Trying to understand more of the upper load window

H

HopeToBe

Guest
I know there exist a bunch of threads already, I guess I have read them all, but there is still one thing that might be buggering me ever so slightly, still.

My experience shooting the 6ppc (I shoot groups only) is that the length of the tune is longer (to some degree) than when increasing the amount of powder being used. I have tested this with chronograph as well and the distance between max - min fps for each node seems to shrink. Meaning I might find a tune at 3050-3120 fps, the next at 3260-3310 fps and the final at 3350-3375 fps. From a physics point of view I assume this is natural as more energy will increase the frequency of the energy wave hence wave length will decrease, and this is equivalent to the length of the tune decreasing. But still I observe that people do, and with great success, enter the upper load window - but what am I missing? Am I just too caught up in my theoretical focus? Or is it the case that sensitivity from the temperature does decrease for each step upwards to the different nodes (in some way energy related?) ?

Any help or guidance to further understanding will be greatly appreciated.
 
HopeToBe said:
I know there exist a bunch of threads already, I guess I have read them all, but there is still one thing that might be buggering me ever so slightly, still.

My experience shooting the 6ppc (I shoot groups only) is that the length of the tune is longer (to some degree) than when increasing the amount of powder being used. I have tested this with chronograph as well and the distance between max - min fps for each node seems to shrink. Meaning I might find a tune at 3050-3120 fps, the next at 3260-3310 fps and the final at 3350-3375 fps. From a physics point of view I assume this is natural as more energy will increase the frequency of the energy wave hence wave length will decrease, and this is equivalent to the length of the tune decreasing. But still I observe that people do, and with great success, enter the upper load window - but what am I missing? Am I just too caught up in my theoretical focus? Or is it the case that sensitivity from the temperature does decrease for each step upwards to the different nodes (in some way energy related?) ?

Any help or guidance to further understanding will be greatly appreciated.
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I think your observations about velocity windows are valid.

I think the idea that the upper velocity window shows superior accuracy is an "wives tail" that is easily perpetuaded by those enamored with speed thinking that it will overcome wind effects.

There is one upper velocity window effect that is nearly undisputed, that is that powder is more efficiently burned and leaves less fouling and residue with higher velocities...............Don
 
hopetobe,
I've never ridden a horse,but I would imagine that every one is different,in strength,speed,smoothness,endurance and stamina.This I have come to understand about BR rifle barrels. The chrono numbers mean little in definitive evaluation of what a barrel/load combo can do once the "commence fire" command is given.It is more the combination of horse and rider,or barrel and shooter that cross the finish line in front of the competition.
Don't be too hasty to come to hard conclusions on a barrel/bullet combo or two. Shoot,shoot, shoot, then shoot some more ,always with an open mind and an eye to the flags.The reason BR shooters have adjustable powder measures,adjustable seating stems, adjustable neck turners and adjustable neck bushings is so that on any given day with any given barrel or bullet/powder combo we can adjust.Not so much by proven scientific formulas but by feel,and experience. I believe that is why this hobby is so enjoyable,"ya just cut it loose and let it roll".
Hope this helps you understand what it's all about. Hope to see you at a BR match in the future.
Joel
 
Upper Widow

I have shot in the upper window for years, it just seems that is where the best agging capability is.

It has nothing to do with speed, the little advantage that an extra 100 fps gives is of no consequence if you miss a condition.

I agree with Don on the cleaniness issue. When you start pushing the pressure up, 133 burns phenominolly clean. I have always said I never use anything but Butches in a barrel, I think the main reason that I get away with this is there simply isn't much left in there to clean.

In my opinion, the only draw back to shooting in an upper window is brass life. But, since we have all pretty well perfected the full length sizing operation, that isn't really that big of an issue.

