Oehler Model 35P
Definition
A dual-screen optical chronograph (plus proof channel) widely used in US forensic and manufacturer testing. Accurate to within 0.2% of reading. The standard instrument for SAAMI test-fire velocity data collection in many US laboratories.
- Type
- Dual-screen optical chronograph with proof channel
- Accuracy
- Within 0.2% of reading
- Primary use
- SAAMI test-fire muzzle velocity data collection
- Manufacturer
- Oehler Research
Common questions
Why does the proof channel matter in ballistics testing?+
The proof channel gives a second, independent timing check alongside the main sky screens, catching false triggers from light flicker or debris that would otherwise corrupt a single velocity reading in a test string.
How is chronograph output used in a forensic case?+
Measured muzzle velocities feed internal ballistics models that estimate a bullet's energy and trajectory, which investigators compare against wound characteristics or reported shooting distances rather than relying on manufacturer nominal figures.
Related terms
- Greenhill Formula
- Alfred Greenhill's 1879 empirical formula for the minimum barrel-twist rate to gyroscopically stabilise a bullet of given length and calibre. Uses a...
- Heydenreich Model
- A parameterised internal-ballistic model incorporating propellant specific force, burn-rate coefficients, and chamber volume. More physically grounded than Le Duc; the conceptual ancestor...
- IBHVG2
- Interior Ballistics of High Velocity Guns version 2; a US Army Research Laboratory code implementing the Lagrange pressure-gradient model for large-calibre and...
- LabRadar
- A Doppler radar chronograph measuring bullet velocity continuously from muzzle to several hundred metres, producing a velocity-distance profile. No physical contact with...
- Le Duc Model
- An empirical algebraic formula (1873) relating muzzle velocity to peak chamber pressure via two calibration constants. Produces velocity estimates within 3-5% of...
- Miller Stability Formula
- A dimensionless stability factor (Sg) formulation published by Donald Miller in 2005, calibrated for modern spitzer bullets. Sg greater than or equal...
- PRODAS
- Projectile / Rocket Design and Analysis System; a US Army Research Laboratory / Arrow Tech Associates lumped-parameter code integrating internal, external, and...