Loading coincidence?

nvbroncrider · Nov 23, 2011

When I shoot my test loads I've noticed that I will normally get a grain or grain and a half spread that is much more consistent then the rest. Just wondering if anyone else has noticed similar results or if its just a coincidence. I normally start at the low end in the book and go half grain increases up to 2 or 3 grains above book max as a start and stop when I see pressure. Sometimes I must go higher depends on the rifle.

DrMike · Nov 23, 2011

That is a pertinent observation that tends to hold true throughout the range of metallic cases for which most of us load. I usually aim for one to one and a half percent increments. Usually, one of those will stand out as the most accurate load. When you load in smaller increments, you will witness a tight range in which accuracy is noticeably improved.

onesonek · Nov 23, 2011

Yep,,,, just the burn rate, pressure curve, harmonics, all comming together in that rig finding a sweet spot..

nvbroncrider · Nov 23, 2011

This is what happens when a man and his thoughts can think for 12 hours on end in silence for 7 nights in a row. Next the powderless rifle that has no recoil or noise but propels a 160AB @ 3500!!!

Antelope_Sniper · Nov 25, 2011

NV, not only is that normal, that NODE you describe is what you are looking for when reloading.

In some rifles the groups will shrink as your powder charge goes in one direction, to a point, then begin to open up again.

Others just have this one point where they turn into bugholes.....

Each rifle is different, so the only way to find out is to shoot it!

DrMike · Nov 25, 2011

Actually, I've had nodes that were exceptionally precise. Moreover, you will observe a similar phenomenon with seating depth. Again, I have witnessed some that demanded incredible precision for seating depth.

nvbroncrider · Nov 25, 2011

I just never thought to put 2 and 2 together. I was looking back at a few targets I shot when i was playing with my 70gr Bt in .243 and i was shooting .75 to 1 inch groups with it when i selected my 48 gr load and I pulled out the target I fired my test loads at and it just stuck out like a sore thumb and I asked myself why I loaded those at 48 instead of 42. I guess that's just your efficency curve. I haven't played enough with loads or really cared that much before. I always thought an inch was good, but now that I have the time money and my own 425 yd rifle range I'm getting to play more than in the past.

Antelope_Sniper · Nov 25, 2011

Mike, I have one rife where .005 in seating length is the difference between 1" groups and .25" groups.

Darn think is as finicky as my wife!

DrMike · Nov 25, 2011

AS,

I finished working up a load that was rejected by the customer because it was just that persnickety. He didn't believe he could make his ammunition that precise. It gave me one to one and a quarter inch groups, until the last 0.010 inch when it shrank to 0.200 inches. The group was reproducible, but he wanted a better group. Eventually, by changing bullets, I found a good load that gives him 0.090 inch groups and holds for a charge variation of 0.50 grains. These rifles can be finicky, as you point out.

Win_94 · Jan 5, 2012

When load developing I use the Audette Ladder Test. The "node' spoken of in this thread will show-up when shooting the test. I can usually find a good load in less than 10 shots.

Here is my latest Audette Ladder Test target using the Eddystone US model of 1917.

That is the best load I've ever developed so far in any rifle, it is a shame I can't use it since the bullet's ballistics do not jibe with the sight graduations. It is only good for 300 yards or less since it shoots 12 inches high at 400 yards, then ever increasing heights, as does the distance.