Noob Question

1. For a 338 Win. Mag. I would start low and work up in 1 grain increments until a couple of grains below published maximum and then go up in 0.5 grain increments. You have to be aware of pressure signs as you work up and stop if excess pressure occurs.

2. Some are happy with "pie plate" accuracy at 100 yards. Though that would likely get the job done, I think it's pretty sloppy criteria and I'm not happy unless I get it at less than an inch at 100 yards.

2. With the WM (using Barnes 225gr) does tenths of grains matter or, assuming I did 'work up a load' I could make the differences in my trial loads by grains instead of tenths of grains?

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EVERY gun is different and handles different loads in different ways.
I ALWAYS make sure my rifle loads are accurate to 1/10 gn.

I have noticed a change in accuracy in as little as 1/3 gn. Was it enough to no longer hit vitals? no. I have yet to make a load that wouldnt hit vitals on an animal out of one of my rifles that was zeroed in. It was 1.5 MOA vs .5 MOA at 100 yards on paper.

I would do a couple rounds at each even grain until close to the top, then tinker with the 1/10 grain measurements until you get your desired accuracy.


Me personally, I want my hunting rifle as accurate as possible. Its completely up to you on how precise you want to be. No matter what, just be sure you stay in safe margins and check for pressure signs.

The "most accurate load" refers to the smallest group, off a bench. That may be an inch or it may be 2". A lot depends on the rifle and bullet used. And what the rifle is being used for.
A Barnes 225gr., assuming a TSX, is a hunting bullet. And yes, a tenth can matter.
That "pie plate" accuracy at 100 yards is about off hand shooting skill, not rifle accuracy. If you can hit the 9" pie plate, off hand, every time, at 100, your skill is ready. Lot easier if you know the rifle and it's ammo will consistently hit into 1 MOA or less.

Only you can decide what is "good enough" for your purposes. But, yes it is very likely that there is a specific charge weight, given a certain set of components, that your rifle will shoot considerably better than other higher or lower charge weights. In this case a couple tenths of a grain aren't going to make a noticeable difference at 200yds or less. But, 2 or 3 grains likely will. If you are going to bother with hand loading rounds for hunting, why settle for sub-par performance. May take a little more time and a little investment in more components on the front end, but you will have the confidence of knowing you have an accurate load when you stare down the scope at your intended target.

It is a bit of a balancing act between finding the "perfect load" and how much you want to spend on the components to get there. With a hunting load, you also need to be aware of the velocity range for reliable expansion for the given projectile and make sure your load is giving you that at your likely shooting distance. May not be an issue in this case though. I would say, decide how many rounds you are willing to devote to the work-up, start a little above minimum, cap out a little below maximum and divide the middle ranges evenly. I usually do five rounds per load. Keep tabs of the results and you can always go back later and refine it more if you feel the need. Good luck and let us know how it goes.

Load in .5gr increments and shoot each load at a different target. That way you can see where your accuracy nodes are. I'll use my 300 WM as an example I have an accuracy node between 75 and 76.3gr of H-1000. I then took the 1.3gr spread and divided it by 5 which roughly gave me a .3gr difference per test load. Took the most consistent of those (velocity wise) that is your Optimum Charge Weight. Once you have that you play with bullet seating depth to get the accuracy you desire. I use this method on every rifle I load for (13 rifles) and ALL of them are sub MOA for 3 shots or my target rifle is sub 1/2 MOA for 5 shots.

The above mentioned 300 WM is a sub MOA rifle @ 1000 yards no matter who pulls the trigger. My 3 family members proved that.

I do not load anything like the Wm ,
308 is tops for me.

But what powder are you using? Look at the manual(s) or online and see what spread there is. Some are a lot like almost 10 grains and some are much less.

So 1/10 of a grain is not going to matter even if your powder measure is that accurate. Yes, maybe bench rest guys it will.

That will give you an idea of how much wiggle room you have to play with.

Without knowing the powder it is impossible to determine or even guesstimate.

