What do you make of this?


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exbiologist
May 30, 2010, 07:21 PM
So I recently learned how to conduct an optimum charge weight test/pressure ladder/whatchamcallit. I decided that would be a good thing to try and had been wanting to do some more load development with the 130 Accubond in my .264 Win Mag. Figured it would be a good deer load and should work well for cow elk.
Yesterday was pretty dang windy here in Colorado, but I'm not certain the wind was to blame. Previously, I tried several powders and had been pretty happy with the velocity with 66 grains of Win 780 with the 130 Accubond. The only group I ever shot with it was 0.6 MOA, 3 shots at 100. But for whatever reason, I left that load alone and never played with it again. Velocity was around 3250.
This is from a year ago and why I tried this combo again:
http://i392.photobucket.com/albums/pp5/richman_mark/P1040765.jpg
So yesterday I load up 3 rounds each around in half grain increments around 66 grains: 65.5, 66, and 66.5. I then load up .1 grain each for 11 total shots from 65.5 to 66.5 to see shoot a ladder group.
I don't know what to make of the results:
65.5 was around 1.6 inches and a bit of a flier to the left (20 mph wind was left to right), the two closest holes were were about an inch apart.
http://i392.photobucket.com/albums/pp5/richman_mark/P1040764.jpg
66 was a little larger at about 1.8 inches with two of the holes within an inch, and again a flier to the left by nearly an inch (winch blowing to the right).
http://i392.photobucket.com/albums/pp5/richman_mark/P1040769.jpg
66.5 was about 2 inches with 2 touching and 1 1/2 inches to the left.
http://i392.photobucket.com/albums/pp5/richman_mark/P1040768.jpg
Then I did the ladder group, which is incredibly hard to decipher. It looks to me like there is a node around 65.6 or 65.7 grains, but it was totally inconsistent. I have no idea what to make of it.
http://i392.photobucket.com/albums/pp5/richman_mark/P1040770.jpg
I do not believe the wind played a big factor in the groups, as the .270 I was shooting did not suffer from the same problems. Thankfully, I've kept many of my targets from the last few years as reference. Sure enough those Accubonds had thrown fliers to the left before with both N165 and 780, but no other bullet had done so to a meaningful degree before.
http://i392.photobucket.com/albums/pp5/richman_mark/P1040766.jpg
http://i392.photobucket.com/albums/pp5/richman_mark/P1040767.jpg
Next problem, what appears to be the making of a decent accuracy node puts velocities down into the mid to upper 3100 fps range, which is not acceptable. That's .270 country, not a .264. 3250 to 3300 is my goal with this load. Book max is 67.0, and that'll do 3400, but the pressure signs are not acceptable to me. This gun and I are capable of consistent half inch groups with good loads. On good days, I'll get the occasional group between 1/3 and 1/4 MOA with 100 grain Ballistic Tips ( my antelope load).
So what the hell do you make of all this?
What do you blame for the fliers to the left? Hard for me to blame anything but the bullet.
Do I need to try a new powder also? It doesn't seem like I can get the accuracy and velocity combination that I am after with this pair. Use something a little slower, like RL 22, MagPro, 7828 or N165? A lot slower, like H1000, Retumbo, Magnum, RL25 or US869?
Should I just call a do-over and do it again on a calm day at 200 yards for a little more separation?
Do I need to be shooting 5 shot groups to find any real differences?
Not sure what my next step should be here.

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Walkalong
May 30, 2010, 07:43 PM
Hard to shoot in the wind, and even harder to shoot 6's over and over, regardless of conditions. ;)

Yes, try it on a calmer day again. :)

NCsmitty
May 30, 2010, 08:33 PM
Working up loads in the wind will only lead to frustration and leave you wondering if it's the load, the rifle, or yourself. Leave it for another day, and a do over.
When I try to finalize a set, I always use 5 shot groups so your not dealing with a questionable triangulation. 5 shot stats make more sense out of the bench time.



NCsmitty

Kawabuggy
June 1, 2010, 06:45 PM
May I ask at what distance did you perform the ladder test??? I was under the impression that the test should be done at 300 yards(+/-). It seems like they are grouping so closely together on the ladder test that you were not shooting out far enough to see the variance in the load possibly.

dakotasin
June 2, 2010, 01:32 AM
agree w/ kawa... i think your ladder was shot too close. the longer the range the more meaningful the results, but you've got to be able to account for the wind.

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