Chronograph

Match Chronograph and Equipment Set-Up

Chronograph(s):

1. The chronograph(s) must be shielded from the effects of changing sunlight. Setting the chronograph(s) in the shade of a tree, or under a cover which allows a differing amount of sunlight to touch any part of the skyscreens or skyscreen brackets is prohibited. The recommended method for outdoor locations is to use an enclosed “chrono box”. In all locations, the use of either infrared sensors or incandescent lighting provides the most consistent, repeatable results. USPSA does not require a specific brand or type of chronograph. Radar sensing units are acceptable, provided they are set up and operated according to the manufacturer’s directions for use and verified daily using the procedure outlined in section 17.
2. Two chronographs should be used when possible and set up in tandem so both units measure each shot fired.
3. In all cases, the skyscreens must be positioned and spaced per the manufacturer’s requirements for the chronograph in use. The closest skyscreen must be placed no less than 10 feet from the shooting location (measured from muzzle of firearm to skyscreen). When radar sensing units are used, the reading at V0 must be used. If the unit only displays a single reading it will be used as the muzzle velocity.
4. When possible, the chronograph(s) should be run on AC power. If using generator power, the chronograph readings must be monitored for consistency. If using battery power, the battery must be changed or recharged as necessary to insure consistent results.
5. Failing these conditions, or in the absence of a chronograph, the match must use each competitor’s declared Power Factor for match scoring.

Scale(s):

6. Scales must be shielded from the wind to prevent errors in measurement while weighing competitor bullets.
7. Two scales are recommended when available, weighing each bullet tested on both scales.
8. Whenever possible, the scale(s) should be run on AC power. If using generator power, the scale readings must be monitored for consistency. If using battery power, the batteries must be changed or recharged as necessary to insure consistent results.
9. A set of appropriate check weights must be used in calibrating the scale(s).
10. Failing these conditions, or if a scale is not available, each competitor’s declared bullet weight must be used.
11. If a division as listed in Appendix D requires weighing of a firearm, the same procedure as above will be followed.

Bullet Puller(s):

12. Bullet pullers must be of a design which will not damage the bullet or change its weight.
13. If a bullet puller is not available or breaks and a replacement is not available, the declared bullet weight must be used for all subsequent competitors.

Calibration Ammunition:

14. A sufficient supply of match calibration ammunition must be available and used to calibrate steel targets and (when necessary) verify the match chronograph.
15. To assure consistency, the match calibration ammunition should be comprised of ammunition from the same lot. 9x19 mm is the recommended caliber.
16. The ammunition, as fired through each designated firearm, should achieve a power factor between 115.0 and 125.0.

Match Chronograph Daily Verification

Chronograph(s):

17. Prior to performing any competitor ammunition testing, the Chrono Officer will fire three rounds from the supply of the official match calibration ammunition through the calibration firearm over the chronograph(s) and record the average velocity of the three rounds for each chronograph in use.
18. Dual chronograph configurations are not subject to subsequent daily verification provided that the differential of the velocities between the two chronographs remains reasonably consistent with the differential of the average velocities recorded above.
19. For single chronograph configurations, or whenever one of the dual chronographs fails and cannot be replaced, the single functioning chronograph is subject to subsequent daily verification check. Specifically:

a. On each of the following days, the process specified in Item 17 will be repeated using the same firearm and ammunition supply.

b. The chronograph is deemed to be within tolerance if the daily average is within +/- 4% of the first day’s average.

20. Should a daily variance exceed the allowable tolerance above, the Range Master will take whatever steps necessary to rectify the situation. If more than one chronograph is in use, and only one is out of tolerance, that chronograph can be removed from service and the remaining chronograph can be used alone for the rest of the match.
21. If the Range Master determines that variances or malfunctions make further testing unreliable or impossible, the power factors of competitors who have been successfully tested will stand. The power factors declared by all competitors who have not been tested will be accepted without challenge, subject to any applicable Division requirements.

Scale(s):

22. Daily, prior to weighing any competitor bullets, the Chrono Officer will calibrate each scale using the scale’s supplied calibration weights per the manufacturer’s instructions, following which the scale will be zeroed and a designated check weight(s) will be weighed on each scale and the results recorded.

Daily, prior to weighing any competitor firearm, the Chrono Officer will calibrate each scale using the scale’s supplied calibration weights per the manufacturer’s instructions, following which the scale will be zeroed and a designated check weight(s) will be weighed on each scale and the results recorded.

23. For the duration of the match, a scale is considered to be in tolerance if:

a. the scale is able to maintain a weight display stability of +/- 0.1 grain (0.2 ounces in the case of a firearm scale) over a 15 second period, and b. the scale is able to repeat the results of the recorded weights in Item 22 within +/- 0.1 grain, 0.2 ounces in the case of a firearm scale.

24. A scale suspected or found to be out of tolerance will be reset (calibrated and zeroed) and demonstrate satisfactory tolerance prior to being returned to service. Any competitor suspecting a scale is out of tolerance may request that the Range Master be summoned for a ruling.
25. A scale failing Item 23a must be checked for effective wind protection and stable positioning prior to reset.
26. If it is determined that a scale is unable to remain within tolerance or has failed, it must be removed from use. A replacement scale may be utilized if it can be calibrated, zeroed, and be demonstrated to be in tolerance.
27. If more than one scale is in use, and one has failed, the remaining scale can be used alone for the rest of the match.
28. If the Range Master determines that variances or malfunctions make further weight testing unreliable or impossible, the bullet or gun weights declared by all competitors whose bullets or guns have not been weighed will be accepted without challenge, subject to any applicable Division requirements.

