Lyman's New 44 Load Data is Just Plain Wrong

[Mal Paso]

When I got my copy of Lyman's new Cast Bullet Handbook I glanced at the 44 Mag load data. It didn't look right and finally, last night compared the data with my load books and my own data. 6 months ago BLT got me started with his spread sheet and ever since I have chronographed every load and each new batch of powder and primers. Lyman reports 70 - 100+ fps Less than Everybody Else.

I don't think Lyman understands Boolit Fit. For the 44 Mag data they used a .429, 4" Universal Receiver and boolits sized to .429. My data with a 4" Colt and a 4" Ruger and Boolits sized .430 - .431 is Much closer to Alliant, Hodgdon, and Speer. My 2400 data covers 4 different batches of powder and the variation was less than 30 fps.

If you throw out the velocities then you have to throw out the pressures as well. Time to get a pressure transducer as well? Please show me where I'm wrong. That I shouldn't consider Lymans Data as bad as their molds.

[felix]

Yes, Mal, a device to measure points along the pressure CURVE would be most welcomed over one that just measured a single pressure peak within the curve. Obtaining the rate of pressure change is highly important in figuring a gun system's vibration pattern. ... felix

[trap shooter]

you got it right fo rme the lyman 4 th is a good untill the reloading data

[Rocky Raab]

The Pressure Trace system is at least as accurate as the transducer systems they use in the lab, and MUCH better than any crusher system. It's also not much more expensive than a high-end chronograph. The problem is that you can't outfit a revolver cylinder with ANY pressure system. It would take a Contender or similar fixed chamber gun to apply the instrument.

[white eagle]

is this the first time that you have seen different
load results from different sources
happens all the time
shouldn't take it as gospel anaway

[bhn22]

A 75 to 100 fps difference is pretty normal. You can have two identical guns, with consecutive serial numbers, built at the same time & one will be at least that amount faster than the other. Throat dimensions are often the culprit.

[fecmech]

The Pressure Trace system is at least as accurate as the transducer systems they use in the lab, and MUCH better than any crusher system. It's also not much more expensive than a high-end chronograph. The problem is that you can't outfit a revolver cylinder with ANY pressure system. It would take a Contender or similar fixed chamber gun to apply the instrument.

Actually the Speer lab did just that back in the early 70's and made a cylinder replacement with a pressure transducer in it. I have a 1973 Gun Digest with the article showing pressure differences between revolvers and solid barrels in the .357. They used both jacketed and cast bullets and even showed the different pressures in the same load by varying the bullet alloy. With some exceptions revolver pressures were higher than solid barrels the majority of the time. The book won't fit on my scanner very well and the alloy data would be of benefit to the board so I will try to get it posted in the next few days.

[mpmarty]

It's a GUIDE, not a bible. I take most all reloading data in books with a grain of salt.

[Rocky Raab]

A single-chamber replacement "cylinder" gun is no longer a revolver. But rather than quibble, let me re-phrase my comment to: You cannot fit a STANDARD revolver cylinder with a transducer or strain gauge because the instrumentation would interfere with rotation and chamber alignment.

Better?

[Larry Gibson]

A single-chamber replacement "cylinder" gun is no longer a revolver. But rather than quibble, let me re-phrase my comment to: You cannot fit a STANDARD revolver cylinder with a transducer or strain gauge because the instrumentation would interfere with rotation and chamber alignment.

Better?

Not quibbling either but it can be done on revolvers. Just a question of sufficient clearence between the strain guage on the cylinder and the top strap. Also whether or not you want to put up with opening and closing the cylinder carefully for a DA revolver or pulling the cylinder on a SA. Additionally you would have to understand that the finish where the strain guage is applied is ruined.

Since I have the ability to measure pressures via a strain guage with the Oehler M43 I have applied 26 guages to various barrels. I carefully considered applying guages to several revolvers but decided to use Contender barrels for my pressure tests of revolver cartridges. I have a .32 H&R, a .357 magnum and a .44 magnum barrel fitted with strain guages.

I don't have Lyman's newest loading manual but I've found the psi figures (not talking CUPs) listed in the last Lyman manual are very close to the psi's I'm getting not only with the above 3 cartridges but with 15 other cartridges. With respect to velociities from revolvers and fixed barrels using equal loads, given relatively equal barrel length from breach face to muzzle, the fixed breach closed barrels produce higher velocities (sometimes much higher) almost all the time over he revolver. This has to do with much longer throats and barrel/cylinder gap in the revolvers.

I concur that Lyman's manual, or any other manual or loading data, is a guide and not gospel. This is why all manualstell us to reduce charges and work up our loads watching for pressure signs that may occur before the listed "maximum" load is reached.

I've posted 2 tests of the .44 magnum (one with both Alliant and Hercules 2400) and one with Blue Dot on this forum. I posted velocities and pressures obtained from my Contender barrel. They are availabl via a "search".

Larry Gibson

[fecmech]

Rocky--I wasn't "nitpicking" you, I just thought that you weren't aware of the work done at Speer and trying to inform you of such. That said, I do believe that pressures derived in that manner would be identical to pressures generated in a revolver with the same loads,throats,cylinder gap, forcing cone angle and groove dia.