Need opinions on first OCW test results

[Swampcrawler65]

Ok guys. Help me out here. Made it to the range today with the BMP, trying this OCW business. Here are the results. I think I see what’s going on, but I’d like to get some experienced guys looking at it. Gimme your thoughts.

Once fired Hornady cases, resized In Whidden bushing FL die with a .288 neck bushing, shoulder bumped back .002 from fired.

H4350 and Sierra 140 Match Kings seated .020 off the lands. Federal match primers.

Loads were: 40.7, 41.0, 41.3, 41.6, 41.9, 42.2, 42.5

No pressure signs at all. No primer flattening or cratering, no sticky bolt lift.

Velocity averages (3 shots)
40.7= 2652
41.0= 2682
41.3= 2693
41.6= 2697
41.9=2733
42.2=2739
42.5=2766

And targets:

 

[Xander3Zero]

I'm no expert by any means, but without even looking at the picture I knew you would have some accuracy around 41.0-41.6 because it was a velocity flat spot. I think if your not seeing any pressure signs at all yet, you could proceed up a few increments because it looks you might come into another node around 42.5-42.8.

 

[Diver160651]

How well do you normally shoot?

Could some of the group size be attributed to you?

No disrespect, but something yo need to factor in. Honestly there appears to be a bit of dispersion that looks more shooter than like a scatter node. 41 appears to have a POI shift from 40.7; I wold not use any load on either side of a POI shift. 42.2 looks to be moving higher. (but again the groups appear to have more going one) so I would kill 41 and 4.19. Other than the dropped shot that could easily be a difference in shooter load, 41.3 might be my choice to shoot a few more and fiddle with seating.. but you could go either way.

 

[Milo 2.5]

I'd load 42.3 & 42.4 and mess with seat depth, vertical stringing minimal.

 

[Diver160651]

I'd load 42.3 & 42.4 and mess with seat depth, vertical stringing minimal.

Purely going by OWC as the OP titled the post: OWC is about POI node/shifts and keeping loads that don't start pointing somewhere else if a bit hotter or colder.

Harmonics don't always show up vertically, but I have never seen as much group diversity as in the images at only 100.. So I think there is other shooter noise like in 41.3 42.2 etc.. Again, if we are talking what the OP asked about the scatter node are key in the OWC and staying away from them are what you are after.. What groups appear to be in a scatter node? If the shooter was good to go you want to say away from these opening up or scatter nodes @ 40.7 and 42.2 .. So assuming no pressure was found, 42.5 --42.6 might be worth exploring.. But nothing close to 42.2

Ladder tests often confused with OWC are about vertical as the longer distance and shows with the node + Velocity issues and or were SD in the round robin start to cause issues.

All that said, I would agree with Milo, not because of the target, but because that is were others find very good results with H4350 and 140s. The happy spot (sands your target) should be around 42.5 a tenth on either side.

 

[spife7980]

Harmonics don't always show up vertically, but I have never seen as much group diversity as in the images at only 100..

I have and I find that’s why five shot groups are so much more valuable.

I agree with milo because it looks like the group centers are finally not moving around up and down side to side, as you said, but I would encourage testing above 42.5 as well until pressure is found but see what he has. I bet by looking at it and extrapolating the next charge level that 42.5 will come back as a good bet.

 

[Swampcrawler65]

Purely going by OWC as the OP titled the post: OWC is about POI node/shifts and keeping loads that don't start pointing somewhere else if a bit hotter or colder.

Harmonics don't always show up vertically, but I have never seen as much group diversity as in the images at only 100.. So I think there is other shooter noise like in 41.3 42.2 etc.. Again, if we are talking what the OP asked about the scatter node are key in the OWC and staying away from them are what you are after.. What groups appear to be in a scatter node? If the shooter was good to go you want to say away from these opening up or scatter nodes @ 40.7 and 42.2 .. So assuming no pressure was found, 42.5 --42.6 might be worth exploring.. But nothing close to 42.2

Ladder tests often confused with OWC are about vertical as the longer distance and shows with the node + Velocity issues and or were SD in the round robin start to cause issues.

All that said, I would agree with Milo, not because of the target, but because that is were others find very good results with H4350 and 140s. The happy spot (sands your target) should be around 42.5 a tenth on either side.

Very helpful replies.

I am more than likely a (negative) part of the equation. I’ve been a shooter my whole life but this is really my first step into getting serious about precision rifle.

I’m keeping pride and ego out of it as I truely want to become a good rifle shooter and part of that journey is acknowledging that I currently kinda suck.

That said, I was shooting from a solid cement table from bags. Everything felt and looked perfect.. I don’t know if the round robin method was also part of it or if it’s purely me.

Because of that I was putting more faith in the chrono numbers.

Should I just pick a load and get out and practice and try to improve my shooting before coming back to load development or just go off of velocity data or try a different development method?

I’m really all ears here folks.

 

[Terry H]

I wouldn't shoot round robin. Erik Cortina, one of the best competition shooters in the US uses a similar 100 yard OCW test but does not shoot round robin. Just take your time and give the barrel some time to cool. Look for velocity flat spots like you have from 41.3 to 41.6 and from 41.9 to 42.2. Look for the least vertical and a consistent water line between loads. 42.2 is a great example. Not a coincidence that it's in that velocity flat spot. Here's some of my load development work for my F-T/R /308. You see the same sort of flat water line in 43.0 and 43.2. Velocity flat. SD of 6 with ES of 11 across those loads.

Couple of data strings from the Magnetospeed.







I chose 43.0 and moved onto the seating testing. Here's that. Amazing how much .003 can make!



I loaded 43.0 @ .012 off for the first match. Shot 594 25x including my first ever 200. This is 20 shots @ 300. X ring is 1.4".



Hope this helps.

 

[Milo 2.5]

My take, if your load wont hold vertical at 100, just going to get worse, you can tighten it by playing with seat depth, neck tensions etc... If more speed is desired, get after it, I'm assuming 6.5 creed?

 

[Swampcrawler65]

Yes it’s a 24” bergara BMP Creedmoor.

Ok.. so I think I’m going to try going a bit higher as well as poking around with the 41.3-41.6 range.

Next time I may load 5 rounds per charge weight, drop the round robin business and just shoot groups over the chrono.