OAL irrelevant?
OAL is not the critical dimension. The volume UNDER the bullet is.
The only reason we use OAL (overall length) is that we cannot directly measure the volume under the bullet on a loaded round. So, the OAL is a proxy for the distance from the bullet's base to the bottom of the inside of the case.
Please don't tell me it either bullet is a hollow base bullet. That would add another element of complexity.
So, to be more confident that you are within specs, you have to do some arithmetic.
1) Measure the length of your 158 grain RNFP (round nose flat point) bullet. Write that down. For best results, measure several and get an average.
2) Look in your loading manual for the length of the 158 grain BULLET they cite.
3) Subtract THEIR bullet length from their cited cartridge OAL and add YOUR bullet length.
That should be your cartridge's OAL.
If it is off from that figure, then you can adjust your powder charge to accomodate the difference in pressure you can expect.
You will have to consult with ballisticians more educated than I am to get recommendations of how much adjustment to apply, because the adjustments are not straight proportions.
If you want to put an even finer point to it, note that the bearing surface of the bullet on the barrel also will affect the pressure, but that is probably too fine a distinction to matter much.
Just watch the bullet weight and that free space under the bullet. The pressure is inversely superproportional to the volume and can get dangerous if there is too much OR too little free volume.
Good luck and thanks for asking our advice. Post dimensions if you want me to go further.
Lost Sheep
p.s. I do agree with most of the others' advice here. Seat to the crimping groove. Most of the time, the position of crimp groove has been adjusted so that the nose shape's effect on the free volume is nil. All my arithmetic usually does is confirm that the folks who designed the bullet shape were paying attention.
If these bullets caused gun blowups, they would disappear from the marketplace pretty quickly. So, seldom is it necessary to adjust the powder charge for case volume.