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Seating Stem Marks Explained
Every reloader eventually finds a mark on a bullet after seating, and not all of those marks mean the same thing. This article explains why seating stems leave impressions at all, which marks are purely cosmetic, and which ones will cost you accuracy downrange. Whether you're loading match bullets or hunting soft points, two quick tests will tell you when to shoot a round and when to pull it.
Troubleshooting
RCBS Editorial Team

Seating your bullet is the final step in reloading. One common question about bullet seating is the impressions, dents or blemishes left on a bullet after it is fully seated. If you’ve noticed a mark on the tip or ogive of your bullet, you might be wondering “Was my bullet seated correctly?” and if the mark is severe enough, “Does this mark affect my bullet’s performance down range?” or even “Do I need a custom seating stem to load these bullets?”

These are the right questions to ask, because the answer is not the same for every mark. Some of what you see is cosmetic. But some marking can give you a reason to pull the bullet and start over.

Four rifle bullets side by side showing four different nose profiles: a polymer tipped bullet, a metal tipped match bullet, a soft point, and an open tip hollow point.
Four bullets, four nose profiles — and four different answers to the question of whether a seating stem will mark them.

Why Does the Seating Stem Mark a Bullet at All?

An RCBS seater plug showing its threaded body and the hollow cavity at the tip that contacts the bullet nose.
The cavity inside the seater plug is a fixed profile. When it does not mirror the bullet’s nose, seating force pinches one narrow band instead of spreading across the ogive.

A seating stem or plug is the internal, semi-hollow metal rod built into the interior of your seating reloading die. It works by pushing on the bullet’s nose as it drives the bullet down into your charged case. The cavity inside that stem is a fixed profile and dimension. So is your bullet. When the two profiles do not agree, the seating force from your die concentrates on a narrow band of contact instead of spreading across the ogive.

Add a thin jacket, an exposed lead tip, a polymer tip or a long secant nose, and that concentrated contact leaves a mark. Nothing is broken — the geometry simply does not match.

What Marks are Okay – And What Marks May Impact Performance

In general, thin, light marks on your bullet’s ogive after seating will not impact your performance when that reloaded round is fired. Severe impressions, deep, dented rings, or any scoring left by a seating stem will affect your bullet’s performance. These rounds shouldn’t be fired as they can cause ballistic and pressure issues along with erratic bullet flight.

Here is why: a deep ring is displaced jacket material. Once material moves, the ogive is no longer symmetrical, the bullet no longer engages the rifling evenly, and its balance shifts off axis. Downrange, that shows up as unexplained fliers and inconsistent velocity.

Three damaged bullets: a tipped match bullet with a defined ring, a soft point with a dented band, and an open tip bullet with a ring and a swaged mouth.
Left to right: a defined ring on a tipped match bullet, a dented band on a soft point, and a ring plus a swaged mouth on an open-tip design. All three bullets are likely unusable.

What About Scuff Marks and Blemishes?

A red polymer tipped bullet showing light scuffing and burnish marks on the ogive left by a properly fitted seating stem.
Light scuffing and burnish marks from a properly fitted stem. Nothing has moved — load it and shoot it!

A blemish or slight scuff mark from a properly fitted seating stem may not look 100% perfect coming off your reloading press, but odds are these bullets will fly as intended, reliably. Nothing has been displaced — the jacket surface is touched but not moved or cut.

RCBS’s team has loaded scuffed and lightly blemished bullets from our favorite lots and tested them well past 1,000 yards with no effect on group size or point of impact.

How Do I Tell the Difference?

Test 01

The Fingernail Test

Run a fingernail across the mark. If you catch an edge — a step you can actually feel — material has moved and you have a ring or a dent that may impact your bullet’s performance. If the mark is smooth and only shows when you tilt the bullet in the light, it is a blemish.

Test 02

The Caliper Test

Put an RCBS caliper across the marked band and compare it against an unloaded bullet from the same box. Anything you can measure is a dent. Anything you cannot measure is cosmetic.

What if I’m Constantly Marking Bullets? Do I Need a Different Seating Die?

A seating stem should match the bullet you are loading. When the stem cavity mirrors the nose, seating force spreads across the ogive instead of pinching one band of it, and any serious marks beyond the minor and cosmetic stop.

That is why modern RCBS seater dies use stem profiles cut for the bullets people load today — long, high-efficiency VLD and hybrid ogives that older seating stem geometry was never designed to contact correctly. Older dies from RCBS with original stems were not necessarily designed with today’s high efficiency, high BC bullets in mind. RCBS designs each of our seating dies and stems for the specific cartridge. For example, we design and manufacture our stems for longer, match-ready bullets for cartridges like 6mm Creedmoor popular for match shooting, while the stem design for cartridges like 45-70 Government or 30-30 Winchester will be designed for very different bullets.

Ever had a bullet get stuck in your seating stem? Was a bullet wedged into your plug?

That may be a sign of a mismatch between your bullet and stem’s profiles. This usually occurs when loading a modern bullet into an older die set or seating stem that was not made for a modern projectile’s profile.

If you are consistently and seriously marking bullets beyond the cosmetic, RCBS recommends picking up a modern seating die to fix most of your issues. If you are still experiencing problems, contact our support team anytime.

Precisioneered Reloading

Match the Stem to the Bullet

Caliber-specific seater plugs let you fit the stem to the nose profile you are actually loading — so seating force spreads across the ogive instead of pinching one band of it.

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