This may have been discussed here before but could not fine it sooooooo---
How far from the muzzle should one place a chronograph ??
A further question is a what distance from the muzzle does a projectile achieve max velocity? My assumption is that when a round is fired it continues to accelerate for a distance after it leaves the barrel. I would think this is dependent on caliber and bullet ---- but ??
Thanks
G

I have heard anywhere from 5-15 feet and i set mine usually about 10. I say set it far enough that when you accidentally shoot it, the pieces won't hit you in the head.

if you put the chrono screens too close, the muzzle blast can damage the screen shades and the muzzle blast can cause the chrono to give false readings. The gases in the blast move much faster for a short distance than the projectile and can trigger the screens before the projectile gets there.

As far as I know, the bullet starts decelerating as soon as it leave the muzzle. The bullets only source of energy is the pressure in the barrel.

A distance of 10 to 12 feet has always worked well for me.

No, a round IMMEDIATELY begins to lose velocity as soon as it clears the barrel and the pressure of the propelling gasses diffuse laterally. This might actually be an inch or two from the muzzle, but for practical purposes it is at the muzzle and all velocities beyond that, even ten feet away, are reduced by air resistance.

I normally place my chronograph screens approximately ten feet from the muzzle. This is far enough that the "start" screen is neither damaged nor "fooled" by the muzzle blast, and close enough to keep the shooting lane reasonably wide. Most high velocity centerfires will loose about 8-10 fps in the first ten feet, but this depends on the B.C. of the particular bullet.

I normally do 12 for rifle,10 for handgun. The reason is twofold. Some heavy recoiling rifles and pistols will cause errors from concussion of blast and in handguns unburnt powder will also cause errors.
Also almost all ballistic programs give an option of 10 or 12 ft so for those to work the chrony must be at those.

quote:

Originally posted by icemanls2:
I have heard anywhere from 5-15 feet and i set mine usually about 10. I say set it far enough that when you accidentally shoot it, the pieces won't hit you in the head.

There are too types of people who own chronographs those who have shot them and those who well shoot them

I set mine at about 10 feet

quote:

A distance of 10 to 12 feet has always worked well for me.

X2

quote:

Originally posted by Woodmnctry:
This may have been discussed here before but could not fine it sooooooo---
How far from the muzzle should one place a chronograph ??
A further question is a what distance from the muzzle does a projectile achieve max velocity? My assumption is that when a round is fired it continues to accelerate for a distance after it leaves the barrel. I would think this is dependent on caliber and bullet ---- but ??
Thanks
G

I put my chrono 5 yds. in front of the muzzle and have never had a problem.
No! No! No! A bullet's max. velocity is at the muzzle AND, FYI, it immediately begins dropping due to the pull of gravity as well. That's another purpose of sights.
BTW, when I want to correct my velocities from the chrono back to the muzzle, I've found that I lose approx. 10 fps in velocity for a distance of 5 yds. To do this, I use a ballistics program for the correction factor.
Bear in Fairbanks

quote:

There are two types of people who own chronographs those; who have shot them and those who well shoot them

It's just matter of time .....

I've marked the electrical cord from the unit to the display on my Chrony with tape, in 1 foot increments from 10' forwards - that way I know exactly EVERY time how far the unit is away from my muzzle. No fuss, no muss.

I use 12' as my standard; who cares as long as it's >10' and the same every time - for you.

As Stoney says; the muzzle blast any closer may play havoc w/the readings.

It also helps to replace the metal rods for the sunscreens with wooden dowels - they tend to part ways w/less explosive results than the metal rods.

Also mark the dowels with red electrical tape/magic marker @3" above the unit. That way you easily determine thru the scope/sights from +/- 12' if your line of sight is above the markers.

I also attach a @10lb. sandbag to the tripod (most have a hook between the legs) that really helps hold it steady in a breeeze.

The taped dowels are really helpful in avoiding smacking a Chrony in the Kisser; and believe you me when you do the deed with a 9,3x74R it sends the remainder(s) of the unit about 25 yards downrange. DRT!

Seems that all the pertinent info has come out. I'm about 15 feet, my club has covered firing points and i have to get the chronograph out to the sun.

