SmallCaliberCentral

does reloading data for bullets of the same weight but differant designs vary? For example, is the reloading data for a 32 grain sierra the same for a 32 grain V-max?

Ruger #1 . From what I have learned. Bullets of the same weight can use the same powder charge. If you measure to same diamater on the bullets ojive you might see one loaded round might have a longer COAL. Were I have found a pressure problem is in bullet diameter being slightly larger than the rifles bore. For example a .204 cal bullet measuring .2046 and haveing a spec bore of .2041 in your rifle. This would happen if your running a max change in your rifle and have a real tight bullet.
Hope this helps a little.
Later
Ray P

No.1: Ray is correct, but the real issue is in using max or close to max charges from say the Nosler manual for the 32gr bullet, but shooting the Sierra 32gr for example. The issue is BEARING SURFACE of the bullet. The weight may be the same, but a different pressure curve will result because of differences in the bearing surface of the bullet.

If using a different manual than the brand of bullet you are shooting, I'd recommend dropping the charge back at least a full grain to be on the safe side. If all looks okay, increase the charge carefully .3 or .5 grains at a time.

Our good friend Silverfox posted some very informative photos of various 204 bullets a while back that illustrated this issue. Bullets from the four makers were shown, all the same weight, but the bearing surface was different on each bullet. A longer bearing surface will raise pressures because of the increase in drag against the rifling.

Thanks guys!

Thered are so many variables involved in reloading that no single manual can allow for all of them. Bearing surface of bullets has been dealt with here, but there are many more that can change pressures: powder lot, barrel length, chamber and bore dimensions to name a few. Most manuals will state what components and test equipment were used. It is important to use this information as a guide (instead of treating it as cast in stone) and start low with any combination (or change) of components and carefully work your way up. Each gun will have its own individual quirks and preferences and they may not exactly match published data.