Lyman load data in conflict with itself.

[wallenba]

I'm getting a bit confused about Lyman reloading data. Nearly all of the cast bullet rifle data they list uses Lyman #2 alloy. It lists a normal BHN of 16 in most references I've found. It has a max pressure of 20,433 PSI. Yet Lyman uses it, and routinely exceeds the limits, even at starting loads. I have been blissfully doing it in my loads with no problems. I would like to understand the 'whys' so I can feel more confident in using this data. Can anyone explain?

[williamwaco]

You are misunderstanding the "rule".

The most accepted "rule" is 1422 times BNH. You seem to be using about 1277 times BNH. The lee manual chart listing maximum pressures uses a factor of 1275 to 1280.

That is the calculated average pressure required to expand the bullet to obturate.

It is not a maximum pressure at all.

A few people insist this rule will get you maximum accuracy. My experience shows NO relationship between this "limit" and accuracy in handgun loads. I get best accuracy in magnum handguns at loads around 100 fps below max.

Bullets cast of Lyman No. 2 are routinely reloaded to pressures much greater than that.
The original .44 magnum loads were developed with an alloy of BNH 10 and were developed to about 34,000.


.

[geargnasher]

Who said Lyman pays any attention to some theory Richard and John Lee established?

Gear

[wallenba]

I just quoted the BHN chart supplied by Lee with my tester. 16 BHN is the max @ 20433 PSI. Yet Lyman is using it with the #311642 mold for 30-06 with Unique. The start load is 18 grains and developes 34,300 PSI.
16 times 1422=22752

'Who said Lyman pays any attention to some theory Richard and John Lee established?'

Gear

If that is the consensus, I'll run with it. What's the worst that can happen?

[Larry Gibson]

Ignore the rule, Lyman does and so do a lot of us. Lee's Rule works sometimes but mostly it doesn't.

Larry Gibson

[wallenba]

Ignore the rule, Lyman does and so do a lot of us. Lee's Rule works sometimes but mostly it doesn't.

Larry Gibson

If it's good enough with William, Gear and Larry, it's good enough for me, thanks. I'll just relax now.:grin:

[runfiverun]

lee's maximum is about where i like to start from.

[geargnasher]

Actually, I disagree with Larry on this one, or maybe we do agree, I don't remember!

My experience, having done a lot of "theory testing" is that if you adhere strictly to Lee's BHN/PSI suggestions and some common sense with powder selection and boolit fit, you will practically have 100% success and highly accurate loads. I've verified an accuracy "sweet spot" around the zone between yield strength and ultimate compressive strength of the alloy in several rifles, but I can only estimate chamber pressure since I don't have any pressure measuring equipment.

However, if you choose to ignore it and find out what works for yourself, you'll also find that you can do much better with velocity and accuracy than the Lee formula would indicate. There's a LOT more to loading accurate, fast cast boolits than a simple alloy strength measurement. There's a lot more to alloy than it's strength, too, which is my main beef with the oversimplified Lee method. 15 BHN can be achieved any number of different ways with composition and temper, and each makes a difference on how the boolit shoots. I routinely shoot loads at double or more the measured alloy strength. Boolit fit and pressure curve is what gets me there.

My point is that Lyman doesn't seem to observe any pressure/hardness formula in any way when they publish load data, so I don't see why there's a contradiction within Lyman's methodology.

Gear

[btroj]

What? A few simple numbers don't dictate what works?

I get around worrying over the "Lee Rule" by not owning a hardness tester. I figure if I don't know for certain the BHN then I can't know the ideal pressure and fret over it. Seems to work.

I just do what Gear said, use common sense and past experience to guide me. Seems to work quite well.

[44man]

Ya know, for many years now I have never found anything from Gear that I disagree with, Larry either! :redneck:
This is again one of those times.
If I have a gripe it is that they explain things better then I do! [smilie=l:
I am one of those that never believe in theories. They MIGHT help a man starting out but I still question that.
After shooting cast about forever, the target and group will tell you what change in alloy will improve it. You can't find that in a book.
That might be the most important reason to never buy store bought boolits, make your own.

[Larry Gibson]

Lee's Rule works sometimes but mostly it doesn't.

Gear and I agree.

Larry Gibson

[pdawg_shooter]

I have yet to try an alloy that cannot exceed Lee's formula by at least double, with accuracy.

[wallenba]

[QUOTE=44man;1718431]Ya know, for many years now I have never found anything from Gear that I disagree with, Larry either! :redneck:

Me either. That's why I'm relaxed now.:-)