Load Development

[chamokaneman]

First time I've ever tried develop a load using what I think is a form of OCW and I'm a pretty novice reloader. I picked a conservative max and shot 6 groups. The groups centers zig-zagged (as in several inches) quite a bit on the first three but the last three group centers show a definite flattening, only changing .50" to .75" from group to group. These 3 groups represented one grain of powder as I did the six in .5 grain increments.

So I took that one grain of spread and made 5 groups with .2 from group to group.

Group 1 // -1.80" group center
Group 2 // -1.63" group center
Group 3 // -.625" group center
Group 4 // +2.00" group center
Group 5 // +.25" group center

The plus and minuses are above and below the horizontal line I made for my group point of aims.

I feel like I should explore seating, etc between group 1 and 2 but the vertical spread on the individual shots in group 1 was terrible but not too bad on group 2.

I'm also intrigued by the last group just because it spread on the individual shots is the best of all the groups.

The load I'm building is for a .243 I'm going antelope hunting with this September. It's RL19 under an 80 grain hornady GMX with Federal 210 (as I recall primers) and factory winchester brass. My heaviest group (group 5) has 46.7 grains which is just .2 over what the Hornady maximum call for with no signs of trouble. On the other hand the Alliant data shows 48 grains as maximum for a 80 grain sierra bullet I believe.

So I guess my question play with seating between group 1 and 2 which is 46 grains even or explore a little heavier with maybe a group 6 and 7 or just do both?

Just curious...shooting is fun...reloading is also kind of fun but I don't want to $$$ or time.

 

[JFrank]

It’s difficult to help without seeing the target & targets your speaking of.
Also it’s helpful to define your mission, ie hunting, target shooting, plinking etc.

 

[entropy]

OAL's?

Did you eliminate the human factor as much as possible?

You are measuring the wrong value; you should be measuring group size center to center. Elevation can be adjusted with the sights. Get your group size down first, then adjust elevation with the scope or sights.

You didn't mention rifle make and rate of twist. These are factors to be considered also.

 

[JFrank]

OAL's?

Did you eliminate the human factor as much as possible?

You are measuring the wrong value; you should be measuring group size center to center. Elevation can be adjusted with the sights. Get your group size down first, then adjust elevation with the scope or sights.

You didn't mention rifle make and rate of twist. These are factors to be considered also.

I would beg to differ saying that at these early stages of powder charges or course adjustment’ the only thing we are looking for is location of the center in relationship to the groups on each side from there we determine the next area to explore and fine tune with powder and other techniques such as seating depth and neck tension , primers, if we get that far prior to testing a different powder or bullet.
J

 

[entropy]

When I do load development, I shoot them bagged from the bench, compare group size, and refine from there. Once the group is as small as I can get it, then I move it where I want with the sights or scope. Then I check drop out to the range I anticipate shooting it at. Maybe I'm not doing it the 'right' way, but I've been doing it that was for 43 years and it works.

 

[JFrank]

I understand what your saying and always appreciate an experienced reloader.
J

 

[chamokaneman]

OAL's?

Did you eliminate the human factor as much as possible?

You are measuring the wrong value; you should be measuring group size center to center. Elevation can be adjusted with the sights. Get your group size down first, then adjust elevation with the scope or sights.

You didn't mention rifle make and rate of twist. These are factors to be considered also.

90's vintage Savage 110, I believe they have 1-10. The shots were 200 yards from a rest. I'm not the best shot but I tried to achieve well controlled shots. Also, I spread the shots out, i.e. one shot at dot 1, next load up at 2, 3 and so on and then started over so I spread out errors, wind, etc throughout the shot.

 

[chamokaneman]

It’s difficult to help without seeing the target & targets your speaking of.
Also it’s helpful to define your mission, ie hunting, target shooting, plinking etc.

It's marked up pretty good.

 

[chamokaneman]

It’s difficult to help without seeing the target & targets your speaking of.
Also it’s helpful to define your mission, ie hunting, target shooting, plinking etc.

These will be antelope hunting loads.

 

[chamokaneman]

OAL's?

Did you eliminate the human factor as much as possible?

You are measuring the wrong value; you should be measuring group size center to center. Elevation can be adjusted with the sights. Get your group size down first, then adjust elevation with the scope or sights.

You didn't mention rifle make and rate of twist. These are factors to be considered also.

I seated them to 2.660. It was .020 longer than the recipe as I recall but way shorter than my chamber. I arrived at that length for no other reason than the GMX bullets have the grooves in them and I wanted to seat even with the top or bottom of them. Couldn't tell you why.

 

[JFrank]

It's marked up pretty good.View attachment 931669

I’m not an expert on OCW so generally speaking.... Look at the location of the center of the first two groups, this tells me that except for the wind messin with ya the rounds are trying to hit in relatively the same location on paper, this is good so personally speaking the center of those two charges grain wise would give me flexibility as a course tune and a direction to investigate.
I use wind flags when testing and try to pick my condition and shoot faster to avoid the changes but the flags help me understand the sometimes large groups ( I know why etc.)

