On July 17, 2026 we published a market recap reporting that the median seven-day move across 28 tracked calibers was −2.9%, that eight calibers led a broad decline, and that 20 gauge was the lone outlier moving up.
None of those moves describe changes in ammunition prices. They were artifacts of how IronScout measures, and we should not have published them.
This page now carries the correction in place of the original recap.
What we claimed, and what a like-for-like measurement shows
IronScout's observed median pools, for every tracked product with an in-stock listing, the best per-round price seen that day, then takes the median across a rolling 30-day window. That pool spans every retailer eligible in our data at the time — it is not normalized to a stable set of retailers.
Between the two windows this recap compared, retailers were added to the tracked data, and the ones added were cheaper than the incumbents. Adding a cheaper seller to the pool lowers the median with no price changing anywhere.
Re-measuring the identical window using only the product-and-retailer combinations observed at both ends — the same items at the same sellers:
| Caliber | We reported (7-day) | Like-for-like (7-day) | Matched pairs |
|---|---|---|---|
| 9mm | −16.6% | 0.0% | 929 |
| .380 ACP | −15.5% | 0.0% | 223 |
| .223/5.56 | −13.9% | 0.0% | 948 |
| .38 Special | −13.0% | 0.0% | 311 |
| .32 ACP | −9.0% | 0.0% | 63 |
| .45 ACP | −8.7% | 0.0% | 464 |
| .40 S&W | −7.9% | 0.0% | 507 |
| .300 Blackout | −5.7% | 0.0% | 290 |
| 7.62x39 | −0.2% | 0.0% | 138 |
| 20 gauge | +4.0% | 0.0% | 328 |
Every caliber the original recap named, in both directions, was flat when measured against a stable basket.
The "broad decline" and the "outlier that moved against it" were the same artifact, pointing in different directions depending on which retailers happened to enter each caliber's pool that week.
The thirty-day column in the original table was affected more severely still. Over that longer window the tracked retailer count for most calibers roughly doubled.
The reasoning that should have caught it
The original recap argued that rising in-stock counts corroborated the declines — that the shelves getting deeper was evidence cheaper products were coming back into the observed mix.
That was the error. Those counts did not rise because shelves refilled. They rose because we added retailers. We cited the cause of the artifact as evidence that the artifact was real, and then pointed readers to a companion 9mm post that made the same mistake in more detail.
Why our tooling did not stop it
IronScout's signal engine already emits a basket-shift caution when the tracked retailer count moves more than 20% between compared snapshots. It fired. It went into an internal editorial digest, and nothing required the published copy to carry it.
That gap is now closed by a build-time guard: any post asserting a period-over-period move in an observed median fails the build unless it also discloses that the tracked retailer basket can change between the compared windows. On the live surfaces an affected comparison is now suppressed rather than annotated — a caveat attached to a wrong number still publishes the wrong number — and the standard for publishing a comparison over time is written down rather than left to editorial habit.
Those changes detect coverage change from retailer and product counts, which is a proxy. The durable fix is to compute these series on matched baskets by construction, the method that produced the 0.0% column above. That work is not built yet; until it is, the surfaces go quiet on a comparison rather than guess at it.
What this does and does not mean
It does not mean prices rose, and it does not mean our current per-round figures are wrong. What each caliber costs today across the retailers we track was never in question. What was wrong was the comparison across time, because the set being compared changed underneath us.
Growing our retailer coverage makes every current figure more representative. It simply invalidates before-and-after comparisons spanning that growth unless they are measured on a stable basket.
Current per-caliber figures and distribution bands are on the Ammo Price Index. The companion 9mm post has been corrected for the same reason.
Correction published 2026-07-30. Original recap published 2026-07-17. Like-for-like figures re-derived from the underlying observation record, comparing only product-retailer pairs observed in both the July 10 and July 17 thirty-day windows. Observed daily-best per-round medians from tracked online retailers, in stock at observation time; they may not reflect the entire market. Market context only — not a recommendation.