First OCW test, Thoughts?

[CZp-01]

Built this gun for PRS. Unfortunately,I don't have more than 100yds available to me at the moment. Other ranges are still closed in my area.

Went out with some virgin Lapua 6.5CM brass for a OCW test on Sunday. First time out with my new Impact and Stutesville barrel 26" M24 1-8 prefit, TT Diamond. This is my first time trying this method and wasn't sure what it would yield. I followed all of the instructions. I believe, I've read fire formed brass should get you better accuracy?

I used multiple targets rather than just one. Shot at the wrong target once. Made it a PIA with the Chrono. Old style Caldwell premium kit. Sold my Magnetospeed wish I still had it at that moment. I wasn't overly impressed with the results. Prob more me than anything. Top half velocity is from yesterday. Bottom is from today. Didn't see any pressure signs at 42.6.

Bottom middle are my RPR handloads.

I wondered if fire formed brass would get me better accuracy?

So, I decided to use the same brass again. See if it would make a difference. Went home processed the brass, got my measurments and loaded them back up the same and went out again today. Only used one target this time. I took my time behind the trigger and focused on the fundamentals. Think I got better results today on the target. I'm thinking that 41.7 would be a good charge weight to test a lil further?

Bottom right target is my handloads for my RPR. Decided to Chrono them to see what they would do.

This is today target

What's your thoughts? View attachment 7336230View attachment 7336231View attachment 7336234View attachment 7336235
Hope, I covered it all.

Thank you for any input or suggestions.

140gr ELDM
H4350
BTO 2.207
OAL 2.820
CCI LRP
Mag length

 

[Doom]

41.7.

 

[Sirshredalot]

I am by far no expert, ..im still asking this advice as well, but to me....42gr seem to have less vertical...everything is damn near on the same line.

Why 41.7? Tighest group? Lowest spread?

Please and thank you.
Shred

 

[CZp-01]

I am by far no expert, ..im still asking this advice as well, but to me....42gr seem to have less vertical...everything is damn near on the same line.

Why 41.7? Tighest group? Lowest spread?

Please and thank you.
Shred

@Sirshredalot sharing the link with the info to the OCW test. It will shed some light on why it looks to be the best charge weight.

You're looking for multiple groups that have a similar POI. Picking the middle charge gives you a buffer for POI with change in weather, case dimensions and charge weight.

 

[Sig Marine]

41.7.

You are correct sir. Three consecutive groups with the same relative POA/POI, middle charge weight.

 

[Dthomas3523]

@Sirshredalot sharing the link with the info to the OCW test. It will shed some light on why it looks to be the best charge weight.

You're looking for multiple groups that have a similar POI. Picking the middle charge gives you a buffer for POI with change in weather, case dimensions and charge weight.

The problem with looking at POI is that it’s only really showing you part of the story.

You need to look at your chrono data. It doesn’t matter if you have the same POI at 100yds across several charge weights if you plan on shooting any distance.

If environmentals pushes you up or down on pressure/velocity, it needs to be in a node that’s close enough that your dope will still work at distance. And the node needs to also have an acceptable ES up and down.

 

[CZp-01]

The problem with looking at POI is that it’s only really showing you part of the story.

You need to look at your chrono data. It doesn’t matter if you have the same POI at 100yds across several charge weights if you plan on shooting any distance.

If environmentals pushes you up or down on pressure/velocity, it needs to be in a node that’s close enough that your dope will still work at distance. And the node needs to also have an acceptable ES up and down.

I understand that as well. I wouldn't try to run something if the numbers were trash. Just thought I would try something different.

What do you do think of the velocity numbers I provided?
Where would start with some further testing?

 

[Dthomas3523]

If you’re confident your loading routine/methods are good enough to trust your numbers posted, 42.4 it 42.5. The only charges that were close to each other in ES were 42.3 and 42.6.

OCW group tests just show where some powder charges with the seating depth you chose exit the barrel within a similar time along the barrel harmonics. If all you’re doing is shooting groups at 100, ocw works well.

But we can control this via seating depth with pretty much any charge weight you want to use. So, at distance, the chrono is what matters. Velocity is what is going to dictate vertical dispersion at distance.

So, take the powder node that is the most consistent, load in the middle, and tune your seating depth to the rifle. OCW is tuning charge weights to bullet and barrel.

It’s very important that your loading process be capable of reproducing the numbers you posted. If you loaded all of them again tomorrow and didn’t get close to the same numbers, then your loading practices need to get better.

 

[CZp-01]

If you’re confident your loading routine/methods are good enough to trust your numbers posted, 42.4 it 42.5. The only charges that were close to each other in ES were 42.3 and 42.6.

OCW group tests just show where some powder charges with the seating depth you chose exit the barrel within a similar time along the barrel harmonics. If all you’re doing is shooting groups at 100, ocw works well.

But we can control this via seating depth with pretty much any charge weight you want to use. So, at distance, the chrono is what matters. Velocity is what is going to dictate vertical dispersion at distance.

So, take the powder node that is the most consistent, load in the middle, and tune your seating depth to the rifle. OCW is tuning charge weights to bullet and barrel.

It’s very important that your loading process be capable of reproducing the numbers you posted. If you loaded all of them again tomorrow and didn’t get close to the same numbers, then your loading practices need to get better.

Thank you for the info!