 

[JFrank]

Your target also shows you the classic sin wave of Barrel harmonics , your two first groups timing are exiting the barrel at a close relationship to each other. Pretty cool stuff imo

 

[entropy]

OK. Seating depth does affect accuracy, but if you seated all to 2.66, that variable is controlled. Does this depth compress the powder at all? (I am not familiar with RL powders at all) That introduces another variable. Try this next time out; Don't do load development shooting at 200 yards. I do mine at 25 yards first, then select the load that shoots tightest, load up more, zero at 25, fire at fifty, zero there, fire at 100, zero there, then 200 if I expect to shoot at that distance. I usually leave the zero at 100 yards, and note drop at 200. Shoot all five of each load at each target before moving to the next. Shoot slowly, don't let the barrel heat up. Needless to say, don't do load development on windy days. Wind flags are a good idea; thanks for reminding me South Prairie Jim. My gun club has them out, only the 200 yard shooters regularly use them. It is good, once the gun is zeroed, to shoot in wind to learn how it affects your grouping.
From the groups, it looks like you are near or on your 'sweet spot' for this bullet/powder combination with #4 and #5. Since you have no signs of high pressure, (primers, etc.) I'd load 47, 47.3, and 47.6 and see if that tightens up the groups any. If it makes them looser, (or starts to show overpressure signs) stay at 46.7, that group will kill antelope at 200 yards if you can do it.

 

[chamokaneman]

Thanks for all the feedback.

 

[Demi-human]

It is hard to tell from just this single target, but if I were to make a bunch of assumptions, I would choose the heaviest charge weight.
Not based on overall group size, but on total change in elevation of the group shots, or lack there of in this case.



Of course keeping in mind that one grain of difference is only two percent of the total charge weight, which is a very small amount to see huge accuracy changes in a 90’s vintage hunting rifle.




It looks like it is just starting to be happy. Maybe try your “6 and 7”.
And the added speed doesn’t hurt when terminal ballistics need to be considered.
But again, not much to go on in just fifteen shots.

If I can imagine I’m seeing a sine wave pattern in these groups, I would choose the load that released the bullet just before the top of the wave.
Faster bullets exiting just before the top, while slightly slower bullets exit at the top, resulting in compensation for velocity. Barrel harmonics.

When I am looking for the Optimal Charge Weight, I kind of discount Windage and look most closely at the Elevation of the group. The one with the least change, or the range of charges that have the least elevation change is what I am seeking.

And that is step one...

I say doing your load development at 200 is a good idea. The longer distance exacerbates any detail in the load, making measuring differences easier.

 

[entropy]

Well put. One would have to discount windage when testing loads at 200. The reason I do my testing at shorter range is to eliminate one more variable; however I see where barrel harmonics would be a factor to consider at longer range.

 

[JFrank]

Good stuff Gentlemen, not being an OCW guy ( I’ve only done it a few times) puts me at a bit of a disadvantage in the conversation but I’m curious as to why select a charge release just prior to the top of wave or how that relates to a slower charge.
Perhaps I’m not understanding the thought process.
@entropy

 

[AJC1]

When testing my first rounds for ocw I am looking for vertical. The last group looks the best to me because it has the least vertical dispersion. The left right dispersion is normally wind and not harmonics.

 

[JFrank]

@AJC1 Are you not concerned with the relationship to the groups on each side of the charge weight

 

[Demi-human]

( I’ve only done it a few times) puts me at a bit of a disadvantage

I'm in good company then!



In this crude sketch I have different section of the wave blocked out. 1,2,&3.(Also crude proportions.)

With a high precision loading method #1 is the most desirable. At the peak of the wave is where the barrel is moving least and very consistent ammunition will print best here.

#2 is also good. The faster shots will exit the barrel sooner when the barrel is lower, slower shots will exit higher up in the wave, compensating for the slower bullet.(We’re talking minute measurements here. Only effecting group size, not actual placement on target.)

Position #3 is undesirable. It has the most barrel movement.

@AJC1 Are you not concerned with the relationship to the groups on each side of the charge weight

I am. As it gives clues to the charge. It’s not a node if there is not a very close group on each side.

And all this is for good ammunition. Huge velocity swings won’t be on the same wave.

 

[Ruger 15151]

The purpose of OCW testing is to identify a plateau in velocity across a powder spread. Some powders have several. You will never really get a tight group by round robin shooting, but the idea is that you will eliminate rising barrels temps and fouling variables which might throw off the results of the last loads. Again, the only purpose of this test is to find a velocity plateau so that you can load +/_ .1-.2gr and still have the same velocity and point of impact.

