Chronographing load???

scott_r

scott_r

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I just purchased a chronograph and tested my favorite coyote load. Here is what I had for a 50 gr. VMAX with 26 gr. Varget and it was about -10 out.

3165 FPS
3091
3245
3186
3201

Why the huge spread of velocity? is this normal or did I not set the machine up right or something? The load is very accurate, printing 1/2 MOA at 100 yards. What can a guy do to get the velocity closer to each other.

Cheers!!
 
If it is accurate out to distance that will tell the tale. The speed discrepancy may show at 300 Yards in terms of spread. I think if it is accurate at longer distances than don't worry about the spread. But others will know more than me on this.
 
That is a huge variation in velocities. Do you use a Chrony brand chronograph? If so, lighting conditions can really cause issues with the readings. I am really liking my Magnetospeed, and not having variations due to lighting conditions is just one reason.
 
Where the sun is will have an effect on that chrony.

Are your shades in place proper?

SHooting line is proper through the sensors?

Chrony is about 12-15ft from the muzzle?
 
I actually had to set my Chrony up at 18- 20ft to avoid any errors when shooting my 7mmstw and 300RUM rifles. I could get away with less with my other rifles. And you need to shoot each shot through the screens at the same angle to get consistent readings. Even moving your shooting position very slightly can effect the readings. The Chrony units do work, but they can be irritating to use.
 
Im using a Caldwell chrony, only one I could find in Regina. Im a newbie with Chronographs,,,if they are very poor I may return it for some better like you have Stubblejumper.

I was out today and it was very bright, no clouds and I did get some error reading come up on the screen.

Machine was placed approx 10 ft from muzzle on a tripod.

Is there a certain time of day that works best or condition?

Cheers!!
 
it could be the brass
I checked the water capacity of 5 Norinco 223 brass last night and 4 of them were 30.3±0.1 grains while one measured 27.2 grains
This is a large variation.

edit: yes I did re-do the measurement to make sure
 
scott_r said:
Im using a Caldwell chrony, only one I could find in Regina. Im a newbie with Chronographs,,,if they are very poor I may return it for some better like you have Stubblejumper.

I was out today and it was very bright, no clouds and I did get some error reading come up on the screen.

Machine was placed approx 10 ft from muzzle on a tripod.

Is there a certain time of day that works best or condition?

Cheers!!
Click to expand...

I didn't use the screens at all on bright sunny days, and it seemed to help somewhat. I found times with the sun low in the sky to be the worst, and the problems were minimized the closer the sun was to being directly overhead. Days with a high overcast, but with the sun somewhat hidden seemed to provide the most consistent results of all. 10ft might be a little too close as is evident by the error indications. As I posted, the cheaper chronograph units like Chrony do work, but they are more effected by conditions than some other types.
 
legi0n said:
it could be the brass
I checked the water capacity of 5 Norinco 223 brass last night and 4 of them were 30.3±0.1 grains while one measured 27.2 grains
This is a large variation.

edit: yes I did re-do the measurement to make sure
Click to expand...

Using inconsistent brass can cause inconsistent loads, which is why I use better quality brass , normally Lapua whenever it is available in the chambering that I am using. The nice thing about this though, is that you can pick out a batch of cases with the same capacity to test your chronograph. If the large variation in velocity goes away, then get some better quality brass, if the variation remains, the brass isn't the issue.
 
stubblejumper said:
I didn't use the screens at all on bright sunny days, and it seemed to help somewhat. I found times with the sun low in the sky to be the worst, and the problems were minimized the closer the sun was to being directly overhead. Days with a high overcast, but with the sun somewhat hidden seemed to provide the most consistent results of all. 10ft might be a little too close as is evident by the error indications. As I posted, the cheaper chronograph units like Chrony do work, but they are more effected by conditions than some other types.
Click to expand...

The OP clearly stated Caldwell chrony.
That's not a cheap unit and I trust the readings.
Must be either the brass or the powder charges (or less likely the primers)
 
Thanks for the help everyone appreciate it.

