Factory vs mine and yours

[RB98SS]

I was wondering whilst pondering my reloading manuals the other day, why its always "advised" to start your new loads from the bottom and work up "carefully". Now I'm certainly not going to dispute the fact that it seems good advice. but looking at data from factory ammunition and comparing it to reload data it would appear that top end reload data puts your velocity right at factory listed velocities. In .44 magnum in particular, Remington, Federal, Magtech and Winchester all have printed velocities at around 1200fps with their 240gn SJSP's.

If I look at my Lyman 49th, all of the top listed loads are right there too. The top load being at a velocity of 1292fps with H110. The top factory load at 1230fps with Federal ammunition.

I spoke with a rep at Magtech and he said that the velocities listed on their site were with a 4" barrel and that SAMMI sets the test specs for them. He also said that he was pretty sure that the other manufacturers used the same test setup. It stands to reason.

So being that the only reload manual that I own that has data listed for a 4" barrel is the Lyman 49th, that is what I went with.

I'm not sure just exactly what I'm trying to convince myself of, but wouldn't it be safe to say that a person could -- with relative safety -- load right up there at the top as long as the components listed were the components used? I understand that once you start mixing components then the sky's the limit as to what can be expected.

It just seems that there is a lot more caution and advice given to a person reloading than there is to a person just going out and buying a box of "shells"

Sorry for the long wind.

 

[Steve C]

The reason that why its always "advised" to start your new loads from the bottom and work up "carefully is that there are enough variables in cases, powder lots, primers, and bullets that any particular combination results in enough unpredictability of pressure that its not safe to just pick the maximum load not withstanding accuracy. With any different component from what is listed, including a different lot of powder you could wind up with a dangerous overpressure load at or near maximum.

Since loading manuals are used by people using variable components of different manufacture its advised to start at a lower, presumably safe level and work up to maximum velocity. Optimal accuracy on the other hand is often found at a completely different load than the maximum.

Factories use bulk powders and load using laboratory based testing. Just for fun pull a couple factory rounds of the same brand from different boxes of ammo sold at different times or with different lot numbers, pull the bullet and weight the charge. I think you'll see that their loads are quite variable in charge weight, often within the same box, but their velocities are quite constant if you chrono the loads.