Shooting Area 103 sq in
Active Area 84 sq in
Beam Width 30 degrees
Beam Thickness
(6 inches above unit)
0.1 inch


Minimum spacing of 1 foot is allowed; minimum spacing of 2 feet is recommended. Spacing of 4 feet is suggested for high velocity rifles. Spacing of primary screens can be set from 1 to 15 feet; proof screen is always set midway between primary screens. Careful measurement of the distance between the screens is required. A 1/8″ error in screen spacing is enough to cause errors in the velocity measurements.


The built-in printer prints with real ink on standard 2.25 inch plain paper. It prints primary velocity, round number, and proof velocity as each round is fired. It prints statistical summary of primary velocity.


0° to 50° Centigrade, 32° to 122° Fahrenheit.
Systems typically operate at temperatures down to 0°F or -18°C.


An edit mode allows for instant replay of up to twenty shots. During replay you can omit questioned shots from the summary.


A single nine-volt NEDA 1604 alkaline battery is supplied. A fresh battery will operate the system for up to 25 hours including 1000 print lines. Internal battery compartment includes space for spare battery.


4.0 MHz oscillator for 0.25 microsecond time resolution


The expected error on any one shot depends on both velocity and screen spacing. Typical errors are shown in the table. The table assumes good light conditions, dark bullets, exact screen spacing, and shooting through the center of the Skyscreen III window. Actual errors under your shooting conditions will be reliably indicated by the PROOF CHANNEL

1 FT 2 FT 4 FT 8 FT
1000 FPS 5 fps 3 fps 1 fps 1 fps
2000 FPS 10 fps 5 fps 3 fps 2 fps
3000 FPS 16 fps 8 fps 4 fps 2 fps
4000 FPS 21 fps 10 fps 5 fps 3 fps

You will typically see the above errors as differences between the primary and proof channels of a Model 35P as you shoot under “normal” conditions.

Note: It’s easy to claim fantastic accuracy with a chronograph measuring only one velocity. Who checks the claims? You know your accuracy only with the PROOF CHANNEL, or by using two chronographs on each shot. We know our chronographs are more accurate and more reliable, so we invite you to check each shot.


The system alerts you with a flashing display and printed asterisk if there is a significant difference between the two velocity readings. Differences which trigger the alert are shown for typical velocities and screen spacings.

1 FT 2 FT 4 FT 8 FT
1000 FPS 42 fps 21 fps 10 fps 5 fps
2000 FPS 83 fps 42 fps 21 fps 10 fps
3000 FPS 125 fps 63 fps 31 fps 16 fps
4000 FPS 166 fps 83 fps 42 fps 21 fps


Professional statisticians have long preferred standard deviation as the best measure of uniformity. We admit, standard deviation is a dog to compute. That’s why Oehler chronographs compute it automatically.

Before calculators and computers were common, people used substitutes for standard deviation. One substitute is extreme spread or the difference between fastest and slowest shots. Our chronographs include extreme spread because shooters expect it.

Lately a second substitute, mean absolute deviation, has been resurrected. One manufacturer promotes MAD as a new discovery and a miracle answer to measuring velocity uniformity. Like comparing chopped steak to sirloin, mean absolute deviation gets you by, but it’s not as good as standard deviation. Don’t take our word for it; ask any statistician or check an elementary statistics text.


Short endorsements quoted in advertisements can be misleading. Beginning in 1967, Oehler systems have become the official chronographs of uncounted competitions and laboratories. Most of the commercial and military ammo made in the U. S. during the last twenty years was checked with Oehler systems before it left the factory. The U.S. arsenal loading military small-arms ammo uses ten Oehler System 82 units in the proof house, and they use a Model 35P to verify the set-ups of the large systems. Regular use by those who recognize the best is the truest endorsement!

PROOF CHANNEL without printer?

The PROOF CHANNEL is in every Model 35 chronograph; you just need to use a third skyscreen. If the PROOF CHANNEL determines that a reading is suspect, the display flashes off and on. You know immediately that the reading should not be taken too seriously. Even without a printer you know if an error was likely.


The Model 35 comes with a 30 page instruction book expanding on these condensed instructions. It’s simple to use.

  • Mount the two primary skyscreens at the ends of the rail with the proof skyscreen at the middle.
  • Place the skyscreens approximately 10′ in front of the gun. Position so that a shot aimed at the target will pass through the center of the skyscreen windows.
  • Plug Skyscreen cables into the M35. Plugging in the start cable turns on the system. Push reset button until you see – – – 0 on the display.
  • Fire through skyscreen windows. The shot number and then primary velocity will be displayed. (The M35P automatically prints proof velocity, shot number, and primary velocity.)
  • If the PROOF CHANNEL detects an error, the display flashes and an asterisk is printed. Use the OMIT button to erase any velocity that you suspect is incorrect. Fire additional shots as desired.
  • You may use the EDIT and STEP buttons to replay the entire shot string. You may OMIT undesired readings as you replay the shots.
  • Push the SUMMARY button to summarize the group. Display and printer will show high, low, extreme spread, average or mean, and standard deviation for primary channel.
  • Fire more shots to add to the same group, or push the RESET button to start a new group.