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Posted: 11/1/2001 2:30:25 PM EDT
Any sources of info?
Link Posted: 11/1/2001 6:27:41 PM EDT
Kevin - did you input the muzzle velocity, and if so, where did you get it?
Link Posted: 11/1/2001 7:20:29 PM EDT
FROM A POST on ar15.com back in July of 2000

TOM.32
Member posted 07-22-2000 20:10
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I finally took the time to chrono different barrels for each length that I have and some different ammo just to see what the results would be. No real surprises.
Chronograph,
Oehler Model 35 w/ 3 screens
distance 10'
10 shots each barrel with each make of ammo

85 degrees
40% humidity (approx.)
1290' above msl

Barrels,
20" Colt 1/7 Govt.
16" Colt 1/9 lightweight
14.5" Colt 1/7 M4
11.5" Colt 1/7 commando
10.25" Colt 1/9 lightweight (16" cut down)

Lake City M193 1997
20" - 3255 fps
16" - 3145 fps
14.5" - 3075 fps
11.5" - 2884 fps
10.25 - 2767 fps

Q3131A 1999 Lot PF20
20" - 3152 fps
16" - 3051 fps
14.5" - 2951 fps
11.5" - 2732 fps
10.25" - 2605 fps

IMI M193
20" - 3131 fps
16" - 3032 fps
14.5" - 2917 fps
11.5" - 2726 fps
10.25" - 2598 fps

Rem UMC
20" - 3122 fps
16" - 3001 fps
14.5" - 2878 fps
11.5" - 2705 fps
10.25" - 2499 fps

No misfires, ftf's, chambering, or extraction/ejection problems.

Individual results may vary. I have done a few barrels at other times when it was colder (55 degrees and 70 degrees) and the Lake City was closer to the others in velocity. It seems like I read somewhere that the powder used is more temperature sensitive? I thought about doing some Lake City M855 but didn't think I would have time. Might try that next time.

Link Posted: 11/1/2001 9:09:17 PM EDT

Rng. // Vel. // Energy // Traj.
000 // 3202 // 1252 // -1.50
100 // 2911 // 1035 // 0.00
200 // 2635 // 848 // -1.57
300 // 2376 // 690 // -8.64
400 // 2136 // 557 // -21.72
500 // 1913 // 447 // -42.05


Kevin and others - herein lies my problem:

I am zeroed at 25meters. I keep the rear on "4" which is dead on at 50 yrds. Using this I am having to aim about 6" low at 100 (at the waist to hit the center of the chest)and more like 2ft low at 200 (like the knee to hit the center of the chest).

I can not zero at 100 (as I would like to) b/c my Ashley front sight will not turn down any lower (that is correct? right - if I am zeroed at 25m the front would have to come down to be able to zero at 100?)

The santose method is a maybe but that is another series of questions.

Why does the above chart not jive with the way that I have to aim?
Link Posted: 11/2/2001 6:00:29 AM EDT
[Last Edit: 11/2/2001 7:16:30 AM EDT by Kevin]
Link Posted: 11/2/2001 6:57:43 AM EDT
55FMJ 0.250 ballistic coefficient
Muzzle velocity = 3000 fps from 16" barrel
Sight line above bore line = 2.5"

Try this link:

www.norma.cc/htm_files/javapagee.htm
Link Posted: 11/2/2001 1:02:22 PM EDT
Great sight!!

Can you explain Sight line above bore line and how it is calculated?
Link Posted: 11/2/2001 1:05:50 PM EDT
Ahh.... I love google


Sightline - distance from the center of the bore to the center of the scope, usually about 1.5 inches, or for open sights this is the distance from the center of the bore to the top of the front sight blade
Link Posted: 11/2/2001 1:06:54 PM EDT
So, it is obvious for my needs I want to zero at 50yrds.
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