Precision Sniper Rifle post by Dynamic Research

[ELR researcher]

I finally got around to reading the 9/9/11 post on Dynamic Researches' blog about what they belive is the falacy of assuming the 338 (PSR) requires a 300 grain projectile for ELR performance optimization. I'd appreciate the ballisticians and highly experienced ELR shooter's take on their analysis and "alternative" solution. Their blog post is at http://site.dynamicresearchllc.com/PredatorPerformanceNotes/2011/09/09/precision-sniper-rifle/

Thanks.

 

[Noel Carlson]

Re: Precision Sniper Rifle post by Dynamic Researc

Nonsense.

There is no aerodynamic penalty for mass "that has to go somewhere", unless it goes into extension of the engraving footprint. Some of the solids are the worst offenders here, and multiple engraving-band designs are especially susceptible.

Internal ballistics, and dynamic stability, are the only real considerations to focus upon with an increase of mass/length, assuming structural integrity of the projectile is maintained.

 

[cali_tz]

Re: Precision Sniper Rifle post by Dynamic Researc

I went thru the blog post, but it read like gibberish to me. Maybe there's something in their argument, but it's not presented well. The standard to me in ballistics analysis is Bryan Litz's book where he presents mathematical models in plain english and then his field testing comparing real world results to the model predictions.

 

[greentimber]

Re: Precision Sniper Rifle post by Dynamic Research

"......it’s a 236 grain dose of reality that can repeatedly drill 10” groups at 2200m."

I read the whole thing. While I wish it were "reality" the statement above (among other things) is laughable. The single variable of a 20fps extreme spread in velocity variation (likely wishful thinking for the millions of rounds of mass produced ammo required by PSR) produces a roughly 1.5MOA (approx 40 in) elevation spread at 2200m. That's before we introduce any variables (error) from the rifle or the shooter. "Reality" (and the entire ammunition industry) tells us that we don't currently have the technology to make ammo with velocity variations of zero. I'm not from Missouri, but on this I'd say "Show me." If it works, I'll put it in PSR (which has not been canceled, btw).

https://www.fbo.gov/index?s=opportunity&...3c&_cview=0





Trajectory (Simplified)
Input Data
Ballistic Coefficient: 1.020 G1 Caliber: 0.338 in
Bullet Weight: 236.0 gr
Muzzle Velocity: 2900.0 ft/s
Sight Height: 1.50 in Line Of Sight Angle: 0.0 deg
Cant Angle: 0.0 deg
Wind Speed: 10.0 mph Target Speed: 10.0 mph
Temperature: 59.0 °F Pressure: 29.92 in Hg
Humidity: 0.0 % Altitude: 0.0 ft
Std. Atmosphere at Altitude: No Pressure is Corrected: Yes
Zero at Max. Point Blank Range: No Target Relative Drops: Yes
Column 1 Units: 1.00 mil Column 2 Units: 1.00 MOA
Round Output to Whole Numbers: No
Output Data
Elevation: 3.520 MOA Windage: 0.000 MOA
Atmospheric Density: 0.07647 lb/ft³ Speed of Sound: 1116.4 ft/s
Maximum PBR: 342 m Maximum PBR Zero: 288 m
Range of Maximum Height: 156 m Energy at Maximum PBR: 3431.7 ft•lbs
Sectional Density: 0.295 lb/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(m) (mil) (MOA) (mil) (MOA) (ft/s) (none) (ft•lbs) (s) (mil) (MOA)
100 -0.0 -0.0 0.1 0.3 2797.6 2.506 4100.6 0.115 5.1 17.7
200 -0.5 -1.7 0.2 0.6 2697.5 2.416 3812.5 0.235 5.2 18.0
300 -1.1 -3.9 0.3 1.0 2599.7 2.329 3541.0 0.359 5.3 18.4
400 -1.8 -6.3 0.4 1.3 2504.0 2.243 3285.1 0.487 5.4 18.7
500 -2.6 -9.0 0.5 1.7 2410.4 2.159 3044.0 0.621 5.5 19.1
600 -3.4 -11.8 0.6 2.1 2318.7 2.077 2816.8 0.759 5.7 19.5
700 -4.3 -14.7 0.7 2.5 2229.0 1.996 2603.1 0.904 5.8 19.8
800 -5.2 -17.9 0.8 2.9 2141.2 1.918 2402.1 1.054 5.9 20.2
900 -6.2 -21.2 1.0 3.3 2055.4 1.841 2213.4 1.210 6.0 20.7
1000 -7.2 -24.7 1.1 3.7 1971.7 1.766 2036.8 1.373 6.1 21.1
1100 -8.3 -28.4 1.2 4.2 1890.1 1.693 1871.7 1.543 6.3 21.6
1200 -9.4 -32.4 1.4 4.7 1810.7 1.622 1717.8 1.721 6.4 22.0
1300 -10.6 -36.6 1.5 5.1 1733.7 1.553 1574.9 1.906 6.6 22.5
1400 -11.9 -41.0 1.6 5.7 1659.3 1.486 1442.6 2.099 6.7 23.0
1500 -13.3 -45.8 1.8 6.2 1587.6 1.422 1320.6 2.302 6.9 23.6
1600 -14.8 -50.8 2.0 6.8 1518.8 1.360 1208.6 2.513 7.0 24.1
1700 -16.3 -56.2 2.1 7.3 1453.2 1.302 1106.4 2.734 7.2 24.7
1800 -18.0 -62.0 2.3 7.9 1391.0 1.246 1013.7 2.965 7.4 25.3
1900 -19.8 -68.1 2.5 8.6 1332.5 1.194 930.3 3.207 7.5 25.9
2000 -21.7 -74.6 2.7 9.2 1278.0 1.145 855.8 3.459 7.7 26.6
2100 -23.7 -81.6 2.9 9.8 1227.8 1.100 789.9 3.721 7.9 27.2
2200 -25.9 -89.1 3.1 10.5 1182.2 1.059 732.3 3.994 8.1 27.9



