How much is 0.1 grain difference making to my accuracy

[roob]

Hi guys,

I'm using a manual powder thrower at the moment and it's sometimes dispensing 0.1gr more or less than I'm aiming for.

Is this to be expected?

How much is this likely to be effecting my accuracy?

It's doing what I need as I'm no pro shooter, I'm just wondering?

[Jack V]

Yes that's quite normal and if you are getting 1/10 of a grain accuracy then that is very good. Once you eliminate many of the other variables in re-loading , you will find that slight powder charge differences make no major accuracy difference that is easily detected on the target.

[brett1868]

Some of this would depend on the size of the load a well, 0.1 could possibly have an impact if your only throwing small loads for pistols but make no difference for larger rifle loads. The big gun takes 233Gr of powder so 0.1 +/- won't make a difference at all.

[roob]

The big gun takes 233Gr of powder so 0.1 +/- won't make a difference at all.

Should have said it's for my 7mm and my .22-250.

Nothing as huge as a 223gr load

[Gwion]

The big gun takes 233Gr of powder so 0.1 +/- won't make a difference at all.

Should have said it's for my 7mm and my .22-250.

Nothing as huge as a 223gr load

From my brief experience (only started reloading about this time last year) and also from info i have read, 0.1gr is a minimal change and wont make a difference if you choose a charge weight based around a moderate load with stable characteristics.

To illustrate. I have three nodes in my 223 where it shoots 0.7moa-0.5moa consistently. It has shot a few groups around 0.4-0.3 but not doable all the time (for me, anyway).
Anyway, the two lower nodes will shoot pretty similarly over a 0.4gr variance. So, 24.5 shoots ok 0.2-0.3gr above or below giving maybe 1moa instead of 0.5moa. Same with the mid load of 25.4gr, not too bad a few points of a grain over or under, just not as good as a consistent load. However, the third node is getting close to book max at 26.2. It shoots ok at 26.1 and 26.3 (still 0.7moa or better), but get to 26.4 and it starts shooting about 2moa+ and at 26gr it's 1.2moa, so it's more sensitive to consistent powder weight.

From my research, this is not entirely uncommon and more prevalent in smaller cases than larger ones, as mention by others.

Cheers.

[cavok]

Some of this would depend on the size of the load a well, 0.1 could possibly have an impact if your only throwing small loads for pistols but make no difference for larger rifle loads. The big gun takes 233Gr of powder so 0.1 +/- won't make a difference at all.

In my 9mm case for pistol use I load 7.4grns, this is what my press churns out, and I usually weight the 2nd or 3rd case, then 1 at 50 and then 1 at 100. The weight difference from my press using AP50 is always +/- .1 grn, that's the best it can do. When my 3 rounds are chronoed at the range it usually comes up 1300 ft/s, 1285ft/s or 1315ft/s. Hence as I load 7.4 then .01 means little. As others write, in my .223 using 22grns, .01 means even less. When shooting my Magnum .357, .01 grns means the difference between 1/2 ft per second faster or slower,
In a press producing 400/500 + rounds per hour it is advisable to check grn weight at the beginning, middle and end, nice to know its safe.

[bigfellascott]

It wouldn't concern me too much to be honest (hunting only here) may upset those who chase tiny little holes in paper but.

[brett1868]

My usual method of verifying how consistent I reload is measuring the "Extreme Spread" on the chronograph for a 10 shot sample. I generally achieve 20-40fps on the little gun and 30-50fps on the medium rifle, which isn't too bad considering their leaving the muzzle at 3990 & 2800fps. On the 338 you can see the data below. Accuracy is all about consistency.....

Series 1 Shots: 10 DTA 338 250Gr Hornady HPBT
Min 2788 Max 2834 85Gr AR2213SC
Avg 2806 S-D 15.2
ES 46

Series Shot Speed
1 1 2834 ft/s
1 2 2792 ft/s
1 3 2797 ft/s
1 4 2819 ft/s
1 5 2813 ft/s
1 6 2791 ft/s
1 7 2788 ft/s
1 8 2801 ft/s
1 9 2812 ft/s
1 10 2821 ft/s

[salate]

Yes that's quite normal and if you are getting 1/10 of a grain accuracy then that is very good.

+1

That's pretty good if that's the worst variation your getting.

[roob]

It wouldn't concern me too much to be honest (hunting only here) may upset those who chase tiny little holes in paper but.

Nah. Large clovers is more than enough for me

[roob]

On the 338 you can see the data below.

Thanks for the Chrony data Brett.