OCW - optimal charge weight

[dung8604]

Hey guys, ran across this article, and I found it pretty interesting. Had anyone seen/tried/believes in this method?

http://optimalchargeweight.embarqspace.com/ocw-vs-ladder/4529811360

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['ol shooter]

I think it has some merit.

[BLR81]

Hey guys, ran across this article, and I found it pretty interesting. Had anyone seen/tried/believes in this method?

http://optimalchargeweight.embarqspace.com/ocw-vs-ladder/4529811360

Sent from my Nexus 4 using Tapatalk 4

A sub moa rifle will have good pattern at 100 yds no matter what the load. So, yes, it will eliminate some of the wind affect, but there will be less vertical variations than say 300-600 yards. And, what you're looking for is a node (3 consecutive charge weights that group close together vertically). That way small variations in your powder drop when loading will have very little affect on your elevation.

Here's the deciding factor for me. Can you shoot a sub minute and a half group at 300 yds. If your not going to be consistent with your marksmanship at distance, your not going to get good and accurate results from a long range ladder test.

At 100 yds a one MOA rifle is going to have a very close spread vertically using even .5 grain increments. And, you still won't know if most of the best nodes are from the load or poor marksmenship by you. So, if you can't shoot consistent groups, do the round robin of 5 shot groups from 100 yds in 0.5 grain increments. But do it 2 or 3 times to verify your results. To reduce the number of loads you'll have to try, decide if you really need a max or near max load. If your not going to shot past 300-500 yds, just stick to the min to middle range. If your working up for long range like 1000 yds start in the middle and work up to max.

When I work up loads I do a 0.3 increment charges, and shot out to 300 yds. In most cases that 20-28 individual rounds, and I can usually find at least 2 nodes which group very close vertically. Then I do the OCW in 0.1 increment charges from the first load to the highest load in each node using 5 shot groups.

It takes a lot of time, and over 100 rounds. And, a lot of walking down to the 300 yd target.

[dung8604]

A sub moa rifle will have good pattern at 100 yds no matter what the load. So, yes, it will eliminate some of the wind affect, but there will be less vertical variations than say 300-600 yards. And, what you're looking for is a node (3 consecutive charge weights that group close together vertically). That way small variations in your powder drop when loading will have very little affect on your elevation.

Here's the deciding factor for me. Can you shoot a sub minute and a half group at 300 yds. If your not going to be consistent with your marksmanship at distance, your not going to get good and accurate results from a long range ladder test.

At 100 yds a one MOA rifle is going to have a very close spread vertically using even .5 grain increments. And, you still won't know if most of the best nodes are from the load or poor marksmenship by you. So, if you can't shoot consistent groups, do the round robin of 5 shot groups from 100 yds in 0.5 grain increments. But do it 2 or 3 times to verify your results. To reduce the number of loads you'll have to try, decide if you really need a max or near max load. If your not going to shot past 300-500 yds, just stick to the min to middle range. If your working up for long range like 1000 yds start in the middle and work up to max.

When I work up loads I do a 0.3 increment charges, and shot out to 300 yds. In most cases that 20-28 individual rounds, and I can usually find at least 2 nodes which group very close vertically. Then I do the OCW in 0.1 increment charges from the first load to the highest load in each node using 5 shot groups.

It takes a lot of time, and over 100 rounds. And, a lot of walking down to the 300 yd target.

There's some great advice here and I appreciate it, but that's not what the author is saying, really. OCW, from my understanding, means that there is a 'range' (not a node) in which your loads will perform nearly the same, so if you're off by a bit on your charge, or your bullets aren't all seated identically, it has less affect on your accuracy.

I posted method vs a traditional ladder, but perhaps I should have posted this instead

http://optimalchargeweight.embarqspace.com/ocw-overview/4529824091

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[wtkaiser]

With some shooters, it's a wide range. I shoot from 6 gr of BE up to nearly 30 gr of h-110, depending on the load, and I miss equally well with all of them.

[CK_32]

It's the new ladder testing.

