Question about OCW load development

[Kframe]

I'm working up 3 different bullets in 165gr for my .30-'06 rifle.

I've also been reading up on OCW development and I get the general idea, however I have a question about the 3 sight-in rounds.

In H4350, I'm trying a range from 56.7-58.3gr and my sight-in rounds will be 56.7, 57.1 and 57.5 grains.

So, when I fire those three sight-in rounds at the first target, do I adjust the scope so the POI is about an inch above the POA?

Or do I just fire those three, leave the scope alone and find the center of the triangular group and use that as the reference POI against which to judge the POI variance of the subsequent powder weight increment groups?

I don't know if this rifle is zero'd at 100yds right now, so should I load up another five or so rounds at about 56.7 and dial that in on paper, first?

Thanks!
-K

[Bart B.]

I think 100 yards is too close to use the OCW load development method. OCW methods are best past 300 yards.

About 1.8 grains difference with IMR4350 charge weights under 165-gr. bullets makes about a 100 fps change in muzzle velocity in the 2800 to 2900 fps range. Drop difference at 100 yards between them is about 3/16ths inch. To resolve that much difference on paper targets, each load has to shoot about half that much (3/32nds inch), at worst, 100 yards down range.

You can shoot four or five 3-shot groups at 100 yards with the same .30-06 load and their centers may well be scattered about a 1 inch area; they won't all be exactly at the same place. 3-shot groups at any range have little statistical significance, in my opinion.

I've reloaded 165's in two .30-06 factory sporting rifles and never saw any significant change in accuracy over a 2 grain spread in charge weight of several powders, including IMR4350, at ranges up to 300 yards. So, I suggest you load 10 rounds each in 1 grain increments of 56, 57 and 58 grains (pretty close to maximum, I think), then shoot them in 10-shot groups at 100 yards. Use the load you think shoots the best.

You can adjust your zero anywhere away from the point of aim. 1 to 2 inches high at 100 yards is good.

[Kframe]

Thanks for the reply, Bart.
My local range also has 200yd, so maybe I'll try that.

This is a sporting rifle, a JC Higgins Model 50.
From what I've heard they're known for accuracy, they just don't get gee-whiz comments due to their Sears heritage.

It's my first .30 cal rifle, and I hope to use it for deer this fall.

[Bart B.]

The only difference I think you'll see shooting at 200 is groups will be about 115% bigger than at 100 yards.

[Kframe]

It's January and I'm in Minnesota so I don't know when I'll get to the range - possibly this week as we may get a balmy 30°F in the next few days.
I'll certainly post back with my findings.

Next variable to explore: C.O.A.L.

[hooligan1]

Bart may be right, naw heck he's usually always right, but let's try some different powders first at 100. I have two 700 reminton 30-06's used in my testing of 165 grn sierra HPBT's, one with 22", one with 24" barrel.,,I have found in my testing that 55 grains IMR 4350 is a decent starting point, and I load three rnds at .003 off lands, then 3 at .005 off lands, then three at .010....what I have found is it's cheaper and faster to work on COAL in this manner, and when you fire a 3 rnd group that is as nice as you think you could work with, start addind powder in .3 grn increments until groups start to spread or pressure signs show..
I also have loads worked up for Nosler Btips, and it only took like 6-9 bullets to find a real decent coal and even less powder to find my loads then conventional OCW testing...

Give it a try, I got this from a thread I read that forum member Taylorce1 either wrote or replied to and I tried it and by golly it works and fast, he has saved me a ton of powder and bullets...
Now lets say you shoot a test group at 100 yds that can be covered with a dime, load ten rnds just the same as those and prove that load, if it was just a fluke, well you're not out much, and I find it's usually never a fluke.,,
Anyway H4350,rl19,imr4350 are all decent powders...just go to bullet makers manual and see what they recommend for powder weights...

Also I have only once found a load that actually shot decent with the manual's listed COAL.

[Bart B.]

Most people reloading the .30-06 (all cartridges, for that matter) choose the powder(s) that data lists producing the fastest muzzle velocity.

In the decades of the .30-06's use as a match rifle cartridge, the few dozen people winning most of the matches and setting records would choose a powder that produced the best accuracy. So did the arsenals and commercial factories making match ammo as well as military service ammo.

