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Very Hot Topic (More than 25 Replies) sub for 4759 (Read 1823 times)
uscra112
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Re: sub for 4759
Reply #15 - Sep 1st, 2017 at 5:52pm
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Out of curiosity I compared the pressure curves for 4227, AA#9,  and 4100 in Quickload, using the .25-20 SS cartridge model.   QL has no data for 4759.

They all reach peak pressure at the same time, 0.5 milliseconds, given loads for equal pressure..(~12,800 psi).   

4227 appears to have a tiny bit of a "fat tail" to the curve, by comparison, which nets about 40 fps more velocity for the same peak pressure, calculated for a 24 inch barrel. 

Maybe I can figure out tonight how to get the comparison into a single graph.
  

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calledflyer
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Re: sub for 4759
Reply #16 - Sep 1st, 2017 at 5:59pm
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So, uscra112, that means that to get the same velocity with the "new" powders one would have to operate at higher peak pressure. Correct?
Sure would be  nice to see how the discontinued 4759 would have compared. Meanwhile, I ration my dwindling supply, standing at just over three pounds. And, thank heaven for 4227.
  
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boats
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Re: sub for 4759
Reply #17 - Sep 1st, 2017 at 6:22pm
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4759 or 4227 I have found differences lot to lot with either powder so close one lot of 4227 will be hotter than 4759 grain for grain, another lot the reverse,

This observation by strike on target same sight settings. Of course other factors could have produced the result. Ambient temp for example

Still they are very close

Boats
  
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oneatatime
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Re: sub for 4759
Reply #18 - Sep 1st, 2017 at 7:15pm
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uscra112, how about comparing the pressures at equal velocities rather than the velocities at equal pressures? The point for older rifles wasn't to get the most velocity at a pressure but to attain a black powder velocity at a lower pressure. For fun you might throw in 2400 and Unique also.
  
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westerner
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Re: sub for 4759
Reply #19 - Sep 1st, 2017 at 11:33pm
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Try a double charge of Unique! Just fill the case with Unique. That would fall outside safety constraints? Is that what you mean?  To hell with safety constraints? Personal safety constraints............thus......... POOF! CABOOOM!!

Just my two cents.


               Joe.


      


            
« Last Edit: Sep 2nd, 2017 at 12:30am by westerner »  
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uscra112
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Re: sub for 4759
Reply #20 - Sep 2nd, 2017 at 4:58am
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oneatatime wrote on Sep 1st, 2017 at 7:15pm:
uscra112, how about comparing the pressures at equal velocities rather than the velocities at equal pressures? The point for older rifles wasn't to get the most velocity at a pressure but to attain a black powder velocity at a lower pressure. For fun you might throw in 2400 and Unique also.


Well, the examples I cited all calculated to 1390 fps from a 24 inch barrel, give or take 10 fps or so.  (Within the error budget of the model, I would think.) 

You have a point, however.  Powders much too fast for a given application will produce higher peak pressure when loaded to a chosen velocity. 

Unique, loaded in the model to 1390 fps, calculates to a bit over 21,000 psi.  Red Dot is even worse.  I want to guess that this is related to the total volume of gas evolved.  The pressure curve for these powders falls off dramatically faster than the 4227 family.  (If I remember my integral calculus right, the velocity would relate directly to the area under the curve, assuming you ignore friction losses.)

But 2400, again loaded to 1390 fps, calculates to 12,900 psi. 

This is why I feel that the Government should be required to issue a copy of Quickload to every reloader at taxpayers' expense.!   Wink    I never look at paper manuals anymore.  And since you can create your own cartridges, it's perfect for our old crocks for which loading manuals never even existed.

Funny thing, by the time I needed to use calculus for engineering problems, there were computers to do it for me.  Later on I made extensive use of a function called the Fourier Transform, which I could not write a proof for to save my life, but no matter, just load the data into the software and push the button!  I don't have a clue how Quickload's model works, either.  But it does.  It's never been far off when I get to the range. Usually a bit on the conservative side, so I wind up tweaking the load up, not down.  It even made a fairly accurate velocity calculation for when I fired a double charge of AA#9 across the Chrony once upon a time. 
  

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KAF
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Re: sub for 4759
Reply #21 - Sep 2nd, 2017 at 8:20am
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I am sure the photo of the hi wall pieces is called a catastrophic failure.
  

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40_Rod
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Re: sub for 4759
Reply #22 - Sep 2nd, 2017 at 8:53am
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4100 when loaded to appropriate levels is perfectly safe for a 25-20 i have shot it in a SDtevens 44 1/2 with no sticking or other problems.

40 Rod
  
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Schuetzenmiester
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Re: sub for 4759
Reply #23 - Sep 2nd, 2017 at 12:47pm
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oneatatime wrote on Sep 1st, 2017 at 3:34pm:
Schuetzenmiester, just so no one gets the wrong idea, the pressure curves for 4759 and 4227 are similar to FFg and FFFg AT BLACK POWDER VELOCITIES not that they can be loaded grain for grain.

Good point.  You never now how inquiring minds will interpret a statement.
  

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Re: sub for 4759
Reply #24 - Sep 2nd, 2017 at 5:10pm
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A 25-20 load that starts sticking in a Stevens 44 has gone well beyond the clear the range point in my book. Unfair to compare it to a 44 1/2.
  
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uscra112
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Re: sub for 4759
Reply #25 - Sep 2nd, 2017 at 7:07pm
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oneatatime wrote on Sep 2nd, 2017 at 5:10pm:
A 25-20 load that starts sticking in a Stevens 44 has gone well beyond the clear the range point in my book. Unfair to compare it to a 44 1/2.


That double charge of #9 I mentioned?  .25-20 SS in a Model 44.  80,000 psi according to Quickload.  I didn't even notice anything wrong until the case wouldn't extract.  The primer fell out.  The rifle is OK.  Freshly rebarrelled and everything set up right, though.  Loose and shaky one maybe not so good. 

Needless to say I won't let it happen again.  Couple more like that and I'd be looking at the headspace opening up.  The hoop strength of the barrel in that small caliber was/is enough.
  

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Re: sub for 4759
Reply #26 - Sep 2nd, 2017 at 11:37pm
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Also, the 2520 head area is small for lower backthrust on breechblock
beltfed/arnie
  
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Re: sub for 4759
Reply #27 - Sep 7th, 2017 at 5:35pm
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Anyone used Lil'l Gun in .32-20's to get up to 1300 fps or so?
  
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uscra112
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Re: sub for 4759
Reply #28 - Sep 7th, 2017 at 6:38pm
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lars wrote on Sep 7th, 2017 at 5:35pm:
Anyone used Lil'l Gun in .32-20's to get up to 1300 fps or so?


Not I, but I'll report that in my experience Lil'Gun wants a little more pressure than that to be consistent.  Above 20,000 psi.  Not knocking it - it's wizard in the Hornet.
  

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Re: sub for 4759
Reply #29 - Sep 8th, 2017 at 4:53pm
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Thanks, I'll stick to the AA#9 then.  Have only a half pound of 4759 left.  Saving that little bit for other useage.  Found the Lil'l gun so great in my .22 Hornet that I was thinking of trying it in the .32-20 as it's a small capacity case.  Way different in bullet weight though.  Using a 205 grain Hock mold.
  
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