.38 S&W in a .38 Sp.HD gun

I would be reluctant to load .38 S&W brass heavier than factory loads. Shorter cases when stuffed full of powder (such as 9mm) operate at chamber pressures about twice that of standard pressure .38 Special. So, you cannot safely use 9mm or .38 Super data as a guide, because you have no idea what the pressure and velocity will be, or if the round would be safe and accurate when firing a short round resulting in greater bullet jump when fired in the standard chamber.

While it is logical to think that chamber pressure would be reduced by firing a short round in a longer chamber, because a poor gas seal would result by firing an unsupported .358 bullet down the length of a longer .38 Special or .357 chamber, this is not always true. When I was at Ruger we did some testing with a short rimmed round called the 9mm Federal, which was essentially a rimmed 9mm Parabellum for use in revolvers without the clip. At that time the company was also building 9mm revolvers for the French police, and .380/200 British revolvers for India, as well with experimenting with a hybrid chamber for a government customer who wanted the ability to use 9mm Parabellum, 9mm Largo or .38 Super, with clips, or .38 Special +P without the clips.

This pipe dream did not work out, because when using fast-burning powders with soft bullets, including most JHP designs for 9mm, the bullet base may upset to conform to the .379” diameter chamber mouth, resulting in a steep pressure rise of over 10,000 psi as the upset bullet base had to squeeze down again as it transitioned into the smaller diameter ball seat in the front end of the cylinder. While the result was not dangerous when firing lower powered ammunition such as .38 S&W or .380/200 British, it was more interesting with 9mm Parabellum, 9mm Federal, and .38 Super.

So my advice is NOT to load short rounds for your .38 or .357 unless you either stick to .38 Long Colt or .38 S&W pressure levels not to exceed about 14,000 psi, or you have access to pressure test equipment or lab tested data to ensure that there are no unpleasant surprises.

Instead, it is better to load full-charge .38 Special wadcuttter ammo which uses its case length effectively. For revolver use seat out wadcutter bullets, instead of flush seating, as is normally done for factory target loads which must fit into target auto pistol magazines.

I seat my Saeco #348s out so that its front band or bevel is outside the case mouth. This gives better bullet alignment which aids accuracy than flush seated, in most cases. I load these as-cast and unsized, tumbled in Lee Liquid Alox. As-cast bullet diameter is .360", we use the Lee Factory Crimp die in the final die station on the Dillon machine so all rounds are full-length profiled, and bullets are sized by compression inside the case, rather than by shear in a die.

Best accuracy is obtained with thin mouthed “wadcutter” brass, originally used for factory target loads, because these result in less bullet deformation, but ordinary service load brass can be used, with slight loss of accuracy which won't be noticed at ranges less than 50 yards. Crimp Remington HBWC component bullets no more than needed to remove mouth flare. Harder cast bevel-based or DEWC bullets may be roll crimped in their crimp groove, if the bullet has one.

Bullet seating depth must be adjusted so that all rounds chamber fully without resistance, which might cause rounds to drag against the recoil shield, causing hard cylinder rotation in DA firing. The Saeco #348 double-end bevel base when crimped in its crimp groove fits standard .38 chambers and ensures perfect alignment. The exposed band with slight base chamfer aids reloading when using speed loaders. Our Dillon machine is adjusted to give 1.225” OAL with the Saeco #348, which chambers freely in a variety of Colt, Ruger and S&W revolvers. The double-end, bevel base design can be loaded with the sprue-cut forward, so that you always have a perfect base for best accuracy.

For “standard pressure” .38 Special full charge wadcutter loads with cast DEWC bullets which approximate the velocity and energy of the old 158-grain RN service load, safely useable in any sound .38 Special revolver - including light alloy frames such as the S&W Airweight or Colt Agent and Cobra, load 3.5 grs. of Bullseye, 4.2 grs. of W231 or 4.5 grs. of Unique with either a double-end cast wadcutter such as the Saeco #348, or swaged bevel -based wadcutters from Speer, etc.

Cast bullets may be as soft as 8 BHN or 1:25 tin/lead or 50-50 plumbers lead and wheelweight with only enough tin added, about 1%, to get good fillout. Velocity will be about 850 f.p.s. in a 4 inch revolver and approach 900 in a 6 incher. A very useful general-purpose load. Your mileage may vary.