As you know, forming the neck, shoulder and taper of the cartridge case is a process that is done after drawing the straight walled brass of proper diameter and length. Starline now offers .223 Remington brass that hasn’t passed the neck and shoulder forming process. It is basically a straight walled case of .378 diameter and 1.8″ length. They call it .223 Un-Tapered brass.

Note the headstamp of these cases with only “stars and lines” and no caliber stamped.

Starline’s target market for this half-made brass are the wildcatters. This brass comes with no caliber designations on the case head. The Un-Tapered brass is also not annealed and will require annealing before forming into any wildcat caliber. The neck and shoulder area may also need to be annealed after forming. The case wall thickness at the case mouth is .009. The neck thickness of formed cases will increase as a result of necking down the brass. These cases also have small rifle primer pockets.

.357 AR is a good example of a wildcat cartridge that can be formed using the straight walled brass. Image from GBO Forums

Here is also an important statement made by the manufacturer:

Since this is a basic case, and Starline has no control over how it is formed, we accept no liability and offer no warranty in its use or your inability to properly form cases. Since this case has not been formed there may be more out-of-round mouths than normal.

According to Starline, these cases are suitable for forming many .223 Remington based cartridges such as the TCU family of cartridges (6mm TCU, .25 TCU 6.5mm TCU, 7mm TCU and .30 TCU), 6x45mm, .25-45 Sharps, 6mm Mongoose, 7.62x40WT, 7Raptor and .357 MAX AR. Of course, there are many other cartridges that are based on a .378 diameter case and can be formed using the Starline Un-Tapered brass.

The Starline Un-Tapered brass is available on the company’s website at $90 per pack of 250 cases.