Introduction
M193 should give you around 3200-3250 fps from the muzzle of a 20" weapon and around 3150 from a 16" weapon.
M855 should give you around 3050-3100 from a 20" weapon and around 2950-3000 from a 16" weapon.
Here's some Q3131A (M193) ballistic data, of course your mileage may vary:
Altitude 1480 feet 70 degrees 50% humidity. 55gr FMJBT Average cD over velocities: .267
Range |
Velocity |
Energy |
Momentum |
Drop |
Bullet Path |
Time of Flight |
(Yards) |
(Ft/Sec) |
(Ft/Lbs) |
(Lb-Sec) |
(inches) |
(inches) |
(Seconds) |
0 |
3250.0 |
1289.70 |
0.79 |
0 |
-1.50 |
0.000000 |
25 |
3161.2 |
1220.20 |
0.77 |
-0.1 |
-0.79 |
0.023399 |
50 |
3074.2 |
1154.00 |
0.75 |
-0.43 |
-0.29 |
0.047458 |
75 |
2988.9 |
1090.80 |
0.73 |
-0.98 |
-0.02 |
0.072201 |
100 |
2905.4 |
1030.70 |
0.71 |
-1.77 |
0.00 |
0.097652 |
125 |
2823.4 |
973.30 |
0.69 |
-2.83 |
-0.23 |
0.123839 |
150 |
2742.9 |
918.70 |
0.67 |
-4.15 |
-0.74 |
0.150790 |
175 |
2663.9 |
866.50 |
0.65 |
-5.76 |
-1.54 |
0.178536 |
200 |
2586.3 |
816.80 |
0.63 |
-7.68 |
-2.64 |
0.207109 |
225 |
2510.1 |
769.30 |
0.61 |
-9.93 |
-4.06 |
0.236545 |
250 |
2435.0 |
724.00 |
0.59 |
-12.52 |
-5.83 |
0.266882 |
275 |
2361.3 |
680.80 |
0.58 |
-15.47 |
-7.97 |
0.298160 |
300 |
2288.8 |
639.70 |
0.56 |
-18.82 |
-10.50 |
0.330422 |
325 |
2217.6 |
600.50 |
0.54 |
-22.58 |
-13.44 |
0.363712 |
350 |
2147.5 |
563.10 |
0.52 |
-26.78 |
-16.82 |
0.398081 |
375 |
2078.8 |
527.60 |
0.51 |
-31.45 |
-20.68 |
0.433578 |
400 |
2011.3 |
494.00 |
0.49 |
-36.63 |
-25.03 |
0.470258 |
425 |
1945.2 |
462.00 |
0.48 |
-42.34 |
-29.93 |
0.508177 |
450 |
1880.4 |
431.70 |
0.46 |
-48.63 |
-35.40 |
0.547394 |
475 |
1817.0 |
403.10 |
0.44 |
-55.53 |
-41.48 |
0.587972 |
500 |
1755.1 |
376.10 |
0.43 |
-63.09 |
-48.22 |
0.629972 |
And for a 16" barrel:
Range |
Velocity |
Energy |
Momentum |
Drop |
Bullet Path |
Time of Flight |
(Yards) |
(Ft/Sec) |
(Ft/Lbs) |
(LB-Sec) |
(inches) |
(inches) |
(Seconds) |
0 |
3100.0 |
1173.4 |
0.76 |
0.00 |
-1.50 |
0.00000 |
25 |
3014.2 |
1109.4 |
0.74 |
-0.12 |
-0.75 |
0.02454 |
50 |
2930.2 |
1048.4 |
0.72 |
-0.47 |
-0.24 |
0.04977 |
75 |
2847.7 |
990.2 |
0.70 |
-1.08 |
0.01 |
0.07574 |
100 |
2766.8 |
934.7 |
0.68 |
-1.95 |
0.00 |
0.10246 |
125 |
2687.4 |
881.8 |
0.66 |
-3.11 |
-0.30 |
0.12996 |
150 |
2609.4 |
831.4 |
0.64 |
-4.57 |
-0.89 |
0.15828 |
175 |
2532.7 |
783.3 |
0.62 |
-6.35 |
-1.81 |
0.18746 |
200 |
2457.3 |
737.3 |
0.60 |
-8.47 |
-3.06 |
0.21752 |
225 |
2383.2 |
693.5 |
0.58 |
-10.94 |
-4.68 |
0.24851 |
250 |
2310.3 |
651.8 |
0.56 |
-13.80 |
-6.67 |
0.28048 |
275 |
2238.7 |
612.0 |
0.55 |
-17.07 |
-9.08 |
0.31345 |
300 |
2168.3 |
574.1 |
0.53 |
-20.77 |
-11.91 |
0.34749 |
325 |
2099.2 |
538.1 |
0.51 |
-24.93 |
-15.21 |
0.38265 |
350 |
2031.3 |
503.8 |
0.50 |
-29.58 |
-19.00 |
0.41897 |
375 |
1964.8 |
471.4 |
0.48 |
-34.77 |
-23.32 |
0.45651 |
400 |
1899.6 |
440.6 |
0.46 |
-40.51 |
-28.20 |
0.49533 |
425 |
1835.8 |
411.5 |
0.45 |
-46.86 |
-33.69 |
0.53550 |
450 |
1773.5 |
384.0 |
0.43 |
-53.85 |
-39.82 |
0.57707 |
475 |
1712.7 |
358.2 |
0.42 |
-61.53 |
-46.63 |
0.62010 |
500 |
1653.6 |
333.9 |
0.40 |
-69.95 |
-54.19 |
0.66467 |
Buyer Beware:
Velocities are measured from many different "standard" distances. "Muzzle velocities" are almost never actual velocities at the muzzle, but rather velocities at 10, 15 or even 78 feet. Often this can lead to confusion and to the frequent accusation that commercial ammunition's velocity claims on the box are overstated.
It's also always a good idea to look at the conditions any velocity test was performed under. A 30 degree F difference in temperature can result in a 50fps difference at 100 meters. 1000 feet of elevation can result in 30-40fps of velocity difference.