I believe that in most cases low to middle loads are more accurate but again it depends on the powder/bullet etc etc

I put in 225gr and got 18 loads just from Hodgdon. Different bullet.

http://www.hodgdonreloading.com/data/rifle

Should I show up at my buddy's land with 20 different 'test loads' in groups of 5 each so I run through 2 boxes of TTSXs just to get a good load? Then once I find what's best, do I then do another 50 at that load or right around it to make sure??

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I don't load that caliber but it appears it has a large range from minimum to max charges which results in a lot of components used in a traditional load development .

You should always start at minimum charge . Now how do you save money and be safe doing so when you have a large gap in charge weight from min to max ? What I do is start at minimum and load 2 rounds and repeat that in 1gr increments for the first 1/3-ish of the charge spectrum .

I start this way because I'm not expecting the lower charge range to be what I end up using but still need to know I'm not over pressure at the lower charges . The next third is in 3 round groups and may be in 1gr increments but I might drop down at that point to .5gr increments . The reason I'm now shooting 3 rounds is I might find a nice load in there and you need at least 3 rounds to justify a group all while still looking for pressure signs . The last 1/3 of the charge spectrum will be 4 or 5 shots groups moving up in .5gr increments . This is where I'm expecting to find my load I ultimately use .

I should add that this is generally for hunting loads . I'm looking for the upper charge range for terminal ballistics . Because of this the minimum charges will not have the velocities I'm looking for . If I don't find an accurate enough load in the mid to upper charge/velocity range I likely need a different powder .

This is what that typical load work up looks like



This method is safe and saves on quite a few components . In the above example I saved 14 bullets , primers and powder charges .

Sierra manual generally lists their best hunting load and best accuracy load for each bullet/caliber. Similarly, Nosler shows their accuracy loads.

Now, that's on the day they tested it and using their equipment but it's a good place to start. I've actually found success with both brands using their suggested load

Good questions...

1. What you are aiming for is bench rest accuracy NOT field accuracy when testing loads.

What you are trying to achieve is the removal of as many variables in the cartridge/gun combination that adversely affect accuracy as possible, to produce the best mechanical accuracy for your gun.

Field accuracy is affected by lots of things like atmospheric conditions, shooting angles, etc. So, if you've done your job handloading and testing to find the most accurate load for your purpose, the rest will be on your shooting technique in the field position you find yourself.

2. You can work the increments as you described. It is always best to start low and work your way up carefully, checking for pressure signs every time you fire a cartridge. I don't use the accuracy loads found in some manuals as a place to start. I always start low and work my way up.

Optimal Charge Weight Testing

Here's a terrific resource to consider on the Optimal Charge Weight Method of testing ammunition...http://optimalchargeweight.embarqspace.com/

This is a really good way to find a load that is accurate and resistant to changes in pressure caused by environmental variables. For example, testing loads in the summer in hot weather, only to be shot in very cold weather when hunting.

Hope this helps...

As the 338 Win Mag has a lot of recoil while the bullets are going through the barrel, it's line of sight (and the line of fire, too) will move quite a bit in different directions for each shot after the bullet leaves the case and goes through the barrel. We don't hold a rifle against us exactly the same way for every shot. Which means our own non-repeatability in pointing the barrel at the same place every time the bullet leaves has an influence where the bullet goes. Several 3- or 5-shot groups can easily have a 3X to 4X spread in their size. If you think a 3- or 5-shot group is good enough, shoot several of them; if they're all within 10% of the same size, then 3-shot groups are good enough.

I wouldn't load charge increments any smaller that one grain apart. As most centerfire cartridges have a grain or two spread in charge weights that produce only a small change in accuracy, pick one near maximum and go with it. You will have to shoot at least 30-shot groups to get statistically significant results verifying a 10% or less change in accuracy for a given load. With the recoil a .338 Win Mag has, that'll not be easy to do.

All rifles and their ammo shoot groups somewhere between zero and a dimension; linear or angular. The smaller the largest group is for a given load, the smaller its smallest ones will be. A load that produces between .5 inch and 1.3 inch groups will typically be more accurate than one shooting .2 inch and 1.6 inch.