Im guilty of using range brass lol..Typically I leave the chinese brass...Most of the stuff I pick up is Winchester and Hornady. I may have to pony up and buy some quality stuff like Lapua..Ive always wondered if Id get better groups with premium brass.

Cheers!!
 
scott_r said:
Thanks for the help everyone appreciate it.

Im guilty of using range brass lol..Typically I leave the chinese brass...Most of the stuff I pick up is Winchester and Hornady. I may have to pony up and buy some quality stuff like Lapua..Ive always wondered if Id get better groups with premium brass.

Cheers!!
Click to expand...

You can measure the case capacity with water and select say 20 cases that are really close.
Try to get perfectly weighted powder charges and use bullets that weigh less than half a grain lightest to heaviest.
Then try again :)
After all, we enjoy shooting and tweaking aren't we? :)
 
legi0n said:
The OP clearly stated Caldwell chrony.
That's not a cheap unit and I trust the readings.
Must be either the brass or the powder charges (or less likely the primers)
Click to expand...

Have you actually looked at the price of Caldwell chronographs? You can buy them for under $100 in the USA, and under $200 in Canada. As such, Caldwell chronographs are priced about the same as the Chrony units, so they are most definitely cheaper chronographs. Other than not having a folding housing, they are also set up very similar to the Chrony units, so it's quite possible that they suffer from the same problems as the Chrony units.

Im guilty of using range brass lol..Typically I leave the chinese brass...Most of the stuff I pick up is Winchester and Hornady. I may have to pony up and buy some quality stuff like Lapua..Ive always wondered if Id get better groups with premium brass.
Click to expand...

If you are mixing Winchester and Hornady brass, you can expect to see some fairly large variations in velocity, due to the varying case capacities. If you want consistent results, you should start out with consistent brass.
 
Last edited:
stubblejumper said:
If you are mixing Winchester and Hornady brass, you can expect to see some fairly large variations in velocity, due to the varying case capacities. If you want consistent results, you should start out with consistent brass.
Click to expand...

Now the hardest part of it.....finding new quality .223 brass in stock. Prophet River has zero .223 cases and nobody around my area has any. You can never win. Maybe I will take a trip to the Calgary Gun show and find some.

Cheers!!
 
your results 50 gr. VMAX with 26 gr. Varget and it was about -10 out.
Shot # FPS
#1 3165 13
#2 3091 87
#3 3245 67
#4 3186 8
#5 3201 23
Average Velocity 3178
Extreme Spread 154
Average Deviation 39.7
Standard Deviation 56.6
---------------------------------------------------------------------------
I has similar results with one of my first test loads (4895 -223 55g
mine was with range pickup all win brass

Extreme Spread 91
Average Deviation 31.8
Standard Deviation 38.2

Same rifle/ same bullet /different primer / different powder / Different brass (range pickups)
this powder measures better in my thrower
Extreme Spread 50
Average Deviation 17.3
Standard Deviation 22.4

that is why chronographs are a good thing ----> but are not a end all to finding a good load
but you can put 10 shots over one and find out if you need to change some thing

If you can get Standard Deviation to less than 12 you are doing great // less than 10 perfect:)

but you can get a Standard Deviation reading of less than 10 and have it keyhole at 100 ydsd:h:
 
scott_r said:
Thanks for the help everyone appreciate it.

Im guilty of using range brass lol..Typically I leave the chinese brass...Most of the stuff I pick up is Winchester and Hornady. I may have to pony up and buy some quality stuff like Lapua..Ive always wondered if Id get better groups with premium brass.

Cheers!!
Click to expand...

You don't need to spend $100 on 100 cases to get better results. I've had great results with winchester, remington, and hornady brass. Just use one brand at a time. Work up a load with hornady brass then keep using that. If you want to use a different brand then make a new load with that brass.
 
My 17REM provides outstanding accuracy and all I feed it is REMINTON brass.
LAPUA brass isn't available in this calibre but I don't need it either.
spend your money wisely !
 
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