Velocity Spread.....what is acceptable?

varminter .223

Active member
Getting about 175ish max spread on my 22 Nosler. Mid 3400s to low 3600's with Rem 7.5s and cfe 223 metered on chargemaster. Mixed number of firings on brass. What is to be expected? Shots will never be over 300 and very very few if any over 200. Probably a non issue but I like things to be right.

Looking at my Varget data and they appear to vary up to 150ish.
 
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That's a lot of spread. Are you sure your crony is ok? Varget should be better than that. Try different primers if you're convinced the crony isn't at fault.
 
It also may be the charge master.

Try some by hand to eliminate that as a reason.

I used to use a beam scale, that measured at .1 and when i went to a scale that showed .02 difference, I saw really quickly that getting that kind of difference, and changing scales brought my SD down using varget to a SD of 10.
 
No way a Chargemaster alone would cause that big of a velocity spread.

At least not in a bolt gun. I haven't chronoed any AR loads in a long time so I really don't remember any of my SD's.

I think I'd suspect the chronograph first.
 
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Originally Posted By: varminter .223I am gonna dispense about 10 charges this evening and weight them on a 10 10.

They should all fall within the .1 grain according to RCBS specs.
 
Keep your dispenser unplugged and don't coil the cord. Calibrate every time you turn it on. Weigh 3 powder loads individually, then pour them all out into the pan and devide the total by 3. Try 5 loads or 10. Is it right? Double check on a beam scale.

It's probably the chronograph. I borrowed a chrono once that was complete garbage. It drove me crazy with fluctuations like yours until I fired some standard velocity 22lr and realized the chrono was whack. It's possible it wasn't set up correctly if yours has sun shades and all that.
 
It a cheapy caldwell. I use the sunshades but shoot in the shade. I have not read the instructions but some shots blow the sunshades off and I've shot without replacing tbem to finish out that string.
 
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With a 55 gr bullet and a 100 yard zero you will be 8.5(3600) low at 300. 10.1(3400) low at 300. If you zero at 200 you reduce the vertical dispersion to about .8 inch and drop is in the 5.5-6.5 inches at 300. So for short to moderate range the velocity differences don't should not be a major factor for most of us wind drift is a bigger problem.
 
Originally Posted By: varminter .223but some shots blow the sunshades off and I've shot without replacing tbem to finish out that string.

If the muzzle blast is blowing the shades off you have the chrono way too close to the end of the barrel.
I had the base model Pro-chrono for a while. I always set it up so that the bullet entered the screens at 15 feet from the muzzle. I never measured it exactly-just 5 long steps from the muzzle.
I always got consistent numbers and it never missed a reading as long as I had it.
And I always used it in the shade with the sunshades attached like you are doing.
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I moved graph to 15'.
22 nosler 33 cfe 223 55 bt's
group 1 3517 low
3560 high 43 dif
group 2 3486 low
3548 high 62 dif
6.5x6.8 bhw 29 8208 95 max 5 shots
group 1 2882 low
2899 high 17 dif
Guess I was giving my graph a headache.
Thanks again
 
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Good deal!
You should be plenty good for your 200-300 yard shooting.
If you want to cut it down a little more the easiest things to do, without spending a bunch of money, would be experimenting with different primers, starting with a new batch of brass, and annealing the brass to get more consistent neck tension.
It would be tough to improve on the Chargemaster as long as it stays within the .1 grain guarantee.
 
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