OK. Some tips and explanations.
1) Have you read the fornt half of the lee manual? Cause it explains a lot well.
2) Lee doesn't generate load data, they aggregate load data form powder manufacturers, bullet makers, etc. These sources have different thresholds for safety margin, use different test barrel fixtures, may be reporting about different generations of a given named powder, etc. IMO in this day and age, jsut go to the powder manufacturer's load data page and work from there first. Sanity check it with the bullet manufacturer or other load manual if you are pushing the high end.
3) Check if it is jacketed or jacketed hollow point. Bullet construction affects overall length of the bullet, and surface area of the bearing surface. Longer bullet, less case volume, higher pressures with less gas. More beating surface means more friction, which means more force working against the bullet moving, whcih means higher pressures, which means lower max charge wieght. Lead forms a seal and is kind of sticky when put under those pressures, which is why it has lower max charge than slick jacketed projectiles.
4) In pistol loads, 1 grain is a lot.
I load a lot of plated. IMO you do the following. All are to powder manufacturer data which I find to be the most frequently updated and most conservative. My experience applies to 9x19mm, .40S&W, and .45 acp.
Raineir - load to lead data.
Berrys normal - load to lead data.
Berrys double struck - can load close to jacketed, I'll use similar weight JHP data for a sanity check on max load.
Xtreme - load to jacketed data.
bulletworks - load to jacketed data.
powerbond - load to jacketed data then ask yourself why you are paying jacketed prices for plated.
I stick to either extreme or bulletworks for plated these days. Their plating is thick and their lead is harder than the competition. And the price is right. They are very similar, but not the same.
As a note to trusting the powder manufacturers:
124gr load for CFE from hodgdon is 4.9 start 5.5 max, and it's for their 4" test fixture using berry's 124 plated. You should be safe within that entire range substituting extreme's 124.