VELOCITY at Muzzle / at 10 Feet? - The HuntingPA.com Outdoor Community
 
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post #1 of 9 (permalink) Old 08-15-2016, 06:32 AM Thread Starter
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VELOCITY at Muzzle / at 10 Feet?

Exterior Ballistic Tables give you muzzle velocity,but your chronograph says set up 10 feet from muzzle.
So how much velocity do you lose in that 10 feet [3 yards]?
What i am wondering is to get to the velocity you want you will have to load a little bit hotter and go by your chronograph?

WILLY P
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post #2 of 9 (permalink) Old 08-15-2016, 11:59 AM
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Re: VELOCITY at Muzzle / at 10 Feet?

You can buy a chronograph that will read muzzle velocity.To answer your question you need to know velocity,bullet weight and coefficient.In my 204 Ruger it is about 7.23 FPS.Nothing worth noting actually.The tables mostly use a 24" barrel that raises velocity over most production rifles.My 22-250 with a 26" barrel clocks about 200 FPS higher than the tables.In use speed is not as important as consistency and accuracy.Consistency and accuracy can be gained with a chronograph.Do you need one?Nope but it is kind of cool knowing what the actual speed is.If you want do try and duplicate a load with another powder.

Bob Seger,till it shines.
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post #3 of 9 (permalink) Old 08-15-2016, 01:39 PM
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Re: VELOCITY at Muzzle / at 10 Feet?

If you get to close the muzzle, gas being pushed out ahead of the bullet may cause too many errors and false readings... As far as actual fps, it would be so small it wouldn't be worth even mentioning, your standard deviation would likely be more.. The new magneto speeds bar attach right to the muzzle, I would guess they figured out how to deal with blast, gas, etc, I use the old fashion chrony and I just set it out in front 10-15 feet and it works fine there, any closer and error seems to come up half the time.
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post #4 of 9 (permalink) Old 08-15-2016, 02:03 PM
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Re: VELOCITY at Muzzle / at 10 Feet?

The difference in actual velocity at the crown of the muzzle and instrumental velocity at 10 (or 20-25 feet) is not significant enough to make a difference in what 99.9% of guys are doing with those numbers.

I get my instrumental velocities on a couple of my rifles at 25 feet because muzzle wash has, a few times, rolled the chrono.......tripod and all.....right over any closer. I'm afraid closer would damage the chrono.

I have, many times, taken those 25 foot numbers, plugged them into a ballistics program, adjusted my scope accordingly and taken my next shot at a 300 yard target and been within 1/2 to 1 inch of the predicted P.O.I.

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post #5 of 9 (permalink) Old 08-15-2016, 02:06 PM
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Re: VELOCITY at Muzzle / at 10 Feet?

Agreed...the difference is beyond negligible to the VAST majority of those using a Chrony.

Another really important use of a chrony is to check pressure of your loads. Yes, you can "read tea leaves" by looking at primers and such, but the true measure is speed. There is no black magic, and no free lunch. If speed is running where it would equal high pressure, you have high pressure. There's no way around it.

I would very much enjoy one of the new LabRadar chrony's, but I can't justify the cost at this point.

I've heard good reports on the Magneto Speed, I just worry about it affecting groups, since it would in theory affect barrel harmonics. I tend to chrony as much as I can, even when developing loads, for the reasons above. Pressure can be identified through speed. Every time.
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post #6 of 9 (permalink) Old 08-15-2016, 02:33 PM
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Re: VELOCITY at Muzzle / at 10 Feet?

The first time I tried my chronograph, I had it too close to the muzzle. The blast blew the chronograph off the bench and shattered the screen.
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post #7 of 9 (permalink) Old 08-15-2016, 02:34 PM
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Re: VELOCITY at Muzzle / at 10 Feet?

The first time I tried my chronograph, I had it too close to the muzzle. The blast blew the chronograph off the bench and shattered the screen.
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post #8 of 9 (permalink) Old 08-15-2016, 06:54 PM
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Re: VELOCITY at Muzzle / at 10 Feet?

LabRadar chrony,I would love to have one.At $560 the wife might speak up.

Bob Seger,till it shines.
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post #9 of 9 (permalink) Old 08-15-2016, 07:01 PM
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Re: VELOCITY at Muzzle / at 10 Feet?

Quote:
Originally Posted by Hiamovi
LabRadar chrony,I would love to have one.At $560 the wife might speak up.
Hence my hesitation as well.....

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