Why do these loads seem backwards to me?

[Ohio Rusty]

Here is the info that Hodgdons sent me about loads for the .44 special. (I inquired with them about light loads) I guess this is a continuation of sorts about my earlier thread on reducing minimum loads.

165 GR. CAST LRNFP Trail Boss .430" 4.8 865 10,700 CUP 7.0 1005 12,100 CUP
185 GR. CAST LRNFP Trail Boss .430" 4.5 791 10,400 CUP 6.6 944 12,600 CUP
200 GR. CAST LRNFP Trail Boss .430" 4.3 757 8,700 CUP 6.3 885 13,200 CUP
240 GR. CAST LSWC Trail Boss .430" 4.0 673 9,700 CUP 5.2 763 11,700 CUP

This Data seems bass ackward to me. The lighter boolet, the 165 grainer requires 4.8 grains of trail boss as a minimum load. Yet the 240 grain bullet requires 4.0 grains of TB as a minimum load. Don't you need more power to move a heavier object? A lighter bullet should in theory should require less power to start it's inertia, and consequently a lighter load to get it down range. But according to the data, it's just the opposite. I noticed something else .... Why is it safe to move a 240 grain bullet at 673 fps, but it's not safe to move a 165 grain bullet at that same velocity? The 165 grain bullet is 865 fps. These figures came from a 7.7 inch barrel according to the specs. The 165 grain bullet is the one I'm most interested in for light target work. 865 fps seems too much velocity and recoil for plinking/target fun from a lightweight .44 special snubnosed revolver;(future CCW carry gun), whereas 673 would be much more tolerable and enjoyable to practice with. So ..... What am I not understanding in the above data?
Ohio Rusty

[Bass Ackward]

So ..... What am I not understanding in the above data? Ohio Rusty


Rusty,

I'll take a guess.

I have Quickload. It's just a computer program but I can use the same bullet design and OAL and simply tell the computer that the bullet is getting heavier to see what happens to pressure.

The answer is not much as you might think, which is why weighing bullets has only minimal effect. Or shooting defective bullets might not be a disaster either as long as the bases are fine. The weight altering effect is less in larger bore diameters than small.

Bullet seating depth on the other hand has much more effect. Especially on smaller case for bore designs. Not only does it decrease case volume, but a longer bullet provides more friction surface area for the grip of the case to prevent forward motion of the bullet.

So if you lose case neck tension from a lighter / shorter bullet, you may need more powder for proper / consistent ignition. Which is what I read from your chart and my guess as to why the steady drop.

[sundog]

Rusty, if charge weight remains constant as boolit weight increase, the pressure will increase. Look at the max pressures. As boolit weight increases, charge needs to decrease so you do not over pressure, just like you chart.

Bass is right about SMALL variations in boolit weight not having alot of affect. For example, I was looking at some DP86 date for 30-06 and the start charge of 47.7 was good for 180 and 210 grain cast. Difference in fps was extremely small, maybe 10 or 20. Sensible loading with cast is mostly very forgiving.

The other school of though on weighing boolits however is that variations, especially light, indicate unseen flaws such as air bubble or dross (if ladle or dipper pouring) inside the boolit. Culling these can and will reduce flyers. Is that necessary for plinking loads? Prolly not. For match? Absolutely, as far as I am concerned.

[MT Gianni]

I have no experience with trail boss, but a friend who called Hogdon asking for loads in his 405 Win. was told to measure his bullet from crimp to base, mark a line on the cartridge as to bullet base and fill with powder to the line. Weigh the powder and start at 70% weight as a minium load. Do not compress.Perhaps they consider a lighter bullet in the 44 spl as having more room in the case than a heavier so the 70% start load density is more. This powder was developed with a high case volume, lower velocity in mind so thinking that it resembles another rifle powder may not be correct. Unless you believe it to be a typo, a chronograph is the way to start, which is the way to start all load development. Gianni

[felix]

Fast powders peak very quickly. I imagine the peak pressure for each of these loads would be about the same, or at least in the ball park of one another. CUP measures an average pressure for the most part. The idea of a perfect powder for the application is to keep the average pressure as high as possible while minimizing the peak pressure. When there be multiple peaks, there should only be one which is extremely significant, making all of the others miniscule. ... felix

[Dale53]

Ohio Rusty;
One thing to keep in mind when dealing with powders - "Logic does not always apply".

I was talking to a ballistician from one of the powder companies one time, and mentioned that I was "interpolating" powder charges. He gently reminded me of the above. Powder does not always act in a linear fashion. A particular powder may work "just so" in a particular cartridge with a particular bullet. This does not necessarily mean that a "similar" situation will prevail. The pressure gun oftimes tells us things that do not seem "logical".

We cannot afford a pressure gun for each caliber we load. However, most of us CAN now afford a chronograph (you can team up with other like minded individuals, you know). A chronograph is NOT a full substitute for a pressure gun but you can sure save yourself a lot of grief by intelligent use of same.

Dale53

[dubber123]

The formula MT Gianni quoted is the same I was given, and has worked very well for me, even with 180's in a 44 mag. (3/4" or less at 50 yds, 10" TC). They did tell me this formula was for straight walled cases only.

[frank505]

In a 500 Linebaugh with an 8" barrel and a 450 grain Keith bullet 9.2 grains does 760 fps at 19000 psi. This from Hodgdon's pressure gun.
We tried 10, 11 and 12 grains without the benefit of a pressure gun. The velocities did not increase! Probably all revolver cartridges peak before the bullet leaves the case so I think T.B. can only move so much because it is so quick.
454 and the 270 work at the same peak pressure, the 454 does it all in the case though. That is from one of the ballisticians at Western powders.