The 50 to 100 fps slower muzzle velocity that the most accurate ammo had was considered a good compromise. What's the real performance difference down range with bullets arriving on target 3 to 4 percent slower but 30 to 40 percent more accurate?

IMR4064 was the powder of choice for the .30-06 with bullets 150 to 180 grains by reloaders performing best with those doing well in competition. Arsenal match ammo had IMR4895 in their match ammo under 173-gr. bullets only because it metered more consistant charge weights than IMR4064 which was weighed by reloaders. 47 to 48 grains of it under 165 or 168 grain Sierra bullets was "the" load in the last decade of the century old 30 caliber cartridge's use in competition. A grain less for 173's and 180's. 190 and 200 grain match bullets did best with IMR4350.

Same load should produce excellent results with most other 165-grain bullets; worked up to, naturally.

[hooligan1]

I haven't tried 4064, but Bart you may have got my interest peaked..

[Kframe]

Another current factor in powder selection is basic availability.
My LGS has very little pistol powder, and although their rifle powder selection is better, there are some noticeable 'holes'.
There was no IMR 4350 in one-pounders the last several times I looked, they had an 8# but since I'm still working this up I don't want a large quantity laying around unused.

They did have 4064 by various marks, but I've read that that meters poorly and is temp sensitive - but for folks that use it, outstanding accuracy can be achieved.
I do shoot year-round, even in MN, and can be spotted at the range from 20°F to 100°F. I'm not ruling out 4064, but for now it wasn't my first choice.

They had a can of w760 but no H414, they had 4598 but no 748.
The only Vihtavuori in stock was a can of N130 (Nosler suggests N150 as a particularly well-suited powder for .30-06).

So, they had H4350 and I hope it works well.
My rifle is not some F-class that is even going to be able to wring out every last shred of accuracy from any round, it's a hunting rifle.
A good hunting rifle, but nevertheless one with a sporting profile barrel and a 4x scope, so although I do want to get groups as small as possible with it, in reality minute-of-whitetail is what it was built to do.

It's 22°F out right now, I just may go to the range this afternoon.

[Unclenick]

All your sighters need to do is foul the barrel and let you adjust the sights to be sure you are somewhere on paper with them all. The exact position isn't really relevant to load development. All you need is to have a consistent point of aim on your targets and be able to locate each hole afterward.

200 yards is better than 100. Creighton Audette always fired his ladders at 200 yards. Randolf Constantine later suggested 300 is better, and it is, but if you can measure carefully, you can use shorter ranges. The thing you are looking is POI change due to barrel vibration, not velocity difference. The lighter and more whippy the barrel, the more of that you get, so the exact range at which you can resolve it well enough will depend on the gun barrel's response to the load more than anything else. On the plus side, if your gun barrel whips enough to give you a read at shorter ranges than 300 yards, you'll have less wind deflection to allow for. That can confuse finding the POI.

One of the problems with three shot groups is they have a high standard error. Standard error is the standard deviation of the average value. In this case, that's the average location of the holes. The bottom line is that the group center moves around. Below is an image of a 1000 "shot" random distribution "fired" in Excel. Next to it are the first three sets of three that started off the 1000. Note the green X's, which are the centers of each group of thee and how they don't provide an exact sight adjustment because one group doesn't share the center of the next very closely. So an approximate sight setting is all you can get from 3 shots anyway, unless you have a larger non-random or else non-normally distributed influence significantly affecting the size of your groups.



The concept of Dan Newberry's OCW system is trying to locate three groups of three in a row that come closest to having the same POI. That is complicated by standard error randomly moving some centers. For that reason, I use a running average of 3 group centers in a row, and look for the running average to clump up somewhere as an indicator. That way I am actually looking at 9 shots at a time. Below is an example from data from Pond, James Pond, another board member. You can see how the centers of the 3 shot groups, the purple diamonds, move around and make the sweet spot uncertain, but the centers of the running average, the yellow circles, make it easier to distinguish when adjacent sets are close to one another. In this case, the best load is right between the two closest together yellow circles.

