.45 ACP light bullet loads

[another okie]

I'm a beginner.
I notice in the Speer manual that the loads for the Speer GDHP are much heavier than for almost anything else. I guess my natural thought would be that a 185 g. bullet like that would require less powder. There's not really an explanation. Reading over the manual I do notice it says that you can load lead bullets a little lighter than jacketed due to greater friction and more danger of a bullet stuck in the barrel. Is this the reason?
(Example: 7.4 grains of 231 max for the 185 gold dot, 5.6 for 230 grain lead round nose.) Is there some other reason?

 

[Jim Watson]

Apples and oranges.
The lead 230 is cheap and soft, intended for practice ammo. Heavy loads would just cause it to lead the barrel and recoil more.
The 185 GDHP is a hollowpoint mankiller, meant to be driven at high velocity for maximum impact and expansion. That takes more powder.

 

[E357]

The loads you see listed in most manuals are based on pressure values. For example in the 45 ACP most manuals list loads that are about 19000 PSI. A heavier bullet like a tighter "cork in bottle" needs less powder to reach the desired pressure. Because of physical laws, the same pressure applied for a similar time will drive the ligher bullets faster than the heavier ones.

The speer GD bullets (very accurate) are plated and I find they load and shoot more like a very clean lead bullet rather than a true jacketed roiund.

Elliot