I see that the OCW method is mentioned. In my opinion, it is a really bad way to find a load that is accurate and resistant to changes in pressure caused by environmental variables. For example, testing loads in the summer in hot weather, only to be shot in very cold weather when hunting. Hot power shoots bullets faster than cold powder because its peak pressure is higher; all other things being equal. It's also been disproved with clamp on front sight barrel bands on the muzzle squeezing down the bore and groove diameters a bit but no change in accuracy. Match grand Garands with their bore and groove diameters growing .001" at the muzzle from cleaning rod wear show no change in accuracy; that's a greater change in diameters at the muzzle that the shock wave creates..

I agree with Bart about how many rounds are needed per group to really know how well a charge does . How ever the OP is not looking to shoot 30rnds per charge weight . My point was to try to show how to be safe while still saving some money and finding a reasonable way to get some accuracy .

As for the OCW method , to this day it still goes over my head . I mean I get the idea but every time I read it or watch people on forums explain there groups and what is best , I don't see it . Obviously it's me that has the issue but still ???

Please don't try to explain I'm not going to get it . I tried it a couple times just to see if it finds the same charge I'm using on a load I consistently shoot sub moa with , It never has . It could be because I did not go through the whole litany of COAL tests once I found a charge that was close . Mostly because It starts costing more in components then the load development I use above .

Then there's the idea of COAL and chasing the lead/throat erosion . I have a 308 that eroded .065 in 2500rds . If COAL is so important then that must mean you need to chase that lead . How ever buy doing so you are changing the internal volume of the cartridge which again takes another adjustment . Maybe the OCW method gives you enough wiggle room in pressure that all that is not an issue . Don't know , I never gave it my full concentrated effort .

OCW challenge......

If there really is a shock wave moving back and forth in the barrel that causes the bore diameter to enlarge at its location, why aren't there several evenly spaced spikes in strain gauge psi curves?

Won't the breech end of the barrel expand when that wave is at the back end where the gauge is?

If those spikes aren't in the curve, the barrel doesn't expand enough at the shock wave point to be measured.

Bart B. if the OCW method is good enough for the best long range shooters I know and for Darrell Buell who I have met and talked to on more than a few occasions its good enough for me.

OP in case you don't know who Darell Buell is he used to work at Applied Ballistics he is a long range shooting instructor and is the Captain of the US FT/R rifle team...he uses the OCW method and teaches it in his classes. Take that for what it's worth.

Which means our own non-repeatability in pointing the barrel at the same place every time the bullet leaves has an influence where the bullet goes. Several 3- or 5-shot groups can easily have a 3X to 4X spread in their size. If you think a 3- or 5-shot group is good enough, shoot several of them; if they're all within 10% of the same size, then 3-shot groups are good enough.

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I feel I should clarify and or add something to my above post on load development and how many rounds should be shot per group . When I said I shoot 3rds at mid charges and 5 at the higher charges . I should have been more clear in stating that those are initial test to see what's going to be safe and "likely" group well in my rifle . Once those test are done the results almost always gives me a group/charge that is going to be what I'm looking for . At that point I don't just call it gtg and start cranking them out .

I then load 20 each of that best group/groups and shot two separate 10 shot groups to confirm that load is indeed the right load . Now If that above load development in the above picture was for a hunting load . I'd have no problem taking those 14 bullets I saved and loading those as my confirmation loads . I'd shoot two 7 shot groups and if they grouped to my expectations . I'd have no problem calling that load good after only confirming with those 14rds . That would be a total of 50rds to find my hunting load .

In all actuality what you want in a hunting load is the terminal ballistics to achieve your goal and for your cold bore shoot to have the same POI as your POA .

I'd also like to add a question to the OCW folks . It's my understanding that what your looking for in the OCW tests is vertical stringing , is that correct ?? I believe it is and that leads me to my next point . You are not likely going to see any significant differences in you vertical string unless you are testing at 300+ yards . Would that be a fare statement ??

I bring it up for the OP to consider and if his testing will be done at 100yds or the shots he takes hunting will all be inside 300yds . Is the OCW method still the best way to find your load ??

