OCW: Do you like 3, 4, or 5 shot groups?

[Winny94]

I have 2 potential nodes im fleshing out. One range is somewhere in 41.3 - 41.9 and another in the 43.3-43.9 range. To really zero in, which option would you recommend?

.2 increments (4 groups of 3 shots = 24 total shots)
.2 increments (4 groups of 4 shots = 32 total shots)
41.3 | 41.5 | 41.7 | 41.9
43.3 | 43.5 | 43.7 | 43.9

.3 increments (3 groups of 5 shots = 30 total shots)
.3 increments (3 groups of 4 shots = 24 total shots)
.3 increments (3 groups of 3 shots = 18 total shots)
41.3 | 41.6 | 41.9
43.3 | 43.6 | 43.9

 

[Bc'z]

.3 increments, 3 shots.
After seating 5 shots to confirm.

 

[danny]

I like one shot groups because the measurements look better.

Danny

 

[Bc'z]

I like one shot groups because the measurements look better.

Danny

1 shot 1 kill

 

[JFrank]

1 shot 2 kills

 

[Ned Ludd]

Once I have narrowed in on the potential charge weight regions/nodes as you have, I typically use 0.1 gr increments to cover each window and 5-shot groups. 5-shot groups may be a little more informative statistically, even though 3-shot groups will usually tell you what you need to know. Where 5-shot groups really offer something more than 3-shot groups is in terms of the velocity data/statistics. Once you have identified the final load(s) you want to use, go back and "validate" them by shooting 3 to 5 5-shot groups to confirm that both precision and velocity remain consistent.

 

[Falfan2017]

I like 3 shots .1 or .2 increments. Thinking is if the first 3 aren’t all within .15” at 100 there’s no point in shooting more. Then if I get some in .1 to .15” load up a couple 5 shot groups to confirm.

 

[dmoran]

Unless your only going to use the load/ammo at short range, shoot at distance (at least 300-yds) and let the vertical dispersion indifference's tell you the truth of which is better, and where the node centers are.

 

[tomswede]

If .1 makes a difference it’s not a stable load. Three shots are good for sorting out bad loads. If a three shot load looks good, time to verify with groups with a larger number of shots to make sure that it’s not a fluke ( there are no fluke bad groups)

 

[Bc'z]

1 shot 2 kills

The Quigley

 

[pacificman]

I get fussy when doing a OCW test. As some have mentioned I will use 5 shots .2 or .3 grains depending on caliber.
Then seating depth ...then as Ned mentioned fire at least 3.. 5 shot groups to confirm a stable load and accuracy.
I will then check everything at 2 and 300 yards and more to confirm longer range accuracy. When done I will have
complete confidence in my rifle.

 

[6ShotsOr5?]

I have 2 potential nodes im fleshing out. One range is somewhere in 41.3 - 41.9 and another in the 43.3-43.9 range. To really zero in, which option would you recommend?

.2 increments (4 groups of 3 shots = 24 total shots)
.2 increments (4 groups of 4 shots = 32 total shots)
41.3 | 41.5 | 41.7 | 41.9
43.3 | 43.5 | 43.7 | 43.9

.3 increments (3 groups of 5 shots = 30 total shots)
.3 increments (3 groups of 4 shots = 24 total shots)
.3 increments (3 groups of 3 shots = 18 total shots)
41.3 | 41.6 | 41.9
43.3 | 43.6 | 43.9

It depends on how good my fourth and fifth shots were.

 

[JFrank]

Here’s a question
With all the rounds shot during OCW test then multiple rounds on seating test are you concerned with barrel life as you continue to stay in tune?
Just curious
J

 

[F Class John]

Hopefully this helps a little. It’s easy, repeatable and works.

I use the “Cortina Method” as seen here http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/. There’s lots of great information on the 100+ pages of the thread (personally I’m a bigger fan of the first 20-30 pages). Yes it’s five years old but the process is sound and solid and yields me and lots of others excellent results in the shortest amount of time without killing barrels every time. Here’s the first page takeaway from Eric himself.