Just about everyone and anyone is doing it. Seems to hold well. Till something new and better comes out actually.


I'm going to try it this weekend for my varget loads. Well see how it goes

[BLR81]

There's some great advice here and I appreciate it, but that's not what the author is saying, really. OCW, from my understanding, means that there is a 'range' (not a node) in which your loads will perform nearly the same, so if you're off by a bit on your charge, or your bullets aren't all seated identically, it has less affect on your accuracy.

I posted method vs a traditional ladder, but perhaps I should have posted this instead

http://optimalchargeweight.embarqspace.com/ocw-overview/4529824091

Sent from my Nexus 4 using Tapatalk 4

We may be saying the same thing just in different words. My nodes are a 'range' of load weights that perform the same. If say I start at 43gr and increase by 0.3 for each load, I may have a vertical gap of 1" between loads. If say 45.0, 45.3, and 45.6 group vertically within 1", that is a 3 shot group that's as tight as the average single load deviation so that is a node.

Now, I have my starting point. I'll OCW 5 shot groups from 45.0-45.6 in 0.1 and try to find the most accurate groupings. So if 45.4 produces the best sub-moa group of the node, that will be my target load. And, I'll know that if I'm 0.2 plus or minus that target weight, that my vertical spread is still going to be extremely close since the original 0.7 grain node was within 1" vertically.

Also, once I've found the optimum charge weight for my rifle, I'll start to experiment with seating depth. When I start, I usually start with the bullet seated .020" off the lands to take the seating depth out of the high pressure equation when I get near max loads.

Now I'll shoot a similar round robin 5 shot groups with the bullet seated deeper and longer in .005" increments to find the best OAL for my optimum charge weight.

But, the main point is that no matter what distance you run your test, 100 yds, 300 yds or even 600 yds, your marksmenship skills can skew the results. So if your very good you'll get better results with longer ranges. If your not as good, use a stead rest at 100 yds, but run the test more than once to eliminate human error.

[dung8604]

We may be saying the same thing just in different words. My nodes are a 'range' of load weights that perform the same. If say I start at 43gr and increase by 0.3 for each load, I may have a vertical gap of 1" between loads. If say 45.0, 45.3, and 45.6 group vertically within 1", that is a 3 shot group that's as tight as the average single load deviation so that is a node.

Now, I have my starting point. I'll OCW 5 shot groups from 45.0-45.6 in 0.1 and try to find the most accurate groupings. So if 45.4 produces the best sub-moa group of the node, that will be my target load. And, I'll know that if I'm 0.2 plus or minus that target weight, that my vertical spread is still going to be extremely close since the original 0.7 grain node was within 1" vertically.

Also, once I've found the optimum charge weight for my rifle, I'll start to experiment with seating depth. When I start, I usually start with the bullet seated .020" off the lands to take the seating depth out of the high pressure equation when I get near max loads.

Now I'll shoot a similar round robin 5 shot groups with the bullet seated deeper and longer in .005" increments to find the best OAL for my optimum charge weight.

But, the main point is that no matter what distance you run your test, 100 yds, 300 yds or even 600 yds, your marksmenship skills can skew the results. So if your very good you'll get better results with longer ranges. If your not as good, use a stead rest at 100 yds, but run the test more than once to eliminate human error.

So once you've found your range, how much better do your groups get when you start using 0.1 grain increments to dial it in?

Say you've found your OCW, then you've found the specific charge that your rifle likes. What is the difference between these two groups at the high and low end of your range?

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[CK_32]

Very small amount of improvement per .01 gr adjustments. Some guys are good with .03 gr till they find a good node and leave it at that. But if you need that extra bit by all means go for it. I felt that in my $1300 rifle it wasn't needed. But if I had a $3,800 Gladiolus or something higher end I might do .01 tweaks to get that perfect load

Also just so you know your rifle will have about 3 different nodes. Say like 41.2gr, 44.4gr and 46.8 gr. But some prefer the middle or lower node to increase brass and barrel life also some lower velocities for shorter ranges cause HV isn't needed as much.

