IMR Classic
IMR PB
A shotshell and handgun target powder. The PB designation refers to its porous-base kernel structure.
Discontinued, but it had a real following among light-target shotshell loaders before it went. PB refers to the porous-base kernel structure, and the powder was known for burning cleanly at low target-load pressures; it also served light .45 ACP and .38 Special target work. There is no current data support for it, so anything you load must come from archived manufacturer material.
- light 12 gauge target loads
- 20 gauge target loads
- .45 ACP target
Who has IMR PB today
Checked October 10None of the retailers we track list IMR PB right now. See what is in stock.
Discontinued. Canisters still circulate, but the maker no longer produces it — and load data for it may be withdrawn or archived.
Specifications
| Manufacturer | IMR |
|---|---|
| Product family | IMR Classic |
| Status | Discontinued |
| Application | shotshell, pistol |
| Grain form | extruded |
| Lee VMD (bulk density) | 0.1205 cc per grain · 0.54 g/cc |
| Composition | single-base |
| Typical cartridges | 12 Gauge, 20 Gauge, 28 Gauge, 45 ACP |
Grain shape
Small porous extruded kernels rather than a flake. Porosity raises effective burning surface for the grain size, which is how a physically small extruded grain gets to shotshell burn speed, and the small size lets it meter acceptably by volume.
Why geometry decides burn rate more than chemistry does: Shape Is the Product.
Discontinued. Hodgdon no longer lists this powder among current IMR products and it does not appear on Hodgdon's current relative burn rate chart. It was long favoured for light target shotshell loads. No manufacturer product page remains.
This powder is obscure enough in the US that its practical character is thinly documented. The note above is deliberately short rather than padded.
Data confidence
We flag entries we could not fully verify rather than presenting them as solid:
- Discontinued — no live manufacturer product page; details drawn from archived or secondary manufacturer material.
Sources
The specifications above come from IMR's own published documentation, linked below. The two “RCM's read” sections are ours, not theirs — our assessment of what this powder is like to load, drawn from its published characteristics and from what handloaders consistently report. No manufacturer endorses them and no source below backs them. If you think we have one wrong, tell us — we would rather fix it.