What you are looking for are multiple loads where the center of each group has a similar POA. you aren't looking for he tightest group nor the most horizontal groups, you can get that through seating depth and primer testing. You are just looking for groups that have simialr POA regardless of the size. In addition, loads that are .5 grains apart are not going to show you the velocity plateaus because they may be only .3-.4 grain wide. You really need to start with .3 gr spread and once you find what you think is a node, load in .2 gr increments on both sides to help you identify where the middle of the plateau is.

Therefore, from your target, I would say group #1 and #2 have the closest POA. However, because the powder spread is too large, the velocity plateau might be on either side or in the middle of those.

OCW testing requires a lot of bullets, primers, and bullets to get it right if you are starting from scratch. The best way I have found is to start loading 3 rounds in .3 gr increments about 1 1/2 gr above the posted minimum and go all the way up to where you feel the safe max is. Once you shoot these loads, you will see several groups with similar POAs (high and load nodes). Choose one and shoot loads in .2 gr increments on both sides to verify where the center of that node is and you have found your load for your components and rifle.

Here is a link if you don't already have it:

http://optimalchargeweight.embarqspace.com/ocw-overview/4529824091

 

[climbnjump]

It's RL19 under an 80 grain hornady GMX with Federal 210 (as I recall primers) and factory winchester brass. My heaviest group (group 5) has 46.7 grains which is just .2 over what the Hornady maximum call for with no signs of trouble. On the other hand the Alliant data shows 48 grains as maximum for a 80 grain sierra bullet I believe.

Actually the Alliant data is for an 80 gr Speer SP, but whether it's a Speer or Sierra isn't the issue here.

You want to be careful when comparing max charge weights for two different bullet types even though they are the same weight - bullet construction makes a difference.

The GMX is a monolithic bullet and the Speer is a cup-and-core. While your loading 0.2 gr over Hornady max for the GMX is probably not going to get you into trouble, using the max load listed for the Speer with your GMX would certainly give you an over max pressure round.

 

[chamokaneman]

Actually the Alliant data is for an 80 gr Speer SP, but whether it's a Speer or Sierra isn't the issue here.

You want to be careful when comparing max charge weights for two different bullet types even though they are the same weight - bullet construction makes a difference.

The GMX is a monolithic bullet and the Speer is a cup-and-core. While your loading 0.2 gr over Hornady max for the GMX is probably not going to get you into trouble, using the max load listed for the Speer with your GMX would certainly give you an over max pressure round.

Yeah, I went with the Hornady load because it was specific to the bullet and more conservative. The monolithic vs cup and core construction is the "why" stuff I'm eager to learn. Is the monolithic bullet just more rigid so to speak and therefore the pressure spikes higher?

 

[chamokaneman]

The purpose of OCW testing is to identify a plateau in velocity across a powder spread. Some powders have several. You will never really get a tight group by round robin shooting, but the idea is that you will eliminate rising barrels temps and fouling variables which might throw off the results of the last loads. Again, the only purpose of this test is to find a velocity plateau so that you can load +/_ .1-.2gr and still have the same velocity and point of impact.

What you are looking for are multiple loads where the center of each group has a similar POA. you aren't looking for he tightest group nor the most horizontal groups, you can get that through seating depth and primer testing. You are just looking for groups that have simialr POA regardless of the size. In addition, loads that are .5 grains apart are not going to show you the velocity plateaus because they may be only .3-.4 grain wide. You really need to start with .3 gr spread and once you find what you think is a node, load in .2 gr increments on both sides to help you identify where the middle of the plateau is.

Therefore, from your target, I would say group #1 and #2 have the closest POA. However, because the powder spread is too large, the velocity plateau might be on either side or in the middle of those.

OCW testing requires a lot of bullets, primers, and bullets to get it right if you are starting from scratch. The best way I have found is to start loading 3 rounds in .3 gr increments about 1 1/2 gr above the posted minimum and go all the way up to where you feel the safe max is. Once you shoot these loads, you will see several groups with similar POAs (high and load nodes). Choose one and shoot loads in .2 gr increments on both sides to verify where the center of that node is and you have found your load for your components and rifle.

Here is a link if you don't already have it:

http://optimalchargeweight.embarqspace.com/ocw-overview/4529824091

Thanks for the link. I've seen it but I don't think I had it saved.

 

[Ruger 15151]

The load numbers in any manual are just starting numbers. Many guys load higher that max listings. However, as mentioned earlier, bullets that have the same weight do not have the same Base to Ogive measurements. So... you could be loading both to the same COL but one is seated .030 deeper in the case so you may have more pressure.

the best thing is to use the load data as starting points. Learn to be able to identify pressure signs so you know when you are getting close to max pressure in YOUR rifle, with your chamber, barrel, case, primer, and bullet. What is max for you may not be a max charge in my rifle.

understanding pressure signs is extremely important in load development.