I have always thought that in reality, 133 is a tad slow for a 6PPC. That is why it really responds when you jack the pressure up past 65,000 psi..........jackie
 
I agree with several things already said and especially Don's post. I can't believe how many times I've heard guys at matches talk about the "added wind bucking ability benefit of the extra velocity" associated with upper loads. I little trip through a ballistic program shows that a large increase in velocity will only gain you about .1" to .2" better wind drift at 200 yards in the most extreme conditions. As Jackie said, that little advantage will easily be overshadowed if you missed a directional or wind speed change. Not to mention the fact that if the higher end load is more wind sensitive or less accurate, it will actually INCREASE the size of your group in the same condition change!!

And remember, every bullet has a preferred rpm window for it's ultimate gyroscopic stability in a given condition. Some bullets don't like the added rpm's associated with upper end loads and will never give good results at those speeds. They will AGG much better when the muzzle velocity is reduced.

Another thing to consider, when we fill out equipment lists and reveal our charge weights, it rarely is the charge used throughout the match if even at all. Those lists are filled out before the match begins and what the competitor ends up shooting during the match is sometimes vastly different. For example, I have noticed that at Phoenix many people say they are shooting 29.+ something grains of V133 in the lists but when you walk around and look at the thrower settings and poke a few shooters about what they are doing with their charges, many are NOT using 29 or 30 grains like they may have stated. Usually, it is more like 28.+ something or even some dip down to 27.+ something grains. They are going to use what gives them the best results as they go and aren't going to stick to what they wrote down just because it's "in the list".

The few who actually do run 29.+ or 30.+ in every barrel at every range with every lot of powder are usually forcing their equipment into something THEY want rather than what the GUN wants and these folks are usually at or near the bottom of the rankings.;)
 
Shooting The Upper Load Window

Quote "When it comes to choosing a load, I will shoot the upper window. By that I mean if my rifle shoots 29 grains of N-133 equally well as it does 30 grains. I will shoot the 30 grain load."

Tony Boyer Precision Shooting Aug 2009

Quote "For those of you who advocate light loads, life isn't so simple. When you get down on the low side with your powder charge, as far as I am concerned you're in no-mans land. You can go both ways, up or down, and it gets confusing.

He has watched disciples of low velocity nervously experiment with going up a few clicks. Then when their shots begin to scatter at higher pressures they refuse to to add more powder and begin backing off, whereas if they'd continued dropping more powder, they'ed undoubtedly have watched their groups begin to shrink.

If they're going to shoot those powder puff-loads, I'm probably going to get them at 200 yards."

Tony Boyer Precision Shooting Annual 1996
 
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About tuning
A while back Gene Beggs posted that with typical length and weight Benchrest barrels, that nodes are about 1.2 grains apart. Since I read that, when I have been testing some new bullet/seating depth, using 133, and have a really bad group, in good conditions, I have changed my charge half that amount (assuming that the paper between the holes was an indication that I was between nodes) and have been pleased with the results.

Another thing that I have started to look at is bullet hole shape. Has anyone else noticed (at 100 yards) that sometimes a very light load will print a bullet hole that seems smaller and rounder, and that in that range, differences in vertical between slightly different powder charges are minimal? I got this with some 8208 a while back, and it made me wonder if I should be looking for a powder that is consistent at lower pressures than 133. The reason that I didn't want to stay with that particular batch of 8208 is that it seemed to produce an extreme amount of fouling at those pressures, and have no advantage above that.
 
jackie schmidt said:
I have always thought that in reality, 133 is a tad slow for a 6PPC. That is why it really responds when you jack the pressure up past 65,000 psi..........jackie
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Jackie
I was at the Super Shoot the year VitaVhouri came and gave out samples of their new line of powders. I always found it interesting that they recommended N130 in the 6PPC but everybody always shot N133 . Is N130 just way too fast ?

Dick
 
N132

My experience with 130 is it is too fast for the uppermost loads in a BR application. It will swell the case head at 3300+. There is or was N132 that was loaded in NATO ammo. It has never been available to the public to my knowledge. In their loading data, it seems to fall between 130 and 133.
 
