If you sift gently through the rancor, the Wildcatters have some very good points....following is JMHO so take it for what it's worth and remember what you paid for it....
First'I'm no expert but suspect a lot of things,like a lot of the load work up in loading manuals is done in special pressure barrels that may deliberately be built somewhat "undersized", which means they are tighter,ie a 270 pressure barrel may mike .276 through the grooves,maybe more or less,but the point is that in working up loads for
thier particular bullets Nosler, for example, or Hornady for another,want to be sure their data is "safe" in a wide variety of rifles whose barrels may be "tight",exactly to spec, or a bit "loose".
What I'm saying is that barrels vary in dimensions of bore and groove diameter;and bullets vary a great deal in hardness of jackets, material,diameter(mike a Partition sometime),length of bearing surface, etc.
All of these things can conspire in one direction or another to make manual data for a given cartridge not give precisely the same velocity/pressure ratio that the manual suggests.
Plus, these guys who wildcat usually do so with finely squared up actions, and super accurate custom barrels with special throating (because reamers vary a good bit, too). So they get a Lilja(say)that may be on the "tight" side....and mix it with bullet having a longer,full diameter, bearing surface,work up to manual "max",and discover that they are outrunning manual velocities but 100-200 fps....
Factor in what JB has said many times about precisely built,blueprinted actions and barrels that do not demonstrate high pressure signs in the same manner as a somewhat sloppier factory/barrel combination,and you can wind up with a situation where the rifle delivers higher than "normal" velocities at pressures that appear safe based on case life, primer pocket expansion, etc.
Conversely,we take another combination of bullet/barrel that may be "looser,or have a slicker bore(smooth,custom),that when mixed with a bullet that is a half thou undersized,and this combo may allow the use of loads that dramatically exceed the loads listed in the manuals as ""max";and may give more velocity in the process......
It is entirely possible to run into barrel/bullet/load combos that demnstrate
excessive pressure yet
do not deliver the velocity considered normal for the cartridge.
And always remember those finely built actions and barrels and their effect on the velocities and max loads....
None of this is meant to say that loads giving extra velocities are always above or below SAAMI pressure spec, because most of us do not have the equipment to precisely measure pressure of given loads.I mention this just to make us think and remember that rifle/bullets vary greatly in the way they interact,the velocity they deliver,and the pressures they generate.
I am not much of a wildcatter myself(although I am having one built right now) but the guy who builds and shoot these things routinely is almost always more likely to encounter these varied situations than those who stick pretty much to factory-built rifles and manual loads.
I think this is what Keith and others are trying to articulate and if they think I am wrong they can wang away at me too!LOL!