Some of you have asked for more detailed instructions on how I do this. Here they are:
1. Find Jam by seating a bullet long on a dummy piece of brass (no primer nor powder) and apply die wax to the bullet ogive and record it's base to ogive length.
2. Chamber the round and close the bolt.
3. Snap the bolt open and measure the base to ogive measurement. If it is shorter than previous measurement, this is your jam. Do it a few times with different cases to make sure.
4. Load a known powder/primer/bullet combination. I load 4 of each powder charge in 0.5 gr. increments and seat bullets at jam - .020". I use one shot of each to get barrel fouled up and also keep an eye for max pressure at the same time. You can also use these rounds to break in a barrel if you are inclined to. If I encounter pressure on the hotter rounds, I will not shoot groups with the other loaded rounds and will pull bullets when I get back home. Do not shoot in round robin style because position and natural point of aim will be compromised.
5. Shoot 3 shot groups starting from lowest to highest. All groups are shot over a chronograph.
6. Examine target and find the place where consecutive groups line up vertically and ES is the lowest and speed increases the least from one group to the next.
7. Load to the middle of the powder node and do a seating depth test.
8. Load 3 shot groups starting from Jam - 0.005" all the way out to Jam - .040" in .003" increments.
9. When you find the seating depth test that shoots the best, load towards the longest side of the node to allow more room for throat erosion.
10. Final step is to load the new seating depth and load 5 shot groups in 0.1 gr. increments 0.5 gr. on each side of node (if pressure limits are not reached). This will cover an entire grain of powder and you will be able to pinpoint where the powder node starts and ends. In the summer, load towards the low end of the node, and do the opposite in the winter.

HAPPY SHOOTING!

 

[perry42]

5 shot groups.

perry42

 

[Bc'z]

Here’s a question
With all the rounds shot during OCW test then multiple rounds on seating test are you concerned with barrel life as you continue to stay in tune?
Just curious
J

I've been told a barrel is a consumable item, just like bullets and powder.
Our differences are
You shoot 600 br
I'm a hunter and casual paper puncher.
Now my question is this.
How many seasons will your barrel last once you've confirmed your load?
This will depend on how many matches you attend, and how much you shoot for practice.
Same goes for me.
I've tested 4 bullets in all of my hunting rifles and have settled on a combination that works in all.
Now if it takes 75 to 100 rounds to complete and confirm my OCW tests I've gone through
300 to 400 rounds. Add in casual shooting another couple few hundred rounds a year my barrels should last quite a while.
Now let's look at my 06 in particular.
Its 15 or 16 years old same factory heavy sporter barrel.
And we both know how it shoots.

 

[JFrank]

I said that yep”

Just speaking for myself , it takes 50-70 to get a load developed
I have 840 round count.006 throat erosion over that period so I like to test seating (chase the lands) regularly, that’s 20 or so plus 50-70 each match yada yada !
Divide the unit into the factor add the time equation
I give up

 

[Billy 30-06]

I like to shoot 5 shot groups @ 100yds when working up loads. Many times 3 shots are in one hole and the next is out of the group. I like to use a chrono when working up a load. With a case that holds 40 grs of powder I adjust the load .5grs at a time until I get a good group. Then I may adjust the powder .1gr to get to the velocity my barrel likes. I like to shoot 2 or 3 5 shot groups to prove a load and then go to 1000yds. A good barrel and load should shoot with in a .5gr charge range.
Billy

 

[JEFFPPC]

I have 2 potential nodes im fleshing out. One range is somewhere in 41.3 - 41.9 and another in the 43.3-43.9 range. To really zero in, which option would you recommend?

.2 increments (4 groups of 3 shots = 24 total shots)
.2 increments (4 groups of 4 shots = 32 total shots)
41.3 | 41.5 | 41.7 | 41.9
43.3 | 43.5 | 43.7 | 43.9

.3 increments (3 groups of 5 shots = 30 total shots)
.3 increments (3 groups of 4 shots = 24 total shots)
.3 increments (3 groups of 3 shots = 18 total shots)
41.3 | 41.6 | 41.9
43.3 | 43.6 | 43.9

I have a friend who is a statistical engineer. He convinced me several years ago I could do my load development with 2 shot groups. I told him nuts but being smart enough to realize he is smarter than I am I tried it. Works fine, I confirm at the end with a 5 shot group. Saves rounds down the barrel for matches. I have used this for 6 barrels in 6ppc, 6brx, and 6.5x47. If you have good bench habits it will work for you.

 

[JFrank]

If two shots suck then why shoot a third?