July 27, 2021
Polish the Inside of Seating Stems to Avoid Bullet Rings
Here’s a tip for hand-loaders using Sierra Bullets. Although this article is focused on Sierra’s Tipped Match-King Bullets, the recommendations can be applied to all bullet types. This article describes how sharp edges can cause a ring of pressure to form in the bullet jacket, especially when compressed loads resist downward bullet movement. Rich Machholz, a Sierra technician, diagnoses the problem. He also offers a solution.
Solutions for Ring Marks caused by Seating Stems
Rich Machholz, Sierra Bullets Ballistic Technician
One of several factors can be blamed for the problem. The.223 and particularly the long, 77 grain, TMK seated at 2.250″, or even 2.260″, most loads of Varget(R), and Reloder(R), 15 are compressed loads. This places a lot of pressure on the bullet through its seating stem. All this pressure results in a mark with varying depths and appearances on the bullet’s ogive. [Editor] We have seen this issue with many other bullet types/shapes, including non-tipped VLDs. Profiling the inner cone of the seating stem is the solution to match your bullet shape.
Older seating stems may even be pressed against the bullet’s tip, which can cause a slight bulge to the jacket below the junction between the resin tip or the copper jacket when the load is compressed. If this happens, there is no quick fix except to call the die manufacturer and request a new deeper seating root.
Polish your Seating Stem to Remove Sharp Inner Edges
If the seating stem has the proper depth, the problem is usually a thin sharp edge at the inside of the seating stem. This can be fixed by simply chucking in a spare 77 grain bullet and coating it with valve grinding compound, rubbing compound, or in a pinch, tooth paste. * Take the seating stem assembly out of the seating die. Turn the drill on, and place the seating stem recess above the spinning bullet. Use the polishing compound for to smooth out the sharp edges. It may take several applications to achieve the right polish, depending on the polish you use. However, the more angles you polish, the better the blend. This will ensure that the stem matches bullet contours and not leave a sharp ring.
If you find the above a bit too much, you might consider using very fine emerycloth. This can be twisted to a point where it can be inserted into your seating stem. Rotating the cloth will polish the inside and remove any sharp edges.
Load Advice for 77grTMKs in.223 Rem
Last but not least. Even though we don’t think you need additional data to use the TMKs in certain cases, you will be dealing with compressed loads in some cases due to the increased bullet length. In order to gain some space in your case, you might consider using a faster extruded powder such as the 4895s or BenchMark. You will have trouble-free bullet seating thanks to the extra space.
Good luck! Remember to dial 1-800-223-8799 for assistance.
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Tags: bullet, Rich Macholz, Seating Stem, Sierra Bullets, TMK
