I am a huge fan of the 38 Special cartridge and have accumulated allot of reloading equipment, looking for the best way to load the ammo. I want great accuracy and long case life. The long case life is particularly important with wadcutter brass, which is not easy to come by anymore.
Here are some specs on case resizing dies I found in my notes and through I would pass them along. I used Lake City 78 38 Special brass for the comparison.
I measured the resized cases at the base, the mid-point, the case mouth and the ID of the case mouth. I used RCBS carbide die (R1), a 1958 RCBS steel die (R2) and a Lyman Tru-line Jr. full length die (L) of undetermined age.
Base: R1 - .377, R2 - .3775, L - .379
Mid-case: R1 -.372, R2 - .3765, L - .377
Mouth: R1 - .371 , R2 - 371, L - .376
Mouth ID; R1 - .351, R2 - .351, L - .356
A look at these numbers tell me R1 and R1 produce identical case mouth specs. However the R1 (carbide) sized the case the same as the mouth all the way down to near the base.
The Lyman produces a case larger at the mouth, the mid-point and base. Cases sized with this Lyman die still chamber freely in the dozen Smith and Wesson and Colt revolvers in my safe.
The Lyman die requires less case mouth expansion to seat the bullets.
With the current lot of R-P wadcutter brass I am using the outside numbers are the same, but the ID of the case mouth is .358. This means I only need a slight bell to seat .358 - .359 cast bullets. I use a light taper crimp to keep these bullet in place.
There is no such thing as "everlasting" brass cases, but case life can be greatly extended by working the brass less. The less the better. I also hold that rounds that fit the cylinder charge holes with less slop will introduce the bullet into the cylinder throat straighter for better accuracy.
For ordinary cases like the LC 78, I use the RCBS steel die, but for the precious wadcutter brass I use the Lyman Tru-Line Jr. FL die.
I have older steel steel dies by Pacific, CH, and Lyman Shell Resizer and their dimension are not significantly different from the steel RCBS die. The Lyman Tru-Line Jr. seems to be the outlier in this regard.
I have a Redding Turret press set up for just 38 Special use, and both the Lyman TL Jr and the steel RCBS are installed in the turret.
For the 45 ACP, I use my RCBS carbide die as there is not significant different in the finish dimensions from the various steel dies in my collection.
For the 44 Special and Magnum, I use steel dies as there is a significant difference in the finish dimensions from the carbide dies.
For the 45 Colt, I use steel dies and again there is a significant difference in the finished dimensions from the carbide dies.
For those reloaders who consider not having to lubricate cases more important than case life, none of the above is significant to you.