New 6.5 ocw results

[yobuck]

Thanks Dan for taking the time to come and explain your theory. I hope to stop by your place in the near future and meet you.
I think probably due to my age it will be difficult for me to totaly unlock my mind to some things.
Its fine to say dont look at the group, but what are we trying to accomplish to begin with?
Does that mean that the very good group i shot with my grandsons new Savage 308 right out of the box shouldnt be counted?
Or was i just lucky enough to win the lottery with one ticket? And ill admitt that for me luck always plays a roll.
As for the molecules in the barrel steel, 25 years ago it was believed by those in the know, that the best accuracy couldnt be achieved unless the molecules
in the barrel were all properly alligned, (im not joking). The only way to achieve that was to have a specialist freeze the barrel to some
ungodly low temperature which supposedly alligned the molecules. I sent the barrel of my 30x378 out to be done. Did i notice any difference
after it came back? Well i guess i wasent a good enough shooter to notice it. And i guess not many others were either, because im not aware of
that taking place anymore. Its been widely known for as long as i can remember that velocity and accuracy dont necessarily go hand in hand.
Pick your poisen for what you need to do. There are times when a compromise can be reached with at least satisfactory results, of coarse depending on the individual view of things.
Benchrest matches wouldnt be one of them however. But its my opinion that banging steel at long distances could be.

[DanNewberry]

Thanks Dan for taking the time to come and explain your theory. I hope to stop by your place in the near future and meet you.
I think probably due to my age it will be difficult for me to totaly unlock my mind to some things.
Its fine to say dont look at the group, but what are we trying to accomplish to begin with?
Does that mean that the very good group i shot with my grandsons new Savage 308 right out of the box shouldnt be counted?
Or was i just lucky enough to win the lottery with one ticket? And ill admitt that for me luck always plays a roll.


I understand your question. If you're truly on an OCW node, accuracy should be very good. But there will be places that are outside that node where accuracy might be good for just one session, and then it is not repeatable next time out. So you want both stability of POI (point of impact) *and* a decent group. It may not be the best group of the day, but if it's a reasonable group, sandwiched in between two other reasonable groups which are centered at the same point of impact, then that should be your choice load.

Here is a sample target from some years back which might illustrate what I'm talking about:

http://img.photobucket.com/albums/v114/green788/targets/22-250w760.jpg (http://smg.photobucket.com/user/green788/media/targets/22-250w760.jpg.html)

[doctnj]

upslide I think you missed the part where I said the ones im skipping over had a large VERTICAL spread. Meaning the poi was not poa. Some were even with poa but about a tenth of a mill to the right. Looking at the entire second 'course' test they all averaged about a tenth mil to right. Probably could have dialed over one click and they all would have basically been centered but I didn't want to change anything from beginning to end. And apparently Dan seem to note the two node areas that I am going to go back and do more research on. So there it is.

[doctnj]

Upslide or anyone else for that matter;

Here is a theory that might put a question mark next to the poi, poa deal. When you are shooting a test what is your rifle zeroed with? More than likely a load that is not an accuracy node. There fore when you zero your rifle originally, it let say hit high and right, so you dial down and left. Now you are center punching the target.


Now you go out to test some loads. You run across a group that punches a size of a dime down and left of bullseye. Oh well that cant be an accuracy node because poi doesn't equal poa right. Maybe wrong! What if that indeed is where the end of the muzzle is truly neutral and your scope was dialed to compensate for less accurate ammunition?

[DanNewberry]

It isn't about where the end of the muzzle is neutral, it's about the location of the shock wave, regardless of which way the muzzle is bent when the bullet is released. Ideally, we believe that the bullet should be released at one end or the other of the vibration cycle, where it is relatively static, about to switch directions and go the other way. Remember, you're aligning your scope with the bullet path, not with the barrel.

http://img.photobucket.com/albums/v114/green788/drawings%20etc/harmonicwhip.jpg (http://smg.photobucket.com/user/green788/media/drawings%20etc/harmonicwhip.jpg.html)

[LongRange]

dan...so we are looking for the bullet to exit when the shock wave is closest to the muzzle end of the barrel for best accuracy or when the wave is at the action?

ive read a lot of chris's stuff on this as well as yours but still dont understand when is the best exit time...ive also read that the best exit time is at the highest point of the whip.

[DanNewberry]

Chris says when the shock wave is farthest from the muzzle, which will be a time when the muzzle isn't as "excited" by that wave. It is still vibrating, of course, and even with an accurate load you can see the bullets string out in a line if they are being released when the muzzle is moving quickly from one end of the vibration pattern to the other--but that line is still going to be reasonably tight, even MOA or better. If you do see a load grouping in a diagonal line, it is an easy fix; just change the seating depth by .005" (either longer or shorter) and re-test. The slight seating depth change will alter barrel time slightly, and move the point of release on that vibration pattern (in the drawing I shared on page 3) to one end or the other. If you don't see an improvement, move the seating depth in the other direction. Checking .010" seating depth changes may also be helpful.