Trajectory (Simplified)
Input Data
Ballistic Coefficient: 1.020 G1 Caliber: 0.338 in
Bullet Weight: 236.0 gr
Muzzle Velocity: 2880.0 ft/s
Sight Height: 1.50 in Line Of Sight Angle: 0.0 deg
Cant Angle: 0.0 deg
Wind Speed: 10.0 mph Target Speed: 10.0 mph
Temperature: 59.0 °F Pressure: 29.92 in Hg
Humidity: 0.0 % Altitude: 0.0 ft
Std. Atmosphere at Altitude: No Pressure is Corrected: Yes
Zero at Max. Point Blank Range: No Target Relative Drops: Yes
Column 1 Units: 1.00 mil Column 2 Units: 1.00 MOA
Round Output to Whole Numbers: No
Output Data
Elevation: 3.551 MOA Windage: 0.000 MOA
Atmospheric Density: 0.07647 lb/ft³ Speed of Sound: 1116.4 ft/s
Maximum PBR: 339 m Maximum PBR Zero: 286 m
Range of Maximum Height: 155 m Energy at Maximum PBR: 3389.9 ft•lbs
Sectional Density: 0.295 lb/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(m) (mil) (MOA) (mil) (MOA) (ft/s) (none) (ft•lbs) (s) (mil) (MOA)
100 -0.0 -0.0 0.1 0.3 2778.1 2.488 4043.5 0.116 5.2 17.8
200 -0.5 -1.7 0.2 0.6 2678.4 2.399 3758.7 0.236 5.3 18.2
300 -1.1 -4.0 0.3 1.0 2581.0 2.312 3490.3 0.361 5.4 18.5
400 -1.9 -6.4 0.4 1.3 2485.7 2.226 3237.3 0.491 5.5 18.8
500 -2.6 -9.1 0.5 1.7 2392.5 2.143 2998.9 0.625 5.6 19.2
600 -3.5 -11.9 0.6 2.1 2301.2 2.061 2774.4 0.765 5.7 19.6
700 -4.3 -14.9 0.7 2.5 2211.8 1.981 2563.2 0.910 5.8 20.0
800 -5.3 -18.1 0.8 2.9 2124.4 1.903 2364.6 1.062 5.9 20.4
900 -6.3 -21.5 1.0 3.3 2039.0 1.826 2178.3 1.219 6.1 20.8
1000 -7.3 -25.1 1.1 3.8 1955.7 1.752 2003.9 1.384 6.2 21.3
1100 -8.4 -28.9 1.2 4.2 1874.5 1.679 1841.1 1.555 6.3 21.7
1200 -9.6 -32.9 1.4 4.7 1795.6 1.608 1689.3 1.734 6.5 22.2
1300 -10.8 -37.1 1.5 5.2 1719.1 1.540 1548.4 1.921 6.6 22.7
1400 -12.1 -41.7 1.7 5.7 1645.2 1.474 1418.1 2.116 6.8 23.2
1500 -13.5 -46.5 1.8 6.3 1574.0 1.410 1298.1 2.320 6.9 23.8
1600 -15.0 -51.6 2.0 6.8 1505.9 1.349 1188.1 2.533 7.1 24.3
1700 -16.6 -57.1 2.2 7.4 1440.9 1.291 1087.8 2.756 7.2 24.9
1800 -18.3 -62.9 2.3 8.0 1379.4 1.235 996.9 2.989 7.4 25.5
1900 -20.1 -69.2 2.5 8.6 1321.6 1.184 915.2 3.233 7.6 26.1
2000 -22.1 -75.8 2.7 9.3 1267.9 1.136 842.3 3.487 7.8 26.8
2100 -24.1 -82.9 2.9 9.9 1218.6 1.092 778.1 3.751 8.0 27.5
2200 -26.3 -90.5 3.1 10.6 1174.0 1.052 722.1 4.026 8.2 28.1

 

[ney1]

Re: Precision Sniper Rifle post by Dynamic Research

PSR called for specific performance numbers at 1500 meters, any bullet that met those numbers would have been considered. 10" groups at 2000 yards, maybe if they are shooting 3 shot groups, tell them to shoot 5 or 10 shot groups. Bolt statements, most likely they couldn't find one of the rifle builders that would use their product in the solicitation. Plus PSR isn't canceled just being rewritten to accommodate more than one services needs.

By the way if any rifles were not able to meet the performance standard it was just as attributed to the necessity of most guns to run shorter barrels to meet the length and weight requirements, fortunately for the SRS it is bullpup.