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Thanks for the advice on the 300 WFN in the 454 Casull.  The groups have shrunk some, although not as much as I'd like, but they do seem rounder.  I have gone up to 33 grains of H-110 in my Freedom Arms and the cases still come easily out of the chambers and the primers show no sign of flattening.  I haven't been above published data much before.  Can you measure the base of the case before and after firing on a hangun cartridge like a bolt rifle?
 

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Those Freedom Arms guns have a very tight tolerance in their chambers so you might not see any real expansion of your cases. You can take those guns up a few more grains with a 300gr LBT and still be safe. They are absolutely brute strong. If my Ruger can take 35.0gr a Freedom Arms can take even more. On a gun with very tight tolerances you won't see much in the way of pressure signs. Even stock factory guns have been blown up and still showed no signs of pressure. On your Freedom Arms gun you will probably give out before the gun does.

God Bless

Chris
 

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Ditto what Chris said. Take a look over at John Linebaugh's web site. He claims that the rounds that were shot right before he would shot a round that blew up a Blackhawk cylinder fell out with no extraction problems. Primers? I have had primers "melt" around my firing pin on my FA using 31 of H110. Some primers are tougher (or softer) that others. Bottom line- work up slowly and use the info from people like Marshall.

Mark
(Casullian)
 

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Bob,

You'll find that in determining maximum safe working loads, the information so far given here on the forum is good sound advice.  The cautionary statements about the tight tolerances of the FA revolvers not producing significant case head expansion is very true.  Primers, especially in the Casull, are a poor indicator, as you are using rifle primers in a handgun case, the primer cups are significantly thicker and tougher than are handgun primers... consequently by the time you get pressure signs via the primers in the .454, you are well into dangerous waters as a rule!

What I would like to add to what has already been suggested is this:  USE YOUR CHRONOGRPH!!!!  if you don't own one, wait on other shooting frills, and go spend the bucks and buy a &#3670 Chrony!

Why?  Because that chronograph will tell volumes about your load status!  In using both H110/W296 as well as AA1680 in your .454 Casull,  yes, those powders thrive on pressure, and reach their most efficient burns at the top 5% of the pressure envelope.  You can use this to your advantage in determining optimum loads with your chrono.  You will notice a few things happening as you are cautiously working up a load using these powders.  First, pay special attention to the ES when shooting strings during a load workup.  In loads that are well below the upper end of the pressure envelope, there will be large, and sometimes very large ES readings.  As you begin to approach the best efficiency threshold, those figures will drop, sometimes right into the single digits!

Once into the low double digits for your extreme spread figures, then go slowly, as the sweet spot will only be a few tenths of a grain one way or the other on a good load for peak efficiency.  I rarely have tuned a load with these guns, where when the ES over the chronograph showed single digits, that accuracy wasnt' very good to superb!

Now, another essential tell-tale sign to look for is velocity increase when upping powder charges incrementally.  At the low pressure end, you will see very little change in small powder charge increases with H110/W296 and AA 1680, then as you begin to appoach the pressure envelope that produces efficient burning of these powders you will observe significant velocity jumps with negligable powder increases.  As you begin to increase charges, and the velocities are climbing, rather predictably with inch upward increment, you will also see the ES figures dropping.  Somewhere in this progression, you reach a point where the load does what I refer to as flatlines, where powder increases give very little to no velocity increase for the extra fuel added to the fire.  At this point stop!   Absolutely stop!  You have reached a point where the load has maxed out the efficient burning threshold of the volume of powder loaded.  Any increase in powder at this point is only spiking pressures!

Now, after having taken detailed notes during your load development, you should see a pattern developing of velocity to powder in the form of progressive increases.  This trend is most easily evaluated when you plot your powder vs velocity on an X-Y graph in a good spreadsheet program.  This way you have a graphic representation of the velocity curve in relation to your powder charges.  Now, if you also plot your ES figures for the same loads on that X-Y graph, that point where you have the lowest ES, with velocities that are proportionatly increasing with added powder will be your top, safe load that will also have the potential of being your most accurate load in terms of burning efficiency.

From this established point you can tinker with a few tenths of a grain one way or another to fine tune the load on paper.

Now, having said all this, it is very applicable to the .454 Casull since it operates safely at the high pressure thresholds was designed for!

I hope that this helps you, and others as well.  This method is much more reliable than many of the other traditional "max load" tests.

Be safe and enjoy!

God Bless,

Marshall
 

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Most excellent post, Marshall!!!! You might add that is an excellent method for developing the best rifle load with any given bullet weight\type of powder. Homer Powley found, with IMR powders, by adding one unit of powder, you got one unit of velocity increase, but two units of pressure. Other words 1% increase in powder (IMR) gave a 1% increase in velocity, but 2% increase in pressure! Quite frankly, I don't if the same applies to handgun cartridges? I've often wonder how Expansion Ratios applied to revolvers with the cyl/barrel gap? I do know powely's work applies to handguns like the Contender.I have seen vented pressue guns used to test revolver loads.
best Regards from the Hammock....James
 

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Marshall, I've been using that system ever since I got my Oehler model 12 chronegraph over 20 years ago. I thought I had a scoop. I don't have any hardcore handloaders living nearby to swap notes with, so this forum is great. I also use a .0001" micrometer to measure cartridge bases when working up rifle loads. Good tip about the graph, Didn't think of that...thanks,  
 
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