OCW Load Development

[ndayton]

Looking to get some opinions on my OCW results. This is the first time trying this method shooting round robin 3 shot groups. Based off my limited knowledge it appears the lower charges seem to be the most forgiving but of course the tightest group is at max load (I know this test is not about group size).
No signs of pressure at max tested load.
Thanks for any input.

 

[ID_Matt]

What makes you say the lower charges are more forgiving? Also, hard to interpret anything without the velocities.

 

[ndayton]

What makes you say the lower charges are more forgiving? Also, hard to interpret anything without the velocities.

My understanding is this test checks for impact changes based on charge weight. Being that my groups impact roughly the same area at the lower charges led me to this conclusion.
Didn't want the variable with my magneto speed attached so no velocities.

 

[Pickettpuncher]

Here’s my analysis. And I think I know what you’re trying to achieve. Your load is trending down. I would suspect your first two groups are on a node and your last group is possibly the start of another node. Problem is the first bunch of groups aren’t like the last. How do you know you’re at max charge? Cause the book says so or because your next group has a sticky bolt, or your primers are showing signs. The question above with the velocity is on point as well. What’s the ES and SD? Personally, .03 is better than .04 or .5 difference in charge weights. Have you ran a seating depth test yet or you gonna do that next?

 

[ndayton]

Here’s my analysis. And I think I know what you’re trying to achieve. Your load is trending down. I would suspect your first two groups are on a node and your last group is possibly the start of another node. Problem is the first bunch of groups aren’t like the last. How do you know you’re at max charge? Cause the book says so or because your next group has a sticky bolt, or your primers are showing signs. The question above with the velocity is on point as well. What’s the ES and SD? Personally, .03 is better than .04 or .5 difference in charge weights. Have you ran a seating depth test yet or you gonna do that next?

Going off hodgdon's max listed, but I never hit pressure so there is room to go up.
I planned to do seating depth test after picking a charge weight.
Basing off others the plan was to find a flat spot and then test .1 or .2 changes in charge weight. around those numbers.
Like seating depth I was going to check velocity, SD/ES numbers after picking a charge weight

 

[Pickettpuncher]

Going off hodgdon's max listed, but I never hit pressure so there is room to go up.
I planned to do seating depth test after picking a charge weight.
Basing off others the plan was to find a flat spot and then test .1 or .2 changes in charge weight. around those numbers.
Like seating depth I was going to check velocity, SD/ES numbers after picking a charge weight

I would look very serious at that last group and see if it’s repeatable. I like .3 increments but .2 might work better. I’m not a fan of the .1. Ideally, you’d have a decent node of several tenths and it not matter where you load it.

I do like using a chrony first without shooting for groups. Look for the nodes first.

 

[ndayton]

I would look very serious at that last group and see if it’s repeatable. I like .3 increments but .2 might work better. I’m not a fan of the .1. Ideally, you’d have a decent node of several tenths and it not matter where you load it.

I do like using a chrony first without shooting for groups. Look for the nodes first.

Sure, I think what I will do is load 3 at 41.6, 41.8, and 42.0 barring any pressure issues. I have a Caldwell chrono that's a pain in the ass but I will try and set that up to record velocity numbers.

For reference I am following (sort of) this method here.
http://www.ocwreloading.com/about.html

 

[Breddoch]

I used the OCW method last year for the first time developing a load for my 280 and have been satisfied. The way I understand this first step is that you are looking for consistency in point of impact across loads ignoring group size. The purpose is to pick the load in the middle so that your point of impact will not shift based on a faster or slower velocity that may be caused by temperature, inconsistent charges or other variables. Then adjust the seating depth to dial the group size.

Sorry if I’m stating the obvious, it’s one of my finest qualities. Based on my basic understanding I see a few options:

1. If 41.8 is repeatable, call it a day. Don’t look a gift horse in the mouth. Maybe make one more load above 41.8 to make sure poi doesn’t shift before settling on that load. Check velocity to make sure it is in line with expectations with no crazy spreads.

2. Start your seating test with a load between your low two loads. I’m usually looking for more velocity so I doubt that would be the route I would take personally.

3. Take 41.2 as your spot between 41.0 and 41.4 and start your seating depth test there. I think I would want to see some velocities before settling that far below max.

I’m no expert so take it for what it’s worth but, I think I would go with some version of the first route. I will say that my most consistent loads checking for point of impact were not tightest by a stretch but I was able to tighten them with seating depth. Keep us posted.

 

[ndayton]

I used the OCW method last year for the first time developing a load for my 280 and have been satisfied. The way I understand this first step is that you are looking for consistency in point of impact across loads ignoring group size. The purpose is to pick the load in the middle so that your point of impact will not shift based on a faster or slower velocity that may be caused by temperature, inconsistent charges or other variables. Then adjust the seating depth to dial the group size.

Exactly. I just want to avoid the tiny group trap if its not repeatable or changes wildly due to environmental/ variance in reloading.

 

[Pickettpuncher]

If you haven’t checked it out, look for the satterlee method

 

[amassi]

Load all your brass at 41.8 and go shooting.
Load development done. Shoot 20 or more of them through your magnetospeed to get a velocity and get to clangin

Sent from my SM-G991U using Tapatalk

 

[Lawnboi]

You don’t have a big enough sample to tell you anything imo.

It’s a creedmoor shooting a 140. 41.5 of h4350 at factory length and hammer on.

 

[Hill Difficulty]

OP

Your method will likely leave you with gaps. (Being helpful here.)

Consider a simple approach:

1. Scrap what you're looking at/disregard groups until you're ready for groups
2. Load one each at .030" off starting at 40.5, 41, 41.5, 42, 42.5, ...
3. Shoot the loadings low to high till you notice pressure signs
4. Keep each target POI separate (don't shoot 2 bullets at the same spot) in a L to R sequence (same target you're using)
5. Don't do this without a chrono - you need velocities

The FPS numbers and visual horizontal impacts will reveal consistencies. Look/hope/pray for L to R bullet POIs that show a consistent horizontal sequence - so 2 or more bullets in a row at the same horizontal level, then impacts usually deviate up or down. Impacts in common without going vertical + speeds that don't make big jumps will show you where you need to be with powder charge, plus or minus one grain. At that point you can load 3 rounds for every +.2 weight and shoot pairs/groups in a L to R order to determine ideal charge (What is ES? Horizontal? Group size? Group consistencies between charges?). Then move to seating variations.

Figure 4 or 5 rounds to determine max charge and ballpark velocity/charge node + 8 to 12 rounds when ready to determine final charge.

Just a way to go about it. Additionally, this approach will prove out whether your 41.8 grain loading holds true or you jumped over a better place to be.