In OCW you are looking for a "node" which is a spread of powder charges that have the same POI vertically. Vertical stringing indicate the rifle wants more or less powder. Horizontal stringing indicates the powder charge is correct but it needs seating depth adjustment. A 100yd distance for load development is perfectly fine, because you'll be using a chronograph and that will tell you the most consistent powder charge. You are looking for the lowest velocity spread.

If you're OCWing and looking for a spread of powder charges that have the same POI in the vertical plane, how accurate does each charge weight have to be to get meaningful data?

For example, a 5/10ths grain change in charge weight for a cartridge may produce a 40 fps difference in average muzzle velocity. The drop difference at 100 yards will be only 1/12th inch for a bullet leaving about 2600 fps.

OCW is nothing more than another way to bracket then divide charge weights to find out what amount gets best accuracy. They all work the same way. No test has ever been conducted that proves that "shock wave" is not at the muzzle when accuracy's the best. Other than different increments and round counts per charge weight, they're all the same. What's happening in reality is the load's tuned to be at the right place on the barrel's upswing so those leaving at a slower speed will depart at a slightly higher/greater angle above the LOS than faster ones that leave at a lower angle. It's called "positive compensation" and that's why some people put tuner weights on the barrel's muzzle end to change its resonant frequency and harmonics thereof. The Brits proved that over a century ago with their .303 rifles.

The shock wave issue is what I challenge. That wave's not big enough to show up on strain gauge measurements of chamber pressure when it's at the back end of a 30-06 barrel where it expands about .0007" at its 1.14" diameter stretching the strain gauge glued on the barrel about .0023". There's about 1/6th the peak pressure at the muzzle compared to what's at the chamber end of the barrel. Whatever bore expansion at the muzzle upon bullet exit will be much smaller (about 3/10ths as much) than what's at the chamber end for peak pressure.

I've never seen a "scatter node" over a 3 grain spread of powder in .308 Win cases through 300 yards. With 1/3 or 1/2 or full grain increments, accuracy change was not statistically significant.

Can someone explain the mechanics that proves horizontal stringing indicates the powder charge is correct but it needs bullet seating depth adjustment? As bullet seating depth changes peak and average pressure during barrel time and therefore muzzle velocity, what prevents it from changing LOF in the vertical plane and the LOF would only change in the horizontal plane? Never heard of this concept.

EDIT : I see Bart posted while I was writing the now second part to this thread . I'll comment on his post up here at the top .

Can someone explain the mechanics that proves horizontal stringing indicates the powder charge is correct but it needs bullet seating depth adjustment? As bullet seating depth changes peak and average pressure during barrel time and therefore muzzle velocity, what prevents it from changing LOF in the vertical plane and the LOF would only change in the horizontal plane? Never heard of this concept.

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I have found after a few thousand rounds through the same rifle and keeping the load data for about 80% of those shots . I have found that the consistency of the muzzle velocity in which the bullet leaves the barrel seems to have a greater effect on accuracy as a whole then anything else . It does not seem to matter what bullet 175gr smk or 178gr A-max or powder either really . Going back and looking at all my data seems to show as long as my bullet leaves at about 2560fps that load will be very accurate . Seating depth and throat erosion don't seem to effect that rifle but muzzle velocity does . That to me seems to indicate that at least for this one rifle I have the most data on . That barrel harmonics and barrel whip have more to do with accuracy . My bullet seems to need to have a very specific dwell time in the barrel .

Begin second part of this post .

Carjunkie : to your last post

See now this is where my confusion comes in about OCW . It would seem to me a traditional load development that has a little group and low ES/SD would do the same thing .

Can't you just look at all your chono data from a traditional load development and see that same node in the numbers . There should be a couple charges that the chrono will show have low ES/SD . Why not just use those as your OCW and start working on COAL if needed .