But for long range that limits the bullet at slower speeds so some guys like the higher node to get full performance and higher velocity to stay more stable at longer range at the expense of shorer barrel and brass life due to higher pressures and velocities. But to some its minimal for the gain others it's not worth it.

[mark501w]

I like setting up for each individual target.

[dung8604]

Very small amount of improvement per .01 gr adjustments. Some guys are good with .03 gr till they find a good node and leave it at that. But if you need that extra bit by all means go for it. I felt that in my $1300 rifle it wasn't needed. But if I had a $3,800 Gladiolus or something higher end I might do .01 tweaks to get that perfect load

Also just so you know your rifle will have about 3 different nodes. Say like 41.2gr, 44.4gr and 46.8 gr. But some prefer the middle or lower node to increase brass and barrel life also some lower velocities for shorter ranges cause HV isn't needed as much.

But for long range that limits the bullet at slower speeds so some guys like the higher node to get full performance and higher velocity to stay more stable at longer range at the expense of shorer barrel and brass life due to higher pressures and velocities. But to some its minimal for the gain others it's not worth it.

Wow, didn't realize there were three nodes, most of the info I read only indicated two.

I think what I will do, since I'm not a great shot, is find the OCW at 100 yards, and then practice with that until I am a good shot. I think that wind affects me way too much when shooting, and I don't think it's my reloads...

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[BLR81]

So once you've found your range, how much better do your groups get when you start using 0.1 grain increments to dial it in?

Say you've found your OCW, then you've found the specific charge that your rifle likes. What is the difference between these two groups at the high and low end of your range?

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It depends on the weapon. I've done it with a 1941 built Swiss K31, and had a spread of from 1 1/4 moa down to 3/4 moa. My LR tactical in 260 Remington was 1/2 moa down to 1/3 moa. That's why having a good starting point before you shoot groups is so important. That 260 shoots sub-moa with factory ammo at 100 yds.

If you're going to run an OCW where the difference in min and max load is 6 grains, even doing 0.5 grain increments your talking about 13 groups. One bad shot on your part can eliminate a whole area where your node may be because the majority of the loads will group sub-moa. Say the best node for your rifle in 45.3 to 45.9 grains. If you shot 0.5 grain increment and shoot at 45.0, 45.5, and 46.0 grains, one or two bad shots on the 45.5 groups may fool you into eliminating that whole range.

Depending on the powder you're using you can have quite a wide range to test. Using a slow powder like H4350, I've had as many as 26 different loads. In 26 different powder weights I've had as many as 3 separate nodes.

For the long range target rifles, I use the load near max for matches, and the middle node for practice. Less wear and tear on the rifle and me, and I'm practicing my skill and not trying to train the rifle to shot hot loads. The rifle shots the same, only the scope dope is different.

[Whiterabbit]

At a basic level, it's just a round robin ladder test (repeated). Uses more components, and tells you IMO more useful information.

It's worth doing. But I do things like most folks in the rest of the nation (rather than calguns) and use charge increments of over .1 grains as I work up. I don't shoot cartridges that use less than 5 grains of powder.

[BLR81]

Coincidentally, one of my favorite YouTube sites just posted this about OCW. http://www.youtube.com/watch?v=8hzcxytpKWU

[LynnJr]

At a basic level, it's just a round robin ladder test (repeated). Uses more components, and tells you IMO more useful information.

It's worth doing. But I do things like most folks in the rest of the nation (rather than calguns) and use charge increments of over .1 grains as I work up. I don't shoot cartridges that use less than 5 grains of powder.

I agree that the OCW is simply a round robin Ladder Test but feel it uses way too many rounds for my liking.

On a proper "Ladder Test" your increments would not be 0.1 grains they would be 1% of your charges weight.
On a small cartridge like the 6BR you would use 0.3 grain increments.
On a medium cartridge like the 300 Weatherby you would use 0.7 grain increments.
On a large case like the 50 BMG you would use 2.5 grain increments.
Once you find an area without vertical you would shrink your incremental size so you can find both ends of the node and center things up.