Hodgdon H4895 reduced load formula

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Ok guys I am looking at playing with some lead cast bullets for my 375Ruger. Not sure why but I want to try and get a spring bear with and slow lead.
I have been trying to figure out this H4895 reduced load thing https://www.hodgdon.com/PDF/H4895%20Reduced%20Rifle%20Loads.pdf

I am sure its simple. sounds like you take your max charge and X by 60%

example
. 235g TSX max load is 71g of H4895. (Hodgdon site)
71 x 60% or .60 = 42.6grains
Right?

problem is when I check the math against the examples they have on the Hodgdon site they don't add up.

example
125g bullet max load is 53.7g of H4895
53.7 x 60% or .60 = 32.22grains

except on their "examples" on the page about the reduced loads it says 40.5grains

I am just a little confused.
Also will this formula work for lead cast bullets?

any help would be great
 
They show normal loads on the website, so your math for the reduced loads is correct.
You may find the reduced load of H4895 is still to much for cast bullets, perhaps even so for gas checked cast bullets
 
yodave said:
They show normal loads on the website, so your math for the reduced loads is correct.
You may find the reduced load of H4895 is still to much for cast bullets, perhaps even so for gas checked cast bullets
Click to expand...
Then where do they get their numbers in the link I posted. I went and found the loads on their site.
I did the math and they don't match what they have as examples.

I have 264g lymans with gas checks. loads in the lyman manual are 1800-1900fps
How would I tell in the cast it moving to fast?
 
The 60% rule is a general equation they have proven works.
The reduced loads they list in that document are ones they developed in the lab. It could just be that's what they found to be a good load in terms of accuracy in their test rifles.

Since 60% is the starting load and the normal max is the max load, you can load anywhere in between. Since their loads are higher than the 60% load, not lower, that is most likely what they have done. I've found some 60% loads are quite inaccurate and have to bring the loads up quite a bit before I get decent results. Sometimes I'm at 75% loads before I find an accurate load.

You can tell if a cast bullet is moving too fast if you have chunks of lead left in your barrel or the bullets are patterning the size of a barn door at 50yds. I have the Lyman Cast Bullet Handbook and many of their loads are way too fast for any of my rifles with the alloys and lubes I use. Maybe I could get better results with heat treating or higher velocity rated lubes but what I have is good enough for me. In rifles with crisp, shiny bores I find I can't do much better than 1600-1700fps. In old rifles with worn, pitted bores I can't get any accuracy past 900fps sometimes.
 
If your cast is bieng pushed too fast, it will cause one or more elements of your load to fail.
Your first indication usually is in your target.

With cast, leads physical shear,and or tensile strength is a limiting factor to the pressure bieng applied to it during the firing sequence. To find out what pressures a load is developing use a good manual like "Lymans cast bullet Manual". They will give you a good idea of the pressures bieng produced.
I use a chronygraph to track the velocities that my alloy tends to start failing.
As you use different powders, you can see how the best grouping tends to be at a certain "range/band" of velocity. On the high/low velocity side, the load accuracy starts to diminish. Performance tends to decay faster on the high pressure side faster.

Start low and work up slowly. With cast bullets as the pressure increases, eventually a load charge will excceed the alloys ability to handle the pressure, and the bullet base extrudes (surpassing the "Alloy YIELD. Point"). Gasses will squirt past between the bullet bearing surface and bore surface causing erratic pressures and acceleration characteristics. Accuracy drops off noticalbly and quickly.
Most powders reccomended for cast shooting are relatively fast burning and apply a fast hard accelleration to a cast bullet.
Finding the right BALANCE of powder charge and alloy composition can be fun!

The "first thing I do before I start shooting lead cast bullets in a given firearm, is slug my barrel to find my exact bore dimensions. (My preferred method, to prove bore dimensions). Or a shooter can just try sizing thier cast bullets .002" larger then the advertised bore diameter.
And lube with a quality lube. And make sure the lube fills the lube grooves completely. The lube offers both lubrication AND support for the accellerating bullet, aiding/assisting in the bullet to bore alignment and combustion gas control.

There is much more to the science of cast bullet shooting than most realise/care to deal with.
With most loads in the Lyman manual you can enjoy some success with some experimentation. Just read up on the subject, and try it out! Its fun as can be! As your techniques develop, so does your results.

Have fun!
 
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In my opinion going from jacketed reloading to cast reloading is a similar learning curve when going from buying factory ammo to first starting out into reloading. You'll already know how it basically works but you'll need to learn a whole new set of little details.
For cast shooting I always recommend the Lyman Cast Bullet Handbook. I also find QuickLoad to be a very useful tool for looking at feasibility and getting estimates before going to the range.
 
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