Competitor Ammunition Collection and Storage

29. An initial sample of eight rounds of ammunition will be collected from each competitor at a time and place determined by Match Officials. Match Officials may require that a competitor’s ammunition be retested at any time during the match and may collect further samples as necessary.
30. It is recommended that ammunition be collected from competitors as randomly as is possible to ensure that the collected ammunition accurately matches the ammunition the competitor is actually using in competition.
31. Collected ammunition must be clearly labeled with the competitor’s identity.
32. Collected ammunition must be stored in a shaded location, out of the direct effects of the sun. When stored overnight, collected ammunition must be stored indoors at normal room temperature.

Competitor Ammunition Testing Procedure

33. Ammunition must be tested using the competitor’s firearm. Prior to and/or during testing, the competitor’s firearm and the component parts thereof must not be altered or modified in any way from the condition it is being used (or will be used) at the match. Violations will be subject to Section 10.6.
34. Conventions to be used for all measurements:

a. if more than one chronograph is in use, the highest velocity recorded by any of the chronographs shall be used for each respective shot.

b. if more than one scale is in use concurrently, the highest weight measured by the scales shall be used for each respective bullet weighed.

35. From the eight sample rounds drawn by Match Officials, one bullet is weighed to determine the actual bullet weight and three bullets are fired over the chronograph. Digits displayed on the official match bullet scales and chronograph will be used at face value, irrespective of the number of decimal places indicated on the measuring device used at the match.
36. Power factor is calculated using the bullet weight and the average velocity of the three rounds fired, according to the following formula:

Power Factor = bullet weight (grains) x average velocity (feet per second) / 1000

The final result will ignore all decimal places (e.g. for USPSA purposes, a result of 124.9999 is not 125).

37. If the resultant power factor fails to meet the declared power factor score, another round will be fired over the chronograph and the scores recalculated using the bullet weight and the average top three highest velocities of the number of shots fired. This will continue until either the competitor meets the minimum power factor or until all 6 rounds have been fired.
38. If the power factor is still insufficient, the competitor may elect to have:

a. the final bullet pulled and weighed and, if heavier than the first bullet, the power factor calculation in Paragraph 36 will be recalculated using the heavier bullet weight, or b. the final round fired over the chronograph and the power factor recalculated using the first bullet weight, and the average velocity of the three highest velocity rounds from the seven rounds fired.

39. If the resultant power factor fails to meet the Major power factor floor of the relevant Division, the competitor’s entire match scores will be recalculated as Minor, if achieved.
40. If the resultant power factor fails to meet the minimum power factor floor for the relevant Division, the competitor may continue shooting the match, but not for score or match recognition.
41. Due to the different methods used by certain chronograph brands to calculate Power Factor, any power factor results produced by the Chrono Station chronograph are considered interim results and subject to confirmation.

a. The only official power factor results are produced and/or confirmed by using the formula specified in Item 36 or via the scoring program.

42. If a competitor’s match ammunition is retested, or if any authorized replacement ammunition is used, and different power factors are recorded when tested according to these rules, the lower power factor must be applied to all courses of fire, including those already completed by the competitor.
43. The scores of a competitor who, for any reason, fails to present his firearm for testing at the designated time and location and/or who fails to provide sample rounds for testing whenever requested by a Match Official will be removed from the match results.

Chronograph Station Rules and Policies

44. The Chronograph Station is considered an official stage in the match and subject to all sections of this rulebook.
45. The Chrono Officer is the CRO for the chronograph stage and issues range commands appropriate to the requirements of the Chrono Station.
46. Shooters are prohibited from handling their firearm except as specifically required to do so by the Chrono Officer.
47. Unless otherwise authorized by the Chrono Officer, once the firearm and magazine are surrendered for testing, neither may be removed from the Chrono Station until the testing is complete.

a. Should the primary safety mechanism(s) be found to be non-functional or missing, the Range Master will declare the firearm as unsafe and order that it be withdrawn from the competition until such time the primary safety mechanisms are functional or are replaced with functioning parts or firearm. The competitor will be allowed to leave the Chrono Station with the firearm to effect repairs and return at a later time for inspection.

b. Should the competitor's magazine(s) fail to meet the requirements of the declared division, the competitor under supervision of the Chrono Officer or the Range Master, may disassemble and reassemble the magazine prior to being re- tested. At no time may the competitor exchange magazine components, make modifications other than cleaning and re-assembly, or leave the Chrono Station while the magazines are being tested.

48. The Chrono Officer will inspect the competitor’s firearm and associated equipment and report any failure of the following to the Range Master:

a. Proper function of the firearm’s primary safety mechanism(s) b. Safe condition and operation c. Compliance with the requirements of the declared Division

49. At the command of the Chrono Officer, the competitor may be required to fire up to six rounds into a designated target or spot on the berm/backstop prior to the competitor’s ammunition sample being tested through the chronograph.
50. The Chrono Officer will perform the competitor ammunition testing procedure as specified above and enter the results on a score sheet suitable for such use.
51. Following testing, should the interim chronograph results be close to the minimum applicable Power Factor floor, it is recommended that any remaining rounds of the competitor’s sample ammunition be secured and retained at the Chrono Station for potential later reference or additional testing.
52. A recommended procedure to follow at the chronograph station is to advise the squad/individual competitors via Written Stage Briefing to not to handle the firearm until instructed. The Chronograph CRO should have a station next to him where the competitor, when called, can step up and when instructed to MAKE READY, show a cleared firearm and then place it on the table per the CRO’s instructions. The competitor will also provide an empty magazine and may be asked for the longest magazine used in the match. The competitor will then step back until the chronograph process is completed. The Chronograph CRO, after the ammo has been tested, will make sure the firearm is empty and then place it on the table and call the competitor to UNLOAD AND SHOW CLEAR, followed by IF CLEAR, HAMMER DOWN, HOLSTER. The empty magazine will be returned at this time and the next competitor called to the line.