard for your pressure. BHN of 10 is probably better.

Your rifle has groove diameter of 0.430". Your sizer is diameter is a bit too small. At least I would coat after sizing.

I may be stating the obvious. A micrometer is needed for measuring bullet diameter. A caliper is not good enough.

-TL




Sent from my SM-N960U using Tapatalk
 
tangolima said:
The rule of thumb equation 1422 x bhn = psi. Your bullet alloy could be too hard for your pressure. BHN of 10 is probably better.

Your rifle has groove diameter of 0.430". Your sizer is diameter is a bit too small. At least I would coat after sizing.

I may be stating the obvious. A micrometer is needed for measuring bullet diameter. A caliper is not good enough.

-TL




Sent from my SM-N960U using Tapatalk
Click to expand...
One works with what one has. And i just so happen to have aroud 80lb of mis-sized bullets from a maker that i dont know the alloy on, and just have the makers approximate bhn.

I do plan to get micrometers eventually. But they are not cheap, and they are something i need very rarely. Can only think of 2 or 3 times over the past 15yrs where i wish i had a pair. They are on my list, but pretty far down.

I measured my sized bullets at .430 and my hornady xtp at .430 as well as sort of a calibration before checking my slugged bullet. Best i can do for now.
 
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Shadow9mm said:
One works with what one has. And i just so happen to have aroud 80lb of mis-sized bullets from a maker that i dont know the alloy on, and just have the makers approximate bhn.



I do plan to get micrometers eventually. But they are not cheap, and they are something i need very rarely. Can only think of 2 or 3 times over the past 15yrs where i wish i had a pair. They are on my list, but pretty far down.



I measured my sized bullets at .430 and my hornady xtp at .430 as well as sort of a calibration before checking my slugged bullet. Best i can do for now.
Click to expand...
Micrometer is not that expensive. Mine is an used starret bought on eBay for $30. It is essential tool for shooting cast bullets. You need to try to have +/-0.001" with caliper, while a micrometer can easily do +/-0.0002".

I'm known for being cheap and I understand what you mean. But improvision requires flexibility. Perhaps increase pressure to make it work first, then gradually dialing back the pressure?

-TL

Sent from my SM-N960U using Tapatalk
 
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tangolima said:
Micrometer is not that expensive. Mine is an used starret bought on eBay for $30. It is essential tool for shooting cast bullets. You need to try to have +/-0.001" with caliper, while a micrometer can easily do +/-0.0002".

I'm known for being cheap and I understand what you mean. But improvision requires flexibility. Perhaps increase pressure to make it work first, then gradually dialing back the pressure?

-TL

Sent from my SM-N960U using Tapatalk
Click to expand...
got one on order, good reviews, $21 on amazon. will see how she does.
 
Those of us who were members of The Cast Lead Bullet Association and got their magazine years ago, learned that bullet nose fit to bore was the key to accuracy in cast lead rifle bullets, rather than what size the body of the bullet was sized to.
 
For a "cheap" micrometer, check pawn shops and places that deal with old tools. Old, and dingy does not mean unserviceable, if it returns to zero. What it does mean is that they're usually sold cheap.

Do be aware that there is a right, and a wrong way to use one.
 
So i got my micrometer in. Slugged bullet is measuring .4312 . Crud. I have sizers on order for .431 and .432. Will coat, measure, and size. See what i can get them up to.

Also got loads put together at 20k psi with the under sized bullets. Will see if the pressure at least makes them shoot straight.
 
Thats my plan. Ordered some noe expander plugs as well to make sure my cases dont squish the bullet too much while seating.

Still curious though, if the 6k psi difference is enough to bump the bullets up and get them to seal. Thats my best guess to why my friends loads with the same bullet work and mine dont.
 
Mehavey,

Wouldn't the correct adjective be 'problammo'?:D


Shadow9mm,

If you look at Lee's Modern Reloading, 2nd Ed. on this issue, you find that regressing his numbers gives:

psi = BHN ×1280 - 14

That's the pressure at which you start to see deformation. So:

BHN 13 × 1280 -14 = 16,626 psi is the upset pressure threshold.
 
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