I've been developing some loads for my 4" 500S&W, and I seem to be getting odd results. Here's what I've been doing... I'm following Hodgdon's recipe to the "T", Starline Cases, WLR primers, 385gr Rem CLHP. Hodgdon suggests a starting load of 38.0gr of Lil Gun, and a max load of 41.0gr. I loaded up from 38gr to 41gr and found that 40.0gr produced acceptable accuracy at 25yards. No problem, right?!? Well, I chrono'd 5 rounds this evening, and here's the velocities: 1493, 1535, 1594, 1555, 1545. That seems like quite a bit of excessive spread between high and low, and the velocities are quite a bit more than I had expected (each charge is carefully weighed out). Primers are somewhat flattened out, but not excessively. Cases extracted very easily, and primer pockets are still nice and tight. These velocities were taken 15ft back from the chrono. All loads have a heavy crimp. Do you think I've got an extra hot batch of Lil Gun and pressures are to the point were velocity is becoming erratic? Any experience or insight as to what I may be missing would be appreciated.

Could be heat.

A buddy of mine has a .500 and it will stick cases in the cylinder if you fire it too quickly. The cylinder heats up. I guess it's possible the heat from the cylinder is generating the pressure. It also slightly flattens primers with about the same of lil-gun.

Although more likley you need to look at your crimping for spreads like that.

This is where a chronograph can get you into trouble with too much intellectualizing.

If the load is accurate, don't worry about how much velocity spread there is. Furthermore, in my opinion, your velocity spreads are quite acceptable.

Also, don't worry about what velocity is in the manual compared to what your gun gets. The only things that are important are that the accuracy is acceptable in your gun and that the pressures are acceptable in your gun. The primers should be flattened a bit, there shouldn't be too much powder residue in the barrel (a sign of too light a load), and the cases should extract easily.

In the case of a straight walled case like the 500 S&W, hard extraction would probably be a sign of case expansion in the head area; a sign of much excessive pressure.