I was just browsing thru the Speer number 13 manual and noticed that they denote different powder charges for the 100 grain boattail vs the 100 grain flat base in the 243 winchester. They say pressures are drastically different with the boattails. I had never seen a difference like this, other than for a few specialty bullets (Barnes, moly coated stuff, ect.) Has anyone played around with these, or understand what is causing the pressure differences. Their max velocity for a 100 gr boattail is about 2500, which is pretty slow for this caliber.

Jasper243

Look at a bt and a sp of the same wieght from the same manufacture. The boattails almost always has a shorter bearing surface. Which I have been able to stuff a little more powder behind at about same presure. I wouldn't argue to much with a bullet manufacturer. They are betting their business and reputation on their engineers and ballisticians. I'm pretty cocky but I figure they know more than me.