Same powder, two recipes

[hswaters]

I have some IMR SR7625 powder. I got what I could find and I am not knowledgeable enough to have a preference for any particular powder or manufacturer. I looked for reloading information when I got the powder and found a PDF on 10-4-2013 from IMR that said 230 lead, .451 dia, COL 1.270 min 5.8 max 6.2 gr, velocity 825.

Then recently I found another IMR specification that says 230 gr LRN, .452 dia, COL 1.200 min 5.5 max 6.0, velocity 897.

No mention of how long the bullet might be. I have a commercially made lead PC bullet that is .685 long and .451 diameter and some home cast Lee tumble lube bullets that are .661 long, .452 diameter. Both sizes may vary a couple of thousandths in length.
It sure looks like the first one refers to the commercial bullet and the second one to the Lee.

Winchester FMJ factory made are 1.262 COL
So I thought I would find out what you old hands think about this. Maybe you can explain how to be sure I have the right over all length as it appears that bullets of the same caliber vary quite a bit in length.
I am a poor old dumb redneck so please type slow because I read slow.

[Love Life]

For a 230 gr LRN I'd load to 1.250 and call it good as long as it passes the chamber test. Crimp. .468-.470.

You can actually seat as far out as you want as long as it will fit in the magazine and pass the "Plunk" test.

Start from the start charge and work up.

That should get you up and running.

[Wayne Smith]

Those two load specifications are close enough that almost anything could have made that difference. Atomspheric pressure difference, altitude of the range used, barrel length or a different gun with a slightly tighter or looser chamber or barrel. Different lots of powder or primers could have been the difference.

[Mk42gunner]

hswaters, the main difference I see in the data you posted is the overall length. Seventy thousandths of an inch doesn't sound like much, but it is when you are talking about a combustion chamber that is .451" diameter.

I'd use the data for the longer length, if it were me.

Robert