Chrono results question.

[JimJams]

I've got some results for my first test of home loads. My 7.62 results max 2806 fps min 2608 avg 2725 And .223 max 2377 min 2200 avg 2325. 10 rounds each trial. Is this spread reasonable? Regards jj

[dicehorn]

JJ - unless your chronograph is suspect, I would say around a 200 fps spread on both calibres is not good. People using a chronograph are usually looking for a spread of no more than 40 fps. It could of course be that just one round was low and one high - if you were to deduct the lowest and the highest then divide by 8 how dramatically would that effect spread. Bear in mind the SD (standard deviation) is the all important figure.

For normal live quarry out to say 200 yds your figures are not too concerning, however at extended ranges I would predict accuracy will fall off.

[JimJams]

Hmm. I thought they looked a bit wide. The 7.62 session showed a sd of 82.5. It's the only one I recorded as I was going to research what it meant. Is it an indication of quality? Thank you for your comments. I'm New to reloading and find it totally absorbing. JJ

[tacfoley]

What are your loads, and what bullets are you using? Are all the cases the same in each calibre? Is there any particular reason why your .223 is so low to begin with? Most .223 hovers around 3000fps and up. Are these long-range target loads or for backyard plinking?

Information is pretty thin on the ground here.

tac

[angrybear]

First thing I'd say is put a dozen factory rounds through it & see how they compare, you might be surprised.

Don't get hung up on the ES or SD purely as numbers, only as a % of the average,

for your 7.62
ave 2725fps - max fps is +2.9%, min fps -4.2%, SD is 3% looks a bit better in those terms doesn't it .

[Randy Bohannon]

The ES and SD numbers are certainly plausible, if that is the question.

the last box of privi 243 ammo I chrono'd showed similar numbers.

getting the ES down is primarily a function of powder choice and how consistently that powder is ignited.

having said that for under 300 yards ES is not very important

[dannywayoflife]

Depends on useable. If your target shooting and want to take it seriously then they are wholely unacceptable.... If they are for 200 and in hunting your fine.
My target loads have an es of 18 and an SD of 8 from memory

[Randy Bohannon]

Depends on useable. If your target shooting and want to take it seriously then they are wholely unacceptable.... If they are for 200 and in hunting your fine.
My target loads have an es of 18 and an SD of 8 from memory

Fair enough Danny, the lower the better but a velocity difference of 100 fps, assuming adjusted zeros, leads to a difference in drop of around an inch at 300 yards.

Ok, not great for bench rest or F class but hunting and on a NRA target it doesn't seem to make too much difference.

[dannywayoflife]

If you were shooting seriously at targets would you accept that mate?? I know I wouldn't!

However regarding the rather large es and SD from the OP, what kind of chrono did you use? As that's a very large difference.

[Randy Bohannon]

If you were shooting seriously at targets would you accept that mate?? I know I wouldn't!

However regarding the rather large es and SD from the OP, what kind of chrono did you use? As that's a very large difference.

Absolutely and to be fair I wouldn't accept that for hunting ammo Danny but for hunting I would be ok with it.

[sarge4318]

So how do they shoot on paper? Do they group nicely?

If they do, does any of this matter?

[dannywayoflife]

So how do they shoot on paper? Do they group nicely?

If they do, does any of this matter?

At short range no it wouldn't matter but past a few hundred yards on small targets yes it will matter

[Elwood]

My guess is that they were put over the chronograph from a clean barrel? if so this can increase your ES and SD by twice the amount.

Fire two shots to foul the barrel before trying to get any useful data on group size or chronograph figures.

[sarge4318]

So how do they shoot on paper? Do they group nicely?

If they do, does any of this matter?

At short range no it wouldn't matter but past a few hundred yards on small targets yes it will matter

What I was trying to get at was do they group at the distance(s) you want to shoot them at?
If they do what you want, at the distances you want, does it matter what the ES, SD or MV is?

I have seen it many time where a shooter will try to reduce the ES or SD to the smallest possible even though they were hitting the bull every time just because they believed that a good round had to have the smallest ES, SD etc. or their mate was getting a much higher MV than they were getting so they tried to fix something that wasn't broken.