This target is just at 100 meters, by the way. His CZ sporter barrel had enough whip for something to be discerned at that range, despite it being short. I had him feed me data by measuring each hole location X and Y values from a common point relative to the aim point. The lower left corner of the target paper is often convenient, as the hole center X location then is just its distance from the left edge of the paper, and its Y location is just its distance from the bottom of the paper. These values can be put into Excel and plotted in an X-Y chart.

[Bart B.]

Group shooting and OCW along with all sorts of best load developemnt is something I've never done, except for the .264 Win Mag and one new bullet for the .308 Win for which no data had been developed for. I've just used what others have great success with in all sorts of barrels. All those loads shot as well in my barrels as theirs did in their barrels. My load that shot well in the .308 was a few tenths off from what was used in a half dozen match rifles developing it then shot very accurate in a few dozen rifles from around the world; it tested about 3 inches at 600 yards.

I've been convinced for decades if a load worked up in a barrel that's safe to shoot with powder that produces repeatable pressue curves (upper medium burn rate range for the cartridge but never real slow or fast ones, and extruded powder instead of ball) and a grain or so below maximum published data, it'll be very accurate across several barrels. Good examples are those commercial or arsenal match ammo loads that do so well in almost everything.

But then I've been a radical about this for years. So says the pin someone gave me a long time ago to put on my shooting stool: "Bart is a radical dude!"

That plot of 1000 shots Unclenick posted (he posts excellent diagrams to explain stuff) reminds me of a similar one that was an actual plot of 270 bullet holes shot at 600 yards for the 1965 National Match lot of 7.62 NATO M118 Match ammo. The group was about 10 inches extreme spread and had a mean shot hole radius of 1.9 inches from group center. I took it to a person then asked him to pick 3 holes for his first "imaginary" group then I would pick 3 more for my first group. We would repeat that 45 more times until all 270 holes had been picked. We each had some very tiny "groups" as well as some very large ones. He then understood why Lake City Army Ammo Plant fired 270 shots in that test group to get an excellent statistical assesment of that ammo lot's accuracy. The group is shown about 5/6ths the way down in the following link:

http://www.ar15.com/mobile/topic.html?b=3&f=16&t=512887

[Kframe]

Wow, great info! Thanks unclenick and Bart!

I did make it out to the range for a bit this afternoon.
Per Bart's suggestion, I skipped the OCW workup (for today, I do already have a sequence loaded but that will wait) and instead I brought six rounds of factory Nosler ammunition, ten rounds I loaded with a Hornady SST 165, and ten rounds I loaded with a Sierra Game King 165.

I knew my scope wasn't zeroed so that's what the six factory rounds were for.
As you can see in the photos, it was shooting waaaay low at 100yds, about 8 inches low.
So after the first 3 shots I adjusted UP 8 clicks.
The second 3 were still low, so before shooting my handloads I went up another 8 clicks.
That put me high, and I'm still a tad right, but that kept me from chewing out the bull and ruining my aiming point.

The groups aren't great, but my setup wasn't, either.
Forgot my sandbags at home, so all I had were some stacked up empty 20rd ammo boxes I scrounged out of the trashbin, and my leather gloves on top to cradle the fore end.
The scope was also a wee bit out of focus, but due to the temp I couldn't twist the eyepiece to adjust (the scope is a 4x JC Higgins that is as old as the rifle, ~1952).

Enough excuses, the 10 shot groups were under 3 inches which even if I did nothing further, is good enough for deer.
I do think I see some tighter patterns within the groups, and I think with a better rest and some scope adjustment (or a better/higher-power scope) I do think this could be a 1 MOA gun at hunting ranges.
And who knows, with a little more development I may get repeatable clover-leafing at 100yds.


Sorry about the focus, phone-cam.


Remember, the POI is not pictured, but is about 3-4 inches above shots 4,5,6.





All I know for certain is I'm sure glad I'm getting back into handloading, and I think this rifle is pretty sweet!

[Pond, James Pond]

Below is an example from data from Pond, James Pond, another board member.

Just for the record, I took Unclenick's advice recommending 40.55gr (as best as I could measure a 0.05gr increment) and when I shot that group, I pretty much got the tightest group I have ever achieved, so for me it works. (0.6MOA or something like that according to posters on that thread, IIRR)

Since then, I have done another OCW for another load and that too seems to be yielding promising results.

Next time I can measure MV for ballistic calculations.