Does 0.1 grain make a difference?

Downeast

Downeast

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I was working up a new load for my 6.5 Creed using Sierra's (142 HPBT) and H4350. I found a node between 41.0 and 41.3 grains of powder. The average V0 for 41.0 was 2721 and for 41.3, 2730. Group size was 1.14" (5 shots) at 200 yards for the 41.0 load and 1.5" for the 41.3. SD's was 6.52 for the 41.0 and 7.9 for the 41.3.

Anyway, my buds were telling me that I should load up 5 more rounds each at 41.1 and 41.2 and see if there is any difference. My argument is that we are talking 0.2 grains difference within the range of the two loads and that there are so many other variables that it makes no difference. Differing case capacities, bullet weights, ambient factors such as temperature and shooter error will negate the 0.2 charge difference.
 
Precision reloading consists of, a.) finding the optimum, and b.) reducing the variance. You know this already because you say so yourself.

Downeast said:
...we are talking 0.2 grains difference within the range of the two loads and that there are so many other variables that it makes no difference. Differing case capacities, bullet weights, ambient factors such as temperature and shooter error will negate the 0.2 charge difference.
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1.14" at 200 yards ain't so shabby. Nice job!

But why only between 41.0 & 41.3? Why not between the next lower charge (40.7?) and 41.0? You might find gold.

Unless the normal weight variance of a random lot of your bullets isn't good enough for you and you decide to weigh and segregate bullets, or weigh and segregate brass, or measure and segregate brass by case volume.

The rabbit hole is deep, my friend.
 
I started at 40.4 and worked up to 41.6 in .3 grain increments. I then graphed the velocities and the line leveled out between 41.0 and 41.3. I believe there may be something to this low SD's and accuracy. Lowest SD equaled the tightest group. I'm thinking that tweaking seating depth is the next step. Yes, the rabbit hole is very deep indeed. :confused:
 
In a word, yes it does, all other variables held constant. Try it and see but I would weigh every charge and be using a set of competition dies to insure variable control and uniformity.
 
Tim said:
If i were you, I'd set my powder thrower to 41.1 and have at it.
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I agree. If you really want to know the impact, you can go to any ballistics calculator on the internet and end your ES velocities and see what your vertical variance would be at various ranges. My guess in that you will not see any significant (>0.5 MOA) variation until you are out well past what most of us can shoot on the East Coast. Unless you are planning to shoot to 1000 yards, you have probably reached a point of diminishing return.

Time to cease load development and time to start chasing the the lands.
 
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I find that it's the percentage of variance, so .1 of 10 grains is 1 percent variance, totally acceptable even for precision stuff.

Most precision rifle rounds use more than 10gr of powder anyhow. So that leaves pistol -

.1 of 4gr is 2.5%, which is fine for pistol rounds. Perfectly fine for my usage.
 
Unless you are using a very nice analytical balance, the margin of error for the weight observed is right around 0.1gr or possibly greater

As others have stated it's a DEEEEEEEP rabbit hole to go down.

There is a reason the Prometheus powder trickler and scale exist and sells for $3800 ;)

http://www.prometheustoolcorp.com/

6.5 Creedmoor data has been ~41.3gr of H4350 under a 140gr bullet for about 6-7 years now.
 
This is .1 of a grain. When loading 40+ grains I really do not see that would make that much of a difference (for me). Like Charlie said, you are going to reach a point of diminishing returns. I would think once a brass casing would make a bigger difference in pressure.
.1 of a grain.jpg
 
Thank you, thank you, thank you!

But they make a Prometheus powder trickler and scale..for only $3,800? You worthless scum! Holding out on me the whole damn time. You sorry bastards! :D
 
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It can, in theory, however there are about 9 other factors, variables and considerations that make that difference demonstrable or not.
Eliminating variable by variable to get down to each specific item that you see a difference in down range is no short task. Particularly in precision long range shooting.
 
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When are you proofing your load to this level...5 rounds is really nothing..it's only 5 data points...run 10 at least.

Neck tension has a great effect than 0.1 grain
 
Bunsen said:
Unless you are using a very nice analytical balance, the margin of error for the weight observed is right around 0.1gr or possibly greater

As others have stated it's a DEEEEEEEP rabbit hole to go down.

There is a reason the Prometheus powder trickler and scale exist and sells for $3800 ;)

http://www.prometheustoolcorp.com/

6.5 Creedmoor data has been ~41.3gr of H4350 under a 140gr bullet for about 6-7 years now.
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Auto trickler delivers the same ball park of performance...not inside the diamond but ball park. Can load to 0.00 of a grain.
 
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MDof2 said:
I've got a bench rest buddy who loads with one and it's religion changing. The accuracy is literally down to the kernel.
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Yup, I have one of the first ones when it was RCBS trickler.. I want to get the auto thrower but I've thrown so much money to Adam's product since the start. Wish he offer a slight discount for the guys that been with him since conception.
 
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