Blending 133 with 130

Jerry H said:
My experience with 130 is it is too fast for the uppermost loads in a BR application. It will swell the case head at 3300+. There is or was N132 that was loaded in NATO ammo. It has never been available to the public to my knowledge. In their loading data, it seems to fall between 130 and 133.
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Jerry,

Have you ever mixed 133 with 130. Would this in effect make 132? If you did blend the two what were the results?
 
Yes, I have blended the two- 66%133 and 33% 130. It worked well for me. It has been a long time ago but I could sustain 3400 loads with it without fighting to get it in and the short brass life of 130 alone. This is not safe simple procedure though. A 50/50 mix acts very close to the faster powder.
 
HopeToBe,

It is true that the 6PPC will shoot better aggregates overall when run at the upper end of the pressure window. In fact, every cartridge I’ve ever played with shoots better when loaded at close to the “listed maximum” pressures. I’ve never been sure exactly why this is true, but I’ve assumed that the pressure curve generated from shot-to-shot is more consistent with loads at the upper end of the spectrum. It could be a combination of reasons stated by several of the shooters that responded in this thread.

Sure…you can shoot a few “wallet groups” with the light loads in windless conditions at protected ranges or in enclosed shooting tunnels. When shooting aggregates in typical range conditions you will probably find that hotter is better.

BUT in my experience, the absolute hottest loads are not the best either. One must be careful not to get too carried away with maximum loads. For example, Lapua brass can generally handle loads that would normally exceed maximum pressure with other brands of brass. The combination of Lapua brass with modern benchrest grade rifles can be a double-edged sword. Drive the bullets too hard and one can easily be fooled by the pattern of the groups. The bullet holes will appear smaller, with a very distinct black ring around the entire circumference of the hole. This is a good indicator that the rifle is almost ready to lose its tune and burn you. The gun may shoot two or three, or sometimes a five-shot group in the zeros, but it will spit a shot two or three times further than normal. Sometimes the lost shots will wonder randomly, and sometimes with the condition.

It’s a phenomena known to make some shooters believe that they have a loose or bad scope, or a loose or bad barrel – or bad bullets, et al.

Greg Walley
Kelbly's Inc.
 
Jerry H said:
Yes, I have blended the two- 66%133 and 33% 130. It worked well for me. It has been a long time ago but I could sustain 3400 loads with it without fighting to get it in and the short brass life of 130 alone. This is not safe simple procedure though. A 50/50 mix acts very close to the faster powder.
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Just curious how you got an exact 50/50 mix? If you take a pound of this and a pound of that and mix them then take a 30 grain charge out of it, it will not contain a true 50/50 blend.
 
You could use 2 powder measures. One with each different powder.
 
Are you proposing

JohnVm said:
You could use 2 powder measures. One with each different powder.
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not mixing the powder, droppimg first one and then the other or dropping both and mixing them somehow? Do you think it makes any difference if the blend isn't mixed well?

Given what most people find with measures, I am quite sure I wouldn't want to use two to make one load and have it come out correct.
 
I do not advocate blending different powders. That it has been done and will probably be done again is tricky for the vary reason you mention. Getting and keeping a uniform mix is difficult.
 
Pete, I am not experienced in this area of mixing powders but using 2 powders does create a problem of proper blend, two measures fix the proper blend problem but as you say it could give you a variation in the total weight that would be counter productive. This is why I have not really experimented with blending powders. I have had success with 2 different lots of 133 mixed.
 
JohnVm said:
Pete, I am not experienced in this area of mixing powders but using 2 powders does create a problem of proper blend, two measures fix the proper blend problem but as you say it could give you a variation in the total weight that would be counter productive. This is why I have not really experimented with blending powders. I have had success with 2 different lots of 133 mixed.
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huhhh??

And exactly HOW does "two measures fix the proper blend problem"....?????

So in your opinion throwing a bunch of dinky-winky charges is somehow more accurate than measuring once in bulk?

Please explain your theory.

al
 
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