The only thing I see that's different is the round robin type order in which you shoot . Is that the ultimate difference ? Each shot is from a cold bore so it would seem that would in deed help benefit a hunting load development more then someone looking for a competition load . At the same time the round robin may have the opposite effect/result for someone loading for a competition that shoots multiple shots in a string heating the barrel quite a bit . In that case would it be better to shoot one continuous group so the barrel heats up the same as it would in your competition while you test each load/charge ?

The other issue I see and Bart has brought it up many times is how you hold the rifle effects the muzzle velocity . I did not think much of it until I did a test of my own a couple years ago .

The test was very limited but straight forward . what I did was take 10 rounds of my best 308 load I use and shoot two 5 shot strings through a chrono . One with a VERY tight grip pulled in hard to the shoulder . The other was barely touching the rifle and pretty much just letting it freely recoil . Note that the rifle was 13lbs with muzzle break so pretty easy to control . I would also suspect that the heavier the rifle gets the less you will notice this effect .

I'll add that these loads where all loaded at the same time with all the same lot components . They where stored and handled in the exact same manner from reloading bench to chamber . I loaded one shot at a time by hand . I timed the intervals of each shot of the first string ( about 45sec per shot ) and did my best to duplicate that timing in the second string . Both strings where started with a well fouled cold bore first shot . The strings were shot about 20 min apart so conditions were the same as could be .

RESULTS :

Rifle held tight to the shoulder

FPS
2517
2582
2568
2552
2568
ES=65.52 SD=28.60

Almost no pressure on rifle ,with free recoil

fps
2551
2555
2559
2552
2565
ES=14.5 SD=5.74

As said a limited test but I feel very revealing . These were all the same load . Loaded and handled in the same way . Shot on the same day in virtually identical conditions . Only difference was how the rifle was held .

Sorry to the OP . For a new reloader some of this can be a bit over whelming .

One other thing about shooting groups, or only one shot, for that matter.

When the firing pin smacks the round's primer, the bore axis is not pointing to a place above the point of aim equal to sight height above bore plus bullet drop at target range. It points somwhere else. Which direction and how much is determined on how the rifle's held and its recoil during barrel time. Only when the bore axis is finally aligned as mentioned above about 1.23 milliseconds after the round fires does the barrel point there.

Because we don't hold the rifle exactly the same from shot to shot, our own holding inconsistencies subtract from the accuracy the rifle and ammo has if fired in free recoil untouched by humans. Like bench rest folks do getting their tiny groups.

Good news is, our rifles and ammo are typically more accurate that we can shoot them.

Bad news: one shot rarely represents the center of a group of several will be. It has about the same odds of representing where the outside edge of the group is. Could be the top, right or their opposites of the group.

OP I'll tell you this if you use the OCW method I have prescribed and you do not get consistent sub-moa groups PM me the receipts for all the components you wasted and I will pay pal you the $ you are out...that is how confident I am in this method because I have seen it time and time again.

If you are only wanting to shoot groups at 100 yards then any traditional load development method works, to get consistent results from 100 yards to as far as you can shoot using the OCW method is the way to go....I have seen a guys sub MOA load at 100 yards spread to almost 4 inches at 300 yards. The reason was he had a velocity spread of almost 75 fps. He measured powder to .1gr and kept bullet seating depth +/- .003. I don't know all the sciences about it, but I KNOW that it works.

Bart B. you say that a .5gr powder charge variation doesn't matter...I respectfully disagree now at 100 yards it doesn't make a measureable difference granted but as the distance grows. A hunting load that I have for my 7mm-08 I'll use it for example a 140gr Nosler Ballistic Tip has a velocity of 2775fps and at 300yards it drops 12.88 inches, take and add the 40fps difference you state for a .5gr difference and it changes to 13.38 and 12.47 inches. Thats roughly a 1/2 inch not significant when it comes to hunting but for competition target shooting it could be a difference in an X or a miss.

And weather, humidity, barometric pressure, elevation, all can change POI as distances increase, also can "heat up or cool down" your ammo which as you stated changes pressure curve which changes the point at which the bullet leaves during the barrels "whip" I agree. The point of OCW is to get a larger window at which a rifles shoots to the same point to minimize the effects of uncontrollable variables like I already mentioned.