Thread: Testing a conventional approach to load development

Originally Posted by Micky Duck

That's why I dual load.... Or at least carry a few of load that is better than others. For run of the mill stuff I'm happy with run of the mill loads.

Yeah, I definitely carry subsonic and supersonic for the 30/30.

Originally Posted by Hunterdave

Good enough for what your doing sure but that can vary quite a bit. Whats good enough for someone at 200m might not be good enough for someone else that wants to stretch out further

All the more important to really understand then, isn't it

So I have a box of 68gr Hornady BTHP Match .224" bullets on the shelf. There are 85 bullets. I don't know where the other 15 went, but the box has been there a long time.

I decided to tune up a load with these so I can use them.
CCI 450, some ADI brass FL sized.
2206H - book max of 26.0gr listed as compressed and 3069fps from a 24" bbl. I'd expect maybe 2950 from an 18" at that load and pressure. Loaded just touching the lands.

Loaded 6x sets of 3rd, from 24.5gr up to book max.

Here's the results:


24.5: 2876fps avg, SD 6.7, ES 16.2, group 0.428MOA
24.8: 2926fps, SD 10.3, ES 22.2, group 0.897MOA
25.1: 2950fps, SD 5.1, ES 12.5, group 0.760MOA
25.4: 2999fps, SD 11.3, ES 25.1, group 0.523MOA
25.7: 3036fps, SD 11.3, ES 28, group 0.481MOA
26.0: 3069fps, SD 17.7, ES 42, group 0.808MOA

Based on book velocity, I'm probably hitting SAAMI max pressure about 25.1 - 25
4 grains. I expect the ADI brass is a bit thick and I certainly wouldn't load up to 26.0 as the load was becoming heavily compressed.

In the interests of selecting the best load to tune, I think it's 24.5gr - after all, it has the smallest group and a nice low SD/ES.

So following the seating depth tuning method, I loaded 6x 3rd sets of 24.5gr, in 0.003" deeper increments. Not repeating the same depth at just off the lands - so that's a 7th sample. There's a functional window for any bullet in real life, and with this case/powder/bullet combo it starts to get pretty crunchy as the OAL shortens up. I could keep going with more loads at a shorter OAL - but let's see how these tune up.

1.867 - 1.852 CBTO.

Here are the results:



So I have a good tight group at 1.861" CBTO. It's also a nice group at .003 longer than that. Is it a node? Have I tuned a good load up?

CBTO/VelocitY AVG/SD/ES
1.870, 2876, 6.7, 16.2
1.867, 2866, 4.9, 11.7
1.864, 2857, 12.5, 29.5
1.861, 2867, 10.6, 25.9
1.858, 2858, 10.0, 23.2
1.855, 2862, 19.0, 42.8
1.852, 2854, 3.0, 6.6

So - what now?

Can't wait for the first bite . . .

Originally Posted by Tentman

Can't wait for the first bite . . .

Genuinely - advocates of tuning - which load do you think is the best and the worst ? Should I do any further tuning? What can I expect in the future?

I've fired 38 (don't ask about those 2) of my 85 bullets - so I have 47 left.

Seriously, with only 47 left, why don't you load them all at 1.861 and go gather some meat?
Life's too short.............

Originally Posted by gimp

So - what now?

You pick the best group, and the worst group and load up 10. Or even better 20 of each, and get back too us.

I’d love to see you load up 10 each of the “worst” or “best” four lengths and shoot them as two 3 shot groups and one 4 shot group and show those results as individual groups for each length, then show them as a combined 10 shot group.

1.861 should continue to print those nice tight groups if the tuning theory is correct.

Originally Posted by McNotty

I’d love to see you load up 10 each of the “worst” or “best” four lengths and shoot them as two 3 shot groups and one 4 shot group and show those results as individual groups for each length, then show them as a combined 10 shot group.

1.861 should continue to print those nice tight groups if the tuning theory is correct.

^^
This would be great to see.

Which seating depth would you pick as the worst? Clearly got some votes for 1.861" CBTO as the best.

10 rd each of 2 best/2 worst

or 20rd each of best, worst ?

I'm leaning towards the latter as 10rd groups should be expected to vary in size by + or - 40% from the average, and the MR will be less accurate than a 20rd measurement

'Load development' is a hobby in itself.

Got told by someone that 'cloverleaf was not good enough, one hole for 3-5 shots or nothing'

I asked them how many BR comps they were entering and winning as those results would definately place.

Silence...

Originally Posted by gimp

Which seating depth would you pick as the worst? Clearly got some votes for 1.861" CBTO as the best.

10 rd each of 2 best/2 worst

or 20rd each of best, worst ?

I'm leaning towards the latter as 10rd groups should be expected to vary in size by + or - 40% from the average, and the MR will be less accurate than a 20rd measurement

Let’s get some close to solid data then. 20 each of the worst and best. Use the longest length load as the worst.
I’ve been wanting to do this for ages but I just can’t find the time with two little terrors ruling my existence.

Shortest OAL you mean as the worst? 1.852 CBTO. 0.895MOA group