When shooting though a chronograph does the gun effect the variance in the fps or is it all the load. Also does the shooter effect the fps?
Does the gun effect the fps
- Thread starter jaym_100
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Re: Does the gun effect the fps
Gun, ammo, shooter, they all effect it. A lot of people get hung up on chrono results but I wouldn't fret about it.
Gun, ammo, shooter, they all effect it. A lot of people get hung up on chrono results but I wouldn't fret about it.
Re: Does the gun effect the fps
Basically I can only echo the statements others have made above. To some extent, EVERYTHING effects the numbers on a chronograph. Barrel temperature, to a lesser degree fouling in the barrel, (ie shots 1 to 10 versus shots 150 to 160 without cleaning the barrel) weather, sandbags or rest and if they hold solid or if they let the rifle slide. The shooter CAN effect the reading from shot to shot if he tends to "bear hug" the rifle and then either lets one slip or fires one "free recoil".
The whole point of using a repeatable chronograph of good quality is to get good, usable, repeatable data. Just another reason I keep volumes of field notes on each rifle and ammo combination.
I hope you find the answers your looking for. I hope I didn't confuse the situation for you.
Good luck.
Basically I can only echo the statements others have made above. To some extent, EVERYTHING effects the numbers on a chronograph. Barrel temperature, to a lesser degree fouling in the barrel, (ie shots 1 to 10 versus shots 150 to 160 without cleaning the barrel) weather, sandbags or rest and if they hold solid or if they let the rifle slide. The shooter CAN effect the reading from shot to shot if he tends to "bear hug" the rifle and then either lets one slip or fires one "free recoil".
The whole point of using a repeatable chronograph of good quality is to get good, usable, repeatable data. Just another reason I keep volumes of field notes on each rifle and ammo combination.
I hope you find the answers your looking for. I hope I didn't confuse the situation for you.
Good luck.
Re: Does the gun effect the fps
I believe I have the answer but I meant using the same gun with the same ammo could the person shooting change the FPS but doing something different each time.
I believe I have the answer but I meant using the same gun with the same ammo could the person shooting change the FPS but doing something different each time.
Re: Does the gun effect the fps
+1 for all of the previous posts, as well as from day to day. The chronograph must be set up exactly the same distance from the muzzle each session to have any continuity of results.
For this and all the other reasons, most shooting publications and manuals use an averaqe of multiple groups or shots to come up with a velocity for a given load. (Average of 5, 5 shot groups - for example)
Paul
+1 for all of the previous posts, as well as from day to day. The chronograph must be set up exactly the same distance from the muzzle each session to have any continuity of results.
For this and all the other reasons, most shooting publications and manuals use an averaqe of multiple groups or shots to come up with a velocity for a given load. (Average of 5, 5 shot groups - for example)
Paul
Re: Does the gun effect the fps
Look more to neck tension and case capacities for SD variances from shot to
shot. Not much you as the shooter can do to change bullet speeds. That said
from set up to set up you could show differences. Not being square through the
traps, and as said muzzle distance. And chronos do throw erroneous readings at
times.
Look more to neck tension and case capacities for SD variances from shot to
shot. Not much you as the shooter can do to change bullet speeds. That said
from set up to set up you could show differences. Not being square through the
traps, and as said muzzle distance. And chronos do throw erroneous readings at
times.
Re: Does the gun effect the fps
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigwheeler</div><div class="ubbcode-body"> Not much you as the shooter can do to change bullet speeds. </div></div>
When my 300WM was an 8 lb. hunting rifle, setting my shoulder vs. *almost* free recoil would give significant variances in velocity. Now that it weighs 13 lbs. and wears a very effective muzzle brake, the shooter is taken out of the equation for the most part.
John
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigwheeler</div><div class="ubbcode-body"> Not much you as the shooter can do to change bullet speeds. </div></div>
When my 300WM was an 8 lb. hunting rifle, setting my shoulder vs. *almost* free recoil would give significant variances in velocity. Now that it weighs 13 lbs. and wears a very effective muzzle brake, the shooter is taken out of the equation for the most part.
John
Re: Does the gun effect the fps
Chrony setup, as in distance from the muzzle and I believe even the height at which you shoot thru the sensors will effect the readings you get.
I also believe weather conditions have an effect but i have no evidence to back me up.
I only say this as I have had my chrony give me bogus readings on different days with the same load.
Chrony setup, as in distance from the muzzle and I believe even the height at which you shoot thru the sensors will effect the readings you get.
I also believe weather conditions have an effect but i have no evidence to back me up.
I only say this as I have had my chrony give me bogus readings on different days with the same load.
Re: Does the gun effect the fps
Short answer, yes.
If I read the question right, you're talking about effects during a single testing session.
As such, the barrel temperature and fouling state will bear on individual velocities.
Generally, for me, they tend to speed up when going from cold/clean to warm/fouled.
Greg
Short answer, yes.
If I read the question right, you're talking about effects during a single testing session.
As such, the barrel temperature and fouling state will bear on individual velocities.
Generally, for me, they tend to speed up when going from cold/clean to warm/fouled.
Greg
Re: Does the gun effect the fps
How far do you usually set up the chrono from end of the rifle. The only gun I shot through it until recently had a muzzle break. My 5r muzzle blast messes with it and it won't read if it is very close. Close meaning withing 3 feet.
How far do you usually set up the chrono from end of the rifle. The only gun I shot through it until recently had a muzzle break. My 5r muzzle blast messes with it and it won't read if it is very close. Close meaning withing 3 feet.
Re: Does the gun effect the fps
I probably should have asked that question a long time ago. Thanks
I probably should have asked that question a long time ago. Thanks
Re: Does the gun effect the fps
10ft minimum. The farther, the better; USGI velocities are clocked at 78ft.
10ft minimum. The farther, the better; USGI velocities are clocked at 78ft.
Re: Does the gun effect the fps
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">Short answer, yes.
If I read the question right, you're talking about effects during a single testing session.
As such, the barrel temperature and fouling state will bear on individual velocities.
Generally, for me, they tend to speed up when going from cold/clean to warm/fouled.
Greg </div></div>
Same here sometimes dramatically so. I now have a column on my notes for barrel temp. I use a good IR thermometer to measure the temp before each shot. So I can clarify later what I was doing when I tested the loads. The rifle I'm currently playing with has a noticeable impact shift when the barrel hits a certain temperature. I'm sure they all do but I'm one of those people that wants to know everything so when something changes or is going to change I can guess pretty accurately why.
I tend to use 15ft, measured every time I set it up and I made a little aluminum template and laser bore guide to make sure the bullet crosses as closely as possible to the same place each time, it's really quite exhausting
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">Short answer, yes.
If I read the question right, you're talking about effects during a single testing session.
As such, the barrel temperature and fouling state will bear on individual velocities.
Generally, for me, they tend to speed up when going from cold/clean to warm/fouled.
Greg </div></div>
Same here sometimes dramatically so. I now have a column on my notes for barrel temp. I use a good IR thermometer to measure the temp before each shot. So I can clarify later what I was doing when I tested the loads. The rifle I'm currently playing with has a noticeable impact shift when the barrel hits a certain temperature. I'm sure they all do but I'm one of those people that wants to know everything so when something changes or is going to change I can guess pretty accurately why.
I tend to use 15ft, measured every time I set it up and I made a little aluminum template and laser bore guide to make sure the bullet crosses as closely as possible to the same place each time, it's really quite exhausting
