Chronograph distance from muzzle?

K

kdvarmint

Guest
Does it make a difference if the chronograph is 10' or 15' from the muzzle?
 
Depends what you're expecting from a chronograph.

If you're like me & using one initially to identify correlations between velocity characteristics & accuracy, then it is inconsequential, other than it's easier to shoot above the sensors the closer the screens are to you if you're using a number of aiming marks horizontally across a target sheet. However, if (when) you plan to feed those figures into suitable ballistic tables to determine come ups (I shoot 300-1200 yards), then it might be worthwhile using exactly the distance recommended by the manufacturer.

John

PS: For the benefit of trolls, yes, I did recognise the forum in which this is posted.
 
the distance is not the big deal.
consistancy is....
too close and muzzle blast can be an issue.
i marked the cords on mine at 10 and 12 feet...
i use 10 feet for most, but the 300 win mag likes 12...
just note it in your results..be consistant so you can talk apples and apples, not apple and oranges...


mike in co
 
Two reasons I ask. One, my speeds are never quite what others advertise with similar loads and conditions. I know, every gun is different, every scenario is different in some way, but I'm consistently slower....Two, when I make drop charts,"click charts"(Sierra 16), they are usually off at longer distances. I know, conditions change every day. Just wondering if there is a "standard" distance that is used for these things that could be throwing me off.
 
almost every manual is done with test bbls and recievers..not rifles...
expect your milage to be less.
they have better instrumentation than you do....do not expect to match them...
load for YOUR gun not thier advertised numbers..
some times i beat them sometimes i don't, but i am looking for accuracy..not just velocity.

just to confusue you more the military rifle data is chrono'd at 78'


mike in co

kdvarmint said:
Two reasons I ask. One, my speeds are never quite what others advertise with similar loads and conditions. I know, every gun is different, every scenario is different in some way, but I'm consistently slower....Two, when I make drop charts,"click charts"(Sierra 16), they are usually off at longer distances. I know, conditions change every day. Just wondering if there is a "standard" distance that is used for these things that could be throwing me off.
Click to expand...
 
The drop charts are the bigger issue. The rest is giving me what I need. Guess I'll just have to play with different distances.
 
Screen separation distance is important. The greater the separation the better the un

Resolution
 
I would also check and make sure that the distance between the start and stop screens is exactly as per the manual. Small errors here make bigger ones on the chronograph.

Bob
 
I suggest you listen to Lou.

I use 10ft distance and have had no trouble getting on paper at 1000yds

al
 
That is my plan. Thank's for the advise. I have little experience with them, but I was thinking that it must make a difference. As with everything in this game!
 
If I remember correctly, you add 1 foot per foot of distance. Example if your screens are 12 ft from muzzle add 12 ft to your results. Result 3200 fps reading, your muzzle velocity would be 3212 fps. Maybe that would explained the difference in what you read and in actual fact.
 
You can get an accurate answer by running your Sierra program with small increments of distance – like one yard – with the target distance not so far out … like 25 yards. Then, change the “muzzle velocity” you input until the velocity at the distance at which you set your screens matches what you measure. Then you know the velocity drop between muzzle and the screens. And the corresponding muzzle velocity. You can then make your drop charts up with the “true” muzzle velocity.

Harold
 
Harold M said:
You can get an accurate answer by running your Sierra program with small increments of distance – like one yard – with the target distance not so far out … like 25 yards. Then, change the “muzzle velocity” you input until the velocity at the distance at which you set your screens matches what you measure. Then you know the velocity drop between muzzle and the screens. And the corresponding muzzle velocity. You can then make your drop charts up with the “true” muzzle velocity.

Harold
Click to expand...

Good thinkin. I will try that.
 
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