[cowtownup]

I've certainly enjoyed reading this thread. I've always looked at barrel vibration as a sin wave and having the bullet leave at either the top or bottom of that wave when the barrel was changing directions was the ideal and hence the node... However, thinking about it in terms of a shock wave moving from one end of the barrel to the other adds to the equation. I'm looking forward to some upcoming load development I've got in mind to try and relating it to what I've learned here..

[doctnj]

I THINK this is a good example of that diagonal pattern concept. If I hadnt of shanked that one shot that would have been a much better looking group but its still at same horizontal. I guess my poi, poa idea is getting off track due to terminology. I just thought that if I zeroed my rifle with ammo that is "unknown" as far as excitation of barrel. There is NO WAY to definitively know if poi shift might not be your TRUE zero. Upslide keeps saying poi and poa is so important and should be the same. I could see that if your sighting ammunition had zero "excitation". What do we/I do after I think ive identified the correct load and it holds together...... re zero my scope to accommodate the slight difference in poi and poa. Now then the next test on the same barrel, the poi and poa should be the same because the speed of sound through that metal of your barrel is basically a constant; and upslides comment would be TRUE. Am I way off base?
http://i1075.photobucket.com/albums/w435/doctnj/6d23c662-bc3e-4548-97cf-7c9121f04f9b.jpg

[LongRange]

Thanks Dan....I was backwards in my understanding of exit time.

[DanNewberry]

doc, just try the 42.5 grains with a seating depth change, .005" shorter, and again at .005" longer. If it's on a true accuracy node, it'll tighten up and get rid of the linear group. That said, 42.7 may be closer to the actual OCW high node. And 41.4 to 41.5 on the low node is probably where you'll end up at.

[upSLIDEdown]

I guess my poi, poa idea is getting off track due to terminology. I just thought that if I zeroed my rifle with ammo that is "unknown" as far as excitation of barrel. There is NO WAY to definitively know if poi shift might not be your TRUE zero. Upslide keeps saying poi and poa is so important and should be the same. I could see that if your sighting ammunition had zero "excitation". What do we/I do after I think ive identified the correct load and it holds together...... re zero my scope to accommodate the slight difference in poi and poa. Now then the next test on the same barrel, the poi and poa should be the same because the speed of sound through that metal of your barrel is basically a constant; and upslides comment would be TRUE. Am I way off base?

I think we had a miscommunication. What I was trying to get across is what you've just said, I just may not have been saying it the best way.

When doing an OCW, nothing is going to actually hit you poa perfectly, and that's fine. That's the way it's intended. You want a rough zero, but changing the charge so much will almost certainly walk all around that point of aim. The key is finding a string of groups (usually 3 or so), where the center of the group is the same distance and direction from the point of aim. So say 3 groups in a row, the center of all of those groups is 1" from the poa, at 1 o'clock. Whatever the middle charge weight was should be your OCW. That way if you throw a hair over, or a hair under on your powder, you'll still be hitting the same point. The group size can then be tightened up by adjusting the seating depth. Once you've got the group tightened up, then you can adjust and zero your turrets so you're zeroed and should be good to go.

[doctnj]

Again, thanks Dan, as well as every one else that has chimed in. This truly has been a good crash course in load development. Which is a good thing because I was informed yesterday that the rail for one of my competition rifles will finally be here tomorrow!!!! I get to fire form brass this weekend then start load development on it next.

I wish I would have read Dan's post before I finished loading the entire test. Oh well. I did seat an additional .009 deeper than before. It puts me at a cbto length of 2.200. I like round numbers. Before seating more shallow I want to see how the pressure feels as the bolt seemed a bit sticky in the charge range of 42.7. I am re testing 42.5 and 42.7 again as well as 42.8. On the 42.8, I want to re asses weather the bolt gets noticeably more sticky at the new seating depth and that it spreads back out at that charge so I know indeed where my upper limit is. May be an incredible waste of time but hey its already loaded.

[yobuck]

Again, thanks Dan, as well as every one else that has chimed in. This truly has been a good crash course in load development. Which is a good thing because I was informed yesterday that the rail for one of my competition rifles will finally be here tomorrow!!!! I get to fire form brass this weekend then start load development on it next.

I wish I would have read Dan's post before I finished loading the entire test. Oh well. I did seat an additional .009 deeper than before. It puts me at a cbto length of 2.200. I like round numbers. Before seating more shallow I want to see how the pressure feels as the bolt seemed a bit sticky in the charge range of 42.7. I am re testing 42.5 and 42.7 again as well as 42.8. On the 42.8, I want to re asses weather the bolt gets noticeably more sticky at the new seating depth and that it spreads back out at that charge so I know indeed where my upper limit is. May be an incredible waste of time but hey its already loaded.

So why bother to fireform brass (first)? Unless its a major change in shape from the original, as might be the case with a wildcat cartridge?
Does not Dan's theory on initial load work up (OCW), rule out the need for perfect brass?
Are we wasting time, components and barrels by thinking otherwise? Mind you im not questioning you or the theory, but my interpitation of it is that it
looks for the optimal powder charge, not necessarily the perfect load. Which might be brought about by fine tuning of whatever it takes?
I have some confusion about high node low node and missing the node. Especially when looking at a good group.
Why would someone like me would consider the low node anyway? But i think i grasp the overall concept.

[upSLIDEdown]

I think you may have been trying to quote me, not Doc, but I'm not sure.

Fireformed brass will always be beneficial in my book, because it's always going to grow a little, and that's one less variable you would take out of the equation. How much difference it would really make though, I don't know. Some of that would depend on how tight the headspace was set on each particular rifle. I set my headspace pretty dang tight on a Go Gauge, to keep from having as much brass growth, and have even thought about setting it with new brass (for factory loadings, not wildcats obviously) to all but eliminate brass growth, but I've never actually done it.

As for the high and low nodes, the high node is often on the max pressure end of the spectrum, so going with the low node would sacrifice a little velocity, but would give you better brass life, and barrel life. My Creedmoor is running on a low node at 41.8gr of H4350 at 2690-2700 fps. There are a lot of people pushing them up to and over 2800fps. My load shoots one hole in my gun, if I do my part, and so far Ive gotten at least 7-8 firings on my brass and still have tight primer pockets, so I'm good with losing a little speed. It's all a give and take.

[doctnj]

Last firing, I used a Sinclair chamber gage and actually measured the head space. I discovered I hade .036 ish more than the trim to length. So I trimed them .010 longer. This could have been a contributing factor in the increase in pressure. So this time around I took them all back to standard length. I was changing too many variables at the same time to get definable results.

As far as fire forming goes, I've heard both sides. I am on here, the hide, 65 guys, 6.5 forum. On most of them I just read. When I see multiple EXPERIENCES that over lap I start lending some value to it. I fall on the side of having brass fire formed for most consistecy. I'm sure you can work up a load with out it but I think in my meager opinion that more consistency shot to shot, load to load would come from fire formed brass that gets minimally resized.
No?

[yobuck]

Whats trim legnth got to do with headspace? If we eliminated half the neck legnth, would it change the headspace?
NO it wouldnt. The definition of headspace is, (the distance measured from the face of the bolt, to the base of the cartridge, (case) when the round is fully chambered)
Depending on case design, adjustments are made from the shoulder of the case or the belt on the case. And its also possible to use both shoulder and belt on those cases having a belt, after the case has been fired in the gun.
But the neck has no bearing on it.
Case stretch is a different issue entirly. Case design can influence it to a degree, but it will always take place. Hence the need to occaisionally trim the case
Take 5 cases that youve pre fire formed and load them. Then take 5 new cases and load them. See if the groups vary much.
And after theyve been shot, are they not then fire formed?
If were looking for a (ballpark) figure on powder charge by shooting an OCW, why not fireform at the same time?
Brass stretch is controled by the chamber to a large degree. So even a low node will cause brass stretch in a factory or loose chamber. You could also have a die made for those tollerances
Im very well aware of the affect pressure has on brass as to its life expectancy. But i also spend $4.00 a dozen for live shrimp just so i can feed them to fish.
Do i really need the pressure, and do i really need the live shrimp? Thats not what im confused about with high node low node, and maybe why i need to stick with looking at groups

[doctnj]

You are correct, I meant chamber length. But the rest of the comment stands.

[LongRange]

buck the node part of the OCW gives the shooter options on the load/pressures he is comfortable shooting...ive found shooting an OCW test normally gives me 3 groups/nodes that will shoot well...1 group at low charge..1 group about mid range and 1 group at the high end or a little above...the idea is to shoot and tune the mid range load because it will be more tolerant of environmental changes and or a few kernels of powder variations or case capacity ect...

i...like you...prefer to shoot higher pressure loads to get the best performance i can from the bullets im shooting...in the OCW tests that ive shot in the last 4-6mos in 2 rifles i found 2 loads that shot very well at the highest end of the charge weights i shot and with a small seating adjustment both loads in both rifles group very well out to a 1000yds and are still very weather tolerant...i like the OCW method for load development because its quick and easy and i also think its best way for a new re-loader to start with.

ive shot a lot of ladder tests and they are effective as long as there isnt wind to deal with and the shooter is a good enough trigger man to shoot that distance....ive also shot a lot of 3 and 5 round groups at 200-300yds which is not a bad way to find a load but is better suited for mag type cals.

i guess it all boils down for the type of shooting your doing and how accurate the load needs to be...i shoot 600 and 1000yd F-class with the same loads i shoot at the long range varmint matches and do ok but this year im going to use one rifle for the F-class and see if i can tighten things up and shoot some higher scores this year.

[yobuck]

Thanks for the input, and i really do intend trying the OCW when i try some heavier bullets my 7mms.
As for the distance, we have our own range where i can shoot at paper targets at any distance i like up to 400 yds.
So id be doing the ocw at a longer distance to start with since id end up there anyway for my final testing.
As you know it's irrelevent how good or even bad my guns shoot at 100 yds.
But how im interpeting whats being said is, group size dosent matter. Its where the group center is in relationship
to the aiming point. And that good group here missed the node.
And by the way, that chick over there in the black bikini youve been watching for an hour, well she misses the node also.
Check out the fat one over there. Does that clear up how my feeble mind works? lol.