ok, mouse had most of it correct, but actual P.O. did get the gains he claimed, mostly because he was running his wildcats overpressure.
Most reloaders know that when you see the signs of pressure they are as follows
1) flattened primers
2) ejector pin marks
3) quickly accompanied by sticky extraction and heavy bolt lift
Well if ya start shooting an AI or any sharpshouldered case with a custom reamer without all the slop built in, you don't see this. without the 23 degree shoulder and alot of body taper acting like a tapered wedge pushing against the bolt the first pressure sign you notice is the ease of seating a new primer. this means casehead expansion and that is the #1 sign of over pressure.
In other words, when you notice pressure signs in an AI'd chamber, that case is much closer to failure than a 30/06 with ejector pin marks.
without running them over pressure for gains in velocity, the main advantage to an AI chamber is the fact that the sharp shoulder holds back the flow of brass so trimming is held to a minimum.
RR