Thanks -- that is what I was looking for -- I may have been setting a bit too close as the screens blew off --- like the idea of marking the cord
G

A couple other tips..

DON'T try to chronograph shotgun loads without a piece of half or three quarter plywood in front of your instrument to catch the wad. You cut a small window for the shot to pass through. The wad will wipe out a chronograph!

Move your chronograph back some if you shoot black powder. You don't want black powder fouling to get a chance to settle in your electronics or sky screens. You can tell how far by watching the smoke when someone else shoots your gun for you.

quote:

Originally posted by tiggertate:
A couple other tips..

DON'T try to chronograph shotgun loads without a piece of half or three quarter plywood in front of your instrument to catch the wad. You cut a small window for the shot to pass through. The wad will wipe out a chronograph!

Same for gas checks and sabots.

I have blown the screens off my chrony while shooting my Wby. Scared the crap out of me, as I was SURE I'd hit it.

Nope, just the muzzle blast blew the screen off. I set it back a little further, 12 ft, and no further problems.

quote:

I put my chrono 5 yds. in front of the muzzle and have never had a problem.
BTW, when I want to correct my velocities from the chrono back to the muzzle,
I've found that I lose approx. 10 fps in velocity for a distance of 5 yds.
To do this, I use a ballistics program for the correction factor.
Bear in Fairbanks

The rule of thumb.
5 paces out that is what I do as well as Magnums generally have more muzzle blast.
I do not work the velocity back, it is inconsequential.
10 fps over practical hunting distances is neither here nor there.

Warrior

Even at 15 feet my screens whip around with a .308 Winchester.

What is most importaint is that you put your's at the same distance each time.

Organizations that expect certain velocity ranges for competition usually call for 15 feet to the center of the sensor bar.

If you are concerned with muzzle blast changing
the reading (and you should be) back away another 10 feet and see if there is a larger than normal change. Slower powder seems to
need a longer distance.
good luck!

Most balistic programs give you the ability to adjust you cromo speed to muzzle speed by giving it the distance to cromo.

I do all my testing at 10 feet. I use a Millennium CED and have had no issues with muzzle blast complications. The screens are very generous, unlike my Oehler Model 12, and I have no problems avoiding injury to the equipment.

When I work up loads I am shooting 100 yard groups ans the screens are big enough to allow shooting at up to 15 separate 8 1/2X11 targets.

Greg

This is a question for Hot Core.

Hey HC!!!!!

How far do you put your Chrono from your muzzle?????

quote:

Originally posted by p dog shooter:
There are too types of people who own chronographs those who have shot them and those who well shoot them

I set mine at about 10 feet

there's 3 types.. those two, and lairs about condition 1..

12-14 feet

quote:

Originally posted by rcamuglia:
Hey HC!!!!! How far do you put your Chrono from your muzzle?????

The last Chronograph I used is about 12-hours away, by Interstate. Thats the Perfect distance away from the muzzle.

The instructions on my Chrony Gamma Master says 15 ft for Centerfire rifles, and that has worked for me

quote:

Originally posted by p dog shooter:
There are too types of people who own chronographs those who have shot them and those who well shoot them

Long answer:

Yep! And just what do you mean by term "sky screens?" I don't even set those up anymore!

Shooting bore guns, whether with BP or smokeless, the dilema is to be far enough away that the muzzle blast/unburnt powder doesn't screw things up, but close enough that the cone of wads doesn't obilterate the chrono. Smokeless has less blast but more wads, so no real gain. I've killed two chronos and innumerable sets of screens, to the point that I cleaned off a set most every shot despite trying various types of shields.

I'm a bit gunshy these days and have fired a Greener harpoon gun copy over a chrono many, many times now, but never close enough for a valid reading. I'm always afraid of getting TOO close given the erratic way they fly and killing yet another.

Short answer:

15 feet, and have a plan B for when you kill it.

Bob

I have used several diff brands, currently an Oehler. I get best results w/ handgun @ 15ft & rifles @ 20ft. A magnum round can cause too much of a shockwave & messs w/ the screen readings & the Oehler has very good screens. Any variation from actual muzzle vel is meaningless.