My 6.5 WSM will be done in the next two weeks. I am inquiring if anyone has any input or opinions as what or how they would find starting data. Would you look at like data for the .270 WSM with same weight bullets, reduce slightly and start, or try to calculate data from case capacity differences vs. the .264 Winchester.

I intend to start and use 140's in either Nosler of Hornady exclusively.

Can any of the computer programs calculate data for non-existing wildcats that have similar case capacities in the program???

Sorry cannot help

martin

Anyone with Quickload or Calcu-Load should be able to whip up some starting loads in short order . A number of us folks here have Loadbase with the Powley computer feature which will get you starting loads for IMR powders . You need the water capacity of your cases and the bullet length to do the calculation ......

According to QL and using the 264Jamison cartridge(81.0grs of H2O),it yielded the following with 140's and a 24" tube.

61.5 grs of Re-22,generated 3008fps,at 55K PSI. 63.5grs of same,granted 3100fps on the nose,at 61K PSI.

That is not a recommendation,nor reference material. Consider it food for thought...............

I have built two 6.5 WSM. My father's has a douglas barrel. Mine has a rechambered PACNOR barrel. PACNOR's barrel has an inner diameter of .256 compared to Douglas' which is around .257. Both are 27" barrels with 1 in 8" twist(initially thought we would use larger VLD bullets). This has produced markedly different load data. All has been tested with peak strain measurement. I used the same chamber reamer with both as back to back projects. Some of this data was present on "share your favorite load" forum but may have been removed.
I have had the best velocities with the PACNOR barrel.

132gr Lost River Ballistic J40 solid(high start pressure)
61gr. Retumbo 66000psi 3100fps case stuck badly

120gr Nosler ballistic tip
H1000 62gr. 65000psi 3340fps best accuracy .4-.5"
60gr. 61000psi 3260fps

108gr. Lapua VLD
Retumbo 69gr. 60000psi about 3600fps .6"
H4831SC 61gr. 65000psi 3640fps

100gr Nosler Ballistic tip
Retumbo 72gr 65000psi ?(suspect around 3700fps)
.6"
95gr. Hornady VMAX
H4831SC 64gr. 64000psi 3787fps bullets broke up
65gr. 66000psi 3826fps bullets broke up

In Contrast with the Douglas barrel measured with the same equipment:

95gr Hornady Vmax
H4831SC 69gr. 65000psi 3600fps

120gr. Nosler Ballistic Tip
H1000 69gr. 65000psi 3250fps

Cases in both rifles need full length resizing every round despite working pressure and tend to stick early compared to longer cases. This case clearly has the best ballistic advantage with smaller bullets. Therefore, most of our work has been done with the lighter VLD type bullets.