Test results
Prototype range test report for the Borechill barrel cooling jacket. Primary session: November 8, 2026 (Prototype #2, 60-shot string). Report status: preliminary.
Summary
November 8, 2026: 60 counted rounds (after one uncounted sighter) through a Savage Model 12 F/TR .308 with a stainless full-profile barrel, Borechill Prototype #2 jacket running. Four-channel K-type thermometer at UF, UR, LF, and LR. Live readings are barrel–bladder interface temperatures, not independently validated bare-steel barrel temperatures. No cooling-percentage claims are made from this data.
Garmin Xero: 60 shots, average 2,896.0 fps. Accusplit stopwatch at the final shot: about 11 min 45 s, including lead-in before the first counted shot.
Videos
Full test — regular speed
Live instrument-camera inset: thermometer, Accusplit stopwatch, and shot count.
8× speed timelapse
Same session at 8×, with the instrument inset.
Test setup
Savage Model 12 F/TR .308, stainless full-profile 30 in barrel, 1:10 twist, Vortex riflescope, no suppressor. Sierra .308 Win 165 gr SBT GameKing, lot A2145-01 (box spec 2,760 fps muzzle; G1 BC .404). Fired from a bench (bipod front, sandbag rear) in Marble Falls, Texas, with the pump running.
Prototype #2: cooling jacket on the barrel; 12V submersible pump in a portable ammo-can cooler with about 1 gallon of water and 2 large ice packs (starting water temperature not recorded). A 12V supply powered the pump for 23.5 hours in an overnight run test. Early hand-built prototype, not a production unit.
Instruments: YZT Meter four-channel K-type thermometer — UF (T1), UR (T2), LF (T3), LR (T4). UR was right over the chamber; LR about 3 in forward of it, just outside the stock; UF and LF about 4 in from the muzzle end of the barrel. Accusplit Pro Survivor 601X stopwatch. Garmin Xero chronograph (RIFLE mode). WeatherFlow meter, 2026-11-08 ~10:55 AM CT. Instrument-camera coverage begins at about stopwatch 4:19 (about counted shot 19). Counted shots 1–18 have no instrument-camera temperature coverage.
Conditions at the bench: 69.6 °F, 63% relative humidity, wind 0.0 mph (direction 21°), 29.11 inHg, density altitude 1,840 ft, dewpoint 56.5 °F. Setup photo EXIF 11:16 AM CT; weather screenshot ~10:55 AM CT. Exact first-shot clock time not recorded.
Pace: stopwatch at the final counted shot about 11:45 (includes lead-in; exact firing-only duration is not separately verified). During the instrument-covered portion (counted shots ~19–60), typical inter-shot intervals were ~8–12 seconds (median about 8 s among intervals under 30 s). One pause of about 57 seconds between counted shots 37 and 38.
Results (measured) — November 8, 2026
Barrel–bladder interface temperatures (°F), sampled from instrument-camera frames at the listed shot / stopwatch points (visual read of the YZT LCD). No correction factor is applied.
Sampled interface temperatures during the string
| Counted shot | Approx. Accusplit | UF (T1) °F | UR (T2) °F | LF (T3) °F | LR (T4) °F |
|---|---|---|---|---|---|
| (instrument start, before shot 19) | ~4:19 | 71.5 | 85.1 | 73.3 | 61.3 |
| 19 | ~4:47 | 70.3 | 83.3 | 72.0 | 61.2 |
| 26 | ~5:46 | 75.2 | 86.0 | 76.9 | 61.3 |
| 30 | ~6:21 | 79.5 | 90.6 | 81.7 | 61.6 |
| 32 | ~6:40 | 81.8 | 93.9 | 84.2 | 61.9 |
| 38 | ~7:28 | 86.8 | 102.1 | 89.9 | 62.4 |
| 46 | ~9:25 | 88.9 | 108.8 | 92.7 | 63.5 |
| 51 | ~10:10 | 93.6 | 115.5 | 98.3 | 64.2 |
| 56 | ~10:58 | 95.1 | 119.6 | 100.2 | 64.9 |
| 60 (near last) | ~11:38 | 97.2 | 124.6 | 102.7 | 65.6 |
| 60 (at final shot) | ~11:45 | 97.8 | 125.8 | 103.8 | 65.7 |
Counted shots 1–18: interface temperatures not available (no instrument-camera coverage).
Chronograph summary (Garmin Xero)
| Metric | Value |
|---|---|
| Shots | 60 |
| Average | 2,896.0 fps |
| Minimum | 2,870.0 fps |
| Maximum | 2,941.4 fps |
Last on-screen reading: 2,889.4 fps.
Summary of measured results
From about shot 19 through shot 60:
- UR (T2) was the hottest tagged channel. It read 85.1 °F at instrument start, 83.3 °F at shot 19, and 125.8 °F at the final shot (~11:45 on the Accusplit).
- UF (T1) read 71.5 °F at instrument start, 70.3 °F at shot 19, and 97.8 °F at the final shot.
- LF (T3) tracked between UF and UR and ended at 103.8 °F.
- LR (T4) stayed much cooler, moving from 61.3 °F to 65.7 °F.
- Temperatures continued to climb through the 60-shot string on UF, UR, and LF.
These are interface readings only. Without a matched uncooled control run and without independently validated bare-steel measurements at the same locations, cooling effect is not quantified here.
Results are from a single early prototype and are preliminary.