westerner wrote on Nov 22^nd, 2022 at 3:33pm:


Joe I have a cast #2 chambered in .32-40, and re-rifled to open it to .318" groove. I also have shot it a bunch, and am not afraid of it with my loads.

why waste time and money on something that is marginal?jmo  art

Smokeless or BP depends on which smokeless powder you use. Some smokeless powders have lower operating pressures than BP has, and have pressure curves more gentle like BP has. So to say all smokeless powders are bad really isn't accurate.
I also know a guy who has a cast Ballard barreled to .40-65 Win. which really freaks me out! He's shot nothing but BP loads over 20 years, and I keep waiting to hear it's finally given up and cracked, but so far it's holding. This isn't saying it wont eventually, and when it does it wont gradually give warning signs before it happens.
What I'd own and shoot is my personal choice, and it's often different than what I'd choose to build up. What I might buy and shoot isn't always what I'd build to shoot.
Wonder how many factory built Stevens 44's in .38-55 and .32-40 are still out there being shot and still working well? Yet most people wont chamber the 44 in either of those cartridges, yet they'd own and shoot an original.

uscra112,

When I posted the muzzle velocity of my 120 gr. Mos bullet breech seated at 1660 fps I neglected to add that I was using 9.6 gr of AA4100 powder. I wonder if that makes a difference in the pressure and thrust? Also, what would it be using my 25-20 WCF case?

JerryH wrote on Nov 23^rd, 2022 at 11:28am:


Thinking about it strictly as an engineer, muzzle velocity can be said to depend solely upon a concept called specific impulse, which in this case would be the integral under the pressure/time curve from moment of ignition to the exit of the bullet from the barrel.  A fast powder, to deliver a given MV, has to create a high initial pressure because the curve will tail off more rapidly than, say, 4100, which maintains pressure for longer, so it doesn't have to start with such a high pressure.  I wish Quickload would calculate this parameter, but it doesn't.  You can only infer from eyeballing the pressure/time graphs it prints.   

The role that case shape and volume play constrain the amount of powder and the efficiency with which it burns. The two .25-20s are very close in case volume, so you can compare them. According to the QL database, the Stevens case has a bit greater volume than the WCF (who knew?), so to get the same specific impulse you have to increase the 4100 charge by 0.2 grains. Peak pressure almost exactly the same, as it ought to be.

Now try for the same MV with AA#9, which is only a little faster. The charge has to drop to 8.9 grains, I think because #9 liberates a bit more heat per grain, and peak pressure goes up by ~3000 psi. 

Case shape is known to influence burn consistency, alll other things being equal, which may help explain your success with the WCF case, in spite of its' slightly smaller volume.  A factor that the QL model doesn't take into account, as far as I can see.  

There's a lot more you can learn by playing around with QL models, but I'm out of my depth when trying to explain it all. 

Most reloaders would benefit from a ballistic loading program that not only gives velocity and chamber pressure, but just as important the pressure curve, which shows us how a smokeless powder arrives at a certain pressure level.
I never used one of these programs because I told myself I used mild smokeless loads, and have been reloading for well over 4 decades. But a friend pointed me towards a free ballistic program, and I figured nothing to lose when it's free.
Being able to enter all the data on my guns, powder charge, bullet weight, etc., and get velocity, chamber pressure, recoil, and see a graph of how the load reaches max pressure is a great tool! I found out that some of my favorite powders weren't high pressure, but had quite a spike getting to whatever pressure. So the pressure spike was more like a sledge hammer, than a heavy push to reach maximum.
I now run all my old data through the program, and although I haven't changed my loads, since they're within safe limits, I have used more of the powders I was already using that showed low pressures, and gentle ramps up to the pressure.

Thanks Charlie! 
I had no idea there was a group actually firing these old guns also.