Took a recently rebarreled 22-250 to the range for the first time today with 7 loads. Used dn ocw approach, 1 round every two minutes cycling through the various loads. Started with 33gr and in 1/2gr increments went up to 36gr. Powder was imr4064, bullet was sierra 55gr hpbt. All brass was new. Not exactly thrilled with the results but hoping I can tighten them up with some seating depth changes. Barrel is 1:12 so may try some 60 or 69gr. Anyway I'm thinking the best ocw loads are 35-35.5gr.
Ocw results .. Thoughts?
- Thread starter 1stmar
- Start date
jwrowland77
New member
If this was me, I'd work shoot again, 33.5, 33.8, 34.1, 34.4, 34.7. I like the 34gr the best
All those groups are statistically, in my opion, too close to make any decision as to what load is the most accurate. A 3-shot group has about 20 to 25 percent of representing what all shots will group into.
They do show that a few grain spread of charge weights makes the same size groups at that range as you shoot them.
They do show that a few grain spread of charge weights makes the same size groups at that range as you shoot them.
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My understanding of using OCW is for center of group impact movement, not group size. So draw a line connecting the 3 shots at each powder grouping, determine the approximate center, then compare how the various group centers shift. Pick the load that is bracketed by similar locations as they have similar barrel vibrations.
Then start making adjustments for group size at that powder loading.
I also concur with Bart that 3 shot group size tells me little to nothing about how that load will group. Try some 10 shot groups and compare and you will quickly find how little the 3 shot groups mean.
Then start making adjustments for group size at that powder loading.
I also concur with Bart that 3 shot group size tells me little to nothing about how that load will group. Try some 10 shot groups and compare and you will quickly find how little the 3 shot groups mean.
It looks to me like loads 2, 3, 4, 5, and 6 are all putting bullets in the same area of the target, wouldn't that be your accuracy node? If so then charge weight #4 should be where you start messing with seating depth to really dial in your groups.
Did you notice on groups 1, 3, 4, 5, and 6 that you have 2 shots very close to each other and the a third shot pulled? I'm wondering what is causing that?
Did you notice on groups 1, 3, 4, 5, and 6 that you have 2 shots very close to each other and the a third shot pulled? I'm wondering what is causing that?
Brian Pfleuger
Moderator Emeritus
You're increments are too large. You should be using no more than 0.7-1% of maximum charge weight, that would be 0.4gr AT MOST and rounding down is better than rounding up. In other words, increments of 0.3gr would be most appropriate.
That said, the group center of 33, 33.5 and 34.0 are close to the same point.
Alas, you also ended 0.3gr below Hodgdon's max load. The standard OCW practice (for these charge weights) would be 0.3gr increments and ending 0.3gr above expected max load.
Your increments (starting from zero and unsure of pressures) should be 33.3, 33.6, 33.9, 34.2, 34.5, 34.8, 35.1, 35.4, 35.7, 36.0, 36.3, and 36.6. You only would be need 1 each of the first 3. Since you've already gone all the way up to 35.5, there's no need for those first 3 at all.
I suggest starting at 34.2gr and doing it again.
That said, the group center of 33, 33.5 and 34.0 are close to the same point.
Alas, you also ended 0.3gr below Hodgdon's max load. The standard OCW practice (for these charge weights) would be 0.3gr increments and ending 0.3gr above expected max load.
Your increments (starting from zero and unsure of pressures) should be 33.3, 33.6, 33.9, 34.2, 34.5, 34.8, 35.1, 35.4, 35.7, 36.0, 36.3, and 36.6. You only would be need 1 each of the first 3. Since you've already gone all the way up to 35.5, there's no need for those first 3 at all.
I suggest starting at 34.2gr and doing it again.
Allenj I did notice that, especially while shooting and it was not particular to the string so I'm not sure what it was. I did wait the same time between shots.
Brian if the shot groups have virtually the same poi after being triangulated, I'm not sure going to a smaller charge weight would yield anything different. Seems counter intuitive.
I'm going to clean the rifle and repeat based on your recommendations but I'm thinking I'll see similar results.
Brian if the shot groups have virtually the same poi after being triangulated, I'm not sure going to a smaller charge weight would yield anything different. Seems counter intuitive.
I'm going to clean the rifle and repeat based on your recommendations but I'm thinking I'll see similar results.
Brian Pfleuger
Moderator Emeritus
Larger charge weights allow you to jump over OCW sweet spots without seeing them. You used 7 increments where you should have had 9.
Notice that the 3rd and 4th groups are almost in the same spot and the 5th and 6th are almost in the same spot but the 4 aren't ALL in the same spot. That suggests to me that the true OCW charge range is in between some of those charges.