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Widder, SASS #59054

Reloaders: something to think about.....

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If you reload and particularly, if you chronograph your reloads, you need to consider this information:

 

When you set your Chronograph 10' from your muzzle,  and then cypher your velocity averages,  your

muzzle energy AIN'T really 'muzzle energy'.    Its 10' from muzzle energy.

 

When somebody sets up their Chronograph about 10'

from their muzzle and then uses those velocities to tell you how much 'muzzle energy' is generated,

The energy generated would actually be ..... "Energy 10' from the muzzle".

 

I've been guilty of this in the past, but I must admit I get annoyed when some of our 'Pros' try to

impress us with great muzzle energy stats when in effect, the bullet velocities used to establish

the muzzle energy was taken 10' (and sometimes further) from the muzzle.

 

I wonder if ALPO ever thought of this?

 

..........Widder

 

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I think 10’ is the gun writing industry’s standard for muzzle energy measurements. But apparently, in long range shooting, where your chronograph is set up makes a difference.

 

https://www.appliedballisticsllc.com/Articles/ABDOC121_VelocityDecay.pdf

 

Here is an article about a more scientific way of setting chronographs.

 

http://www.exteriorballistics.com/ebexplained/5th/2311.cfm

 

If you notice in the article above they talk about a blast shield for the chronograph at the muzzle end. I think this statement explains why gun writers and others use 10’ as a distance. They don’t want to damage their chronographs.

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Also-Make sure you have fresh or fully charged batteries in place for each session.

I set my screens 10-12' from the end of my bench.

OLG

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I'm not so sure it really matters.  In time, distance, speed, energy stuff, 10' isn't much of a distance.  Nano seconds and science sort of stuff.  I'm more concerned whether or not the target goes "Klang."  Or if the animal I shoot, drops.  How quickly the projectile goes through the critter, or how much energy the projectile imparts to the target is kinda moot.  The only folks really interested in energy, and time of flight and stuff are most usually way good sniper types whom are shooting at mile or more.

 

I don't own a Chrono.  Never have.  Actually don't need one.  I can't think as fast as a projectile travels the six or seven yards to the targets.  So long as the projectile travels from the gun to target .... I'm good.

 

Most of the Four Going has nothing to do with the OP.  Thus, should you choose to completely ignore it, feel free.  I won't be at all insulted.  Cantine Flas.

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Are you saying that it is an inaccurate measure as the muzzle energy is actually less at the true muzzle? 

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I apparently set my chrono too close for my 45-70's sake. On the tenth shot it blew the face plate off and reset the chrono. No damage, but what a PIA to get the plastic face back in! I have now made a plexi shield for the chrono.

:o:ph34r:

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It's too early in the morning, raining, and no shoot for me today so not in good mood. But if I figure it out right at 800 fps it takes .0125 of a second to travel 10 feet or something like that. Somewhere around Matt Blacks speed which is the speed of light, I think.

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Ran some numbers through my ballistics software and

 

.38 Special 158 gr LRN looses about 0.7 fps for every yard travelled for the first 20 yards.

 

.45 Colt 250 gr LRN looses about 0.85 fps for every yard travelled for the first 20 yards.

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Posted (edited)

Anyone testing under SAMMI rules converts the energy and velocity back to the muzzle , Or states otherwise and gives the distance used .....

SAMMI testing also requires the use of SAMMI  Minium spec. barrels,,, Minium Spec. Chambers,,, ETC,,,,,, this is a very precise set of rules ...

And this causes testing to be an expensive process ... I figure each barrel costs about $800 dollars by the time it's chambered and fitted to my firing Fixture and ready to go ....

This does not begin to cover the equipment costs to actually Do the Testing....

 

Jabez Cowboy  

Edited by Jabez Cowboy,SASS # 50129

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pickin' nits?:ph34r:

 

I would think that there is a device that could cipher the actual muzzle energy at the muzzle taking bullet weight, velocity (and, maybe, other stuff), but then I could not afford it. 

 

It scrambles my brain to realize that "they" can compute the BC of a bullet at any and all points of its flight path. 

When I started shooting in IPSC, we had to show we were loaded hot enough by shooting a steel plate hanging from a steel rod. We had to move the plate back enough to quality. Could be another way to figger muzzle energy. 

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