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Old November 26, 2011, 01:15 PM   #26
Arrowhead
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I'm pretty sure that the rifle you're loading for has a 1 in 12" twist, unless Remington's website is incorrect.
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Old November 26, 2011, 03:45 PM   #27
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No I'm sure it's a 1-10 twist. It's the older one(non threaded bbl.,no security button,& it says 1-10 on the box).
Anyway I want to thank everyone for the valuable info.
And I went out today & bought Modern Reloading 2nd edition by Richard Lee.
I choose that one because of the variety of different bullets & powders.
I've learned reloading bottle neck rifle cartridges is nothing like slamming out some 44mags.
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Old November 27, 2011, 10:48 AM   #28
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Just keep in mind that .308 is a cartridge for which there is a wide range of case capacities depending on brand. The Lee data, collected from a number of sources, doesn't include particular cases, but tends to try to stay safe with the smallest capacity cases, which are usually military. Hodgdon data, on the other hand, is developed with Winchester cases, which have the most capacity. So, for example, where Lee says the maximum charge of IMR4895 with a normal shaped 150 grain bullet is 45.5 grains, Hodgdon has 47.3 grains for the Nosler Balliststic Tip in a Winchester case. If you use Remington or Lapua brass, which is inbetween, you can go to about 46.5 grains with the Nosler BT and most other 150's.

But do learn to work up from starting loads and watch for pressure signs. Your own gun will have some individual personality.
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Old November 27, 2011, 10:54 AM   #29
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I would also suggest you look at getting the little pamphlet style reloading book that lists most of the different powder,bullets, including casting data and what not for the 308. It lists Lyman's, Hodgdon, Hornady, Speer, and much more for loading data. It is a good resource.
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Old November 28, 2011, 04:49 PM   #30
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This thread has a couple of links to Dan Newberry's Optimum Charge Weight theory. Readers need to be cautious about the theory behind his idea. It's got two issues. One is, it's never been prooved. The second one is he forgot to mention the other sound pressure wave that starts at the chamber when the round fires.

He states that a pressure wave goes from the chamber to the muzzle then back to the chamber, then repeats this cycle over and over again. This is true for a barrel all by its self. But when you screw it into a receiver, that receiver adds length to the piece of steel that pressure wave travels in. In reality, the pressure wave doesn't turn around at the breech end then go back to the muzzle. It travels back to the rear of the receiver then reverses to go back to the muzzle.

Now, about that second wave. It's the one that starts at the chamber and goes backwards to the end of the receiver, turns around and goes forward all the way to the muzzle, then starts making round trips just like the one that started forward from the chamber when the round fired.

So there's two pressure waves running back and forth in the barrel. Mr. Newberry doesn't mention this. They both travel back and forth at about 19,000 feet per second; each at different places. Both of them make a couple dozen or so round trips in the barreled action while the bullet's going down the barrel. They're both going to meet going opposite directions once in a while. I wonder what happens then.

About that pressure wave that bounces back and forth in the barreled action and supposed to change the muzzle diameter when its at that part of the barrel. How much does the diameter change? Does it change enough to let powder gas to shoot out between the bore and the bullet? If so, then all one needs to do when working up a load is fire one shot and check the bore for copper wash at the muzzle. If there's no wash, then the muzzle opened up enough to let gas squirt past the bullet as its jacked wasn't touching the bore. So that load shouldn't be used; the pressure wave was at the muzzle as the bullet left. Contrary, if there was copper wash, then the load will be accurate because the bore was tighter when the bullet left. Neither one of those pressure waves was at the muzzle when it left. Anybody believe this?

Dan Newberry has an interesting theory, but he's left out a couple of critical things to make it believeable as fact to me. While the sound pressure wave may well make the bore larger anywhere it's at, it's probably much less than the normal dimensional tolerances in the best barrel's bore and groove diameters; one ten-thousandths of an inch.

Last edited by Bart B.; November 28, 2011 at 08:56 PM.
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Old November 29, 2011, 08:23 AM   #31
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Gamehog, you stated:
Quote:
Many loads I thought were "bad" at 100 were better at 200 by 1/2.
How in the dickens does a bullet at the edge of a 100-yard group know which way to turn (up, down, left, right or a combination) so it strikes closer to the 200 yard group center?

If that happens, the bullet has to know where it's at halfway down range to the 200 yard target. Never heard of such a thing.
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Old November 29, 2011, 09:49 AM   #32
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Thanks, Bart.
I also have long wondered how those sleepy bullets know how to head back towards the bullseye after they pass the hundred yard line.

There is a www that shows drawings of bullets at the end of corkscrew spirals growing smaller and smaller as they go across the graph. But there is no scale. The NRA once reported that the "air spiral" of a freshly launched bullet was about 0.10" and that would damp out in pretty short order, feet not hundreds of yards. Not much of a corkscrew.

There was a guy on the benchrest board who had one of the Oehler Accoustic Targets at 100 yards and paper at 334 yds. He said no rifle, no caliber, no load he tried had ever shot a tighter group at 334 than it did at 100. Maybe he didn't try the right load. Right.
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Old November 29, 2011, 10:26 AM   #33
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Before you convince yourself that your chamber won't accept more than 2.810, be sure you measure the chamber and ogive for each bullet you are loading. Every bullet type is different and manufacturers, especially Hornady, don't always provide the best COL data for every bullet.

I found that the Sierra Match Kings 168 and 175 grain bullets were very close and seated about the same COL no deeper than 2.810 just like your experience.

However, the Hornady 168 grain Match and A-Max bullets have a very long point and the ogive is actually further from the bullet tip with respect to the shape than the SMKs so, although my Hornady manual recommended a COL of 2.800 for the match bullet and the A-MAX just like the SMKs, these two Hornady bullets really needed to be seated at 2.815 to 2.825 in my rifle.

I just tested the seating for the Hornady Match and got the following averages at 100 yards with H4895 loaded for 2725 fps.
COL------Average grp----Best grp---# grps
2.815---------0.516-------0.255------9
2.820---------0.598-------0.316------5
2.825---------0.565-------0.405------3

For Sierra Match King 168 grains at the same load at 100 yards I got the following results over several months.
COL------Average grp----Best grp---# grps
2.795---------0.578-------0.513------6
2.800---------0.580-------0.143------18
2.805---------0.502-------0.147------38
2.810---------0.605-------0.178------19

As you can see, my rifle likes 2.805 with SMKs.

I got similar results with 168 SMKs with Reloader 15 but my rifle liked 2656 to 2662 with Reloader 15.

With 150 grain SMKs I also had some difficult times with loads until I realized that I needed to change the COL to match my rifle and these bullets.

For 150 grain Sierra Match King using H4895 at 2700 to 2725 fps I got the following results
COL------Average grp----Best grp---# grps
2.775---------0.578-------0.347------17
2.780---------0.567-------0.360------19
2.805---------0.587-------0..420------6

At 2650 fps (load reduced to balance the shock and pressure for the deeper seating)
COL------Average grp----Best grp---# grps
2.805---------0.560-------0.261-------16

I would not recommend that you try any of this until you measure your chamber for every bullet type you use. The shapes of the bullets may actually require that you seat further out than the standard COL simply because the bullet shape is more rounded and the ogive is closer to the tip.
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Old November 29, 2011, 11:05 AM   #34
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Rimfire5, I'd rather see what the largest group was for each load. Smallest ones are the worst to judge accuracy as they're the ones that happen least often. Average ones are a little better but when all few shot groups are stacked atop each other about the point of aim, the combined group size is larger than the average; especially when only 5 shots per group is fired. 5-shot groups are not very significant, nor is the average of them.

If each load was fired in 30-shot groups, we would have a much higher level of confidence of the group representing what can be counted on all the time. And could easily be done by shooting 30 shots in a row instead of six 5-shot ones.

You say:
Quote:
As you can see, my rifle likes 2.805 with SMKs.
I can't tell what's the most accurate until I see what the largest groups are.


http://fuzzylimey.net/coachtalk/groupanal.html

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Old November 29, 2011, 12:29 PM   #35
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No I said 2.81 was the maximum cartridge length that will fit in the magazine.
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Old November 29, 2011, 04:05 PM   #36
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Bart B.,

You've confused Dan Newberry with Chris Long, who is the originator of the wave theory. That's understandable as the two communicate and Newberry has encouraged Long in his pursuit of the theory and they mention one another.

I've had some personal communications with Long in which he described and sent me a picture of a .308 heay benchrest gun (I don't see a picture of it on his site) for which he turned super tight thread tolerances with enough interference to make completely installing the barrel difficult. He said that gun exhibits the behavior you describe, causing the effective length of the barrel to increase by adding reflection in the receiver to it. With common threads, though, it isn't typically an issue. Harold Vaughn illustrates, for a typical barrel installation, over a third of the load is on the first turn below the barrel shoulder. He had to resort to a special thread form that let him put four times normal torque on a barrel to stop the distal threads (furthest from the shoulder) from slipping laterally in the receiver threads, pivoting on the first turn's engagement and thereby creating a recoil moment. This finding fits well with Long's own that conventionally threaded barrels don't couple well enough to the receiver to reflect the wave efficiently and don't affect reflection significantly. He says feedback from users indicate his calculation is always within a couple of percent of identifiable sweet spots. That comports favorably with differences in the speed of sound in different barrel steels.
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Old November 29, 2011, 05:31 PM   #37
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Unclenick, what about receivers whose face has been squared up with the tenon thread axis so the barrel torques in evenly all the way around?

Seems to me that would allow that sound pressure wave to more easily go from barrel into receiver and vice versa.

I'm still waiting for someone to prove the bullet exits when that sound wave's at the back end of the barrel.

And if the pressure wave at the muzzle expands it such that accuracy degrades, why did the three 7.62 NATO Garand barrels I wore out with metal removed enough at the muzzle from cleaning that no copper wash was visible the last 1/2 to 3/4ths inch still shoot under 4 inches at 600 yards like they did when new? The bore/groove was a few ten-thousandths larger at that point compared to the diameters back from that point.

Last edited by Bart B.; November 30, 2011 at 08:11 AM.
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Old November 29, 2011, 06:45 PM   #38
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Bart B.

I doