Evening All,
I want to let you all know I had a fun couple hours at the bench today and hopefully what I did is correct. Please correct me if I'm wrong. I went over my Lyman, Speer, and Lee manuals. I proceeded to go get my Starrett dial calipers, hole gages, thickness gages, and 0-1" outside micrometer from the garage.
Following the previous, I then rechecked the burn rates of the powders on hand and decided on some Trail Boss for some powder puff loads for my 66-2 in the 4" variety. I went through the Hodgdon load data for 38 Special and 357 Magnum online and double checked the powder throws on the Auto Drum and PPM on the bench. All the weights showed accurate on the M5 scale at 5.0 grains after some VMD calculations for the CC/grains. I did have about 200 throws through each powder measure since they're new and I understand that the "graphite" property of powders helps lubricate the drops. I measured 90% of the throws.
The batch of 10 produced tonight were after inert cases with the projectiles were assembled, measured, and final adjustments were made. I came up with an average of 1.5625 COAL at final assembly of said rounds with a variance of +0.0026". Final batch recipe based on upper end of 38 Special per manufacturer. Please know that I did fill an empty 357 case and average was 8.8 grains total fill. I did use the 70% methodology to get 5.53 grains, correct me if I'm wrong it's what I wrote down and I did check the math. 5.3 grains is maximum for a 38 case with a SPP and the difference with the 357 case and the data is it calls out the same range starting at 3.0gn and stop at 5.3gn, but with a SPM.
Furthermore, on the calculation of case fill, I did measure 50 projectiles for the average baseand top of cannelure, as well as the length & diameter of each to arrive at seating depth and crimp formation. The process was completed on a Lee Classic Turret press with the 3-die Carbide set and Lee Auto Drum. (I'm going to get another seat/crimp die or crimp die to separate the process for consistency and eliminate the resizing ring.... TBD.)
Here's the recipe, range test this week.
- Winchester 357 case
- Xtreme plated 125gn FNWC
- Winchester Small Pistol Primer (seated .0025")
- 5.0gn Trail Boss
COAL- 1.5625" Avg.
Any input is greatly appreciated. Worth noting that I did pull the projectiles from the cases with an inertia puller to make sure plating was not damaged. There was no damage but chafing of the copper from the tension/crimp on the casing. I hope the crimp is satisfactory since I didn't trim the cases at all.
