Load Data Confusion

[hylander]

Subject is .243 with IMR 4064 powder and a 100gr. SP
My speer manual shows
29.0 - 33.0
Hornady shows
29.4 - 34.2
And IMR website shows
33.0 - 36.5

Hornady and Speer are fairly close
But IMR shows a starting load where Speer shows a max load  :?
I'm looking for an Accurate load, Where to start ?

[Ifishsum]

When in doubt, I'd go by the data of the bullet mfgr that I'm using for that load because that's what they used when they did their pressure tests.

[Grumulkin]

I also would give the bullet manufacturer's data the most credence.

In this case, there isn't that much of a spread in powder weights between minimum and maximum charges.  I would start at 29 grains and work up from there.  I would use the powder manufactures maximum load data for reasurrance if approaching bullet manufacturer maximum loads with no signs of excessive pressure (i.e., I might cautiously push the load a little further if I thought accuracy might benefit).

[ricciardelli]

IMR-4064 From 29.0 grains to 38.0 grains
 Remington 9-1/2 Primer

[Val]

The differences in the load data is one of the reasons we start with a low powder charge and work up, looking for signs of too much pressure.