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Picture of Opus Dei
posted
I've got $150 to work with and would prefer metal to plastic. Short of a sale, that pretty much rules out the more-respected names. So I'm looking for recommendations.

The other question is regarding sighting-in. My upper is 10.5" 5.56 and I would like to know what y'all use for distance. I would likely not use this over 100 yards, as I have rifles. Does anybody have data on (say) a 50-yard zero and the impact difference at 25 and 100 yards?

Thanks in advance for any advice.
 
Posts: 5188 | Location: Fort Heathen, Texas | Registered: February 25, 2008Reply With QuoteReport This Post
CAPT Obvious
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Posts: 2852 | Location: SE Michigan | Registered: February 25, 2007Reply With QuoteReport This Post
Freethinker
Picture of sigfreund
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For ballistics I recommend the JBM site.

The critical question is what load you will be using, and especially the bullet velocity for 10.5 inches. Shortening the barrel in such lengths reduces velocity significantly. For example, the velocities I measured with Lake City M193 (55 grain FMJ) were:
16" - 3039 fps
11.5" - 2752 fps
7.5" - 2234 fps

You may be able to find data for 10.5" with an Internet search, and then it’s necessary to know the weight and ballistic coefficient of your bullet.




“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 37161 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
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Picture of Opus Dei
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quote:
Originally posted by sigfreund:
For ballistics I recommend the JBM site.

The critical question is what load you will be using, and especially the bullet velocity for 10.5 inches. Shortening the barrel in such lengths reduces velocity significantly. For example, the velocities I measured with Lake City M193 (55 grain FMJ) were:
16" - 3039 fps
11.5" - 2752 fps
7.5" - 2234 fps

You may be able to find data for 10.5" with an Internet search, and then it’s necessary to know the weight and ballistic coefficient of your bullet.
Thanks, Sigfreund. The barrel is 1:7, so I got some M855, as selection here isn't plentiful. Pretty much all the searching I did brought links to "11.5" versus 10.5". I'll do some more looking and go to JBM.
 
Posts: 5188 | Location: Fort Heathen, Texas | Registered: February 25, 2008Reply With QuoteReport This Post
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Picture of Opus Dei
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quote:
Originally posted by Spiff_P239:
https://www.amazon.com/Magpul-...MAG276/dp/B00CLGLRD0

Here ya go. MBUS Pro for $154.
Nice..I didn't even know Magpul had metal sights. Found lots of stuff for more costly brands like Troy or pot metal Nc Star stuff.
 
Posts: 5188 | Location: Fort Heathen, Texas | Registered: February 25, 2008Reply With QuoteReport This Post
Freethinker
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Based on one source, it seems that M855 will run about 2600 fps or a bit more from a 10.5 inch barrel.

Standard atmospheric conditions and the data for the M855 bullet:
Velocity: 2600 fps
Weight: 62 grains
Ballistic Coefficient, G7: 0154
Height of sight over bore: 2.5 inches (estimated)

With a 50 yard zero this is the trajectory per JBM:

25 yards: - 1.1 inch (below line of sight)
50 yd: 0
75 yd: + 0.7 inch (above line of sight)
100 yd: + 1.1 inch
125 yd: + 1.0 inch
150 yd: + 0.5 inch
175 yd: - 0.5 inch (below line of sight)
200 yd: - 1.9 inch




“Most men … can seldom accept the simplest and most obvious truth if it … would oblige them to admit the falsity of conclusions … which they have woven, thread by thread, into the fabrics of their lives.”
— Leo Tolstoy
 
Posts: 37161 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
Member
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I like the MBUS Pros and have them on two guns.

There will be some vets day sales coming.
 
Posts: 2015 | Location: Iowa | Registered: February 24, 2011Reply With QuoteReport This Post
Bolt Thrower
Picture of Voshterkoff
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Primary Arms has the metal magpul sights for 152.
 
Posts: 7732 | Location: Woodinville, WA | Registered: March 30, 2004Reply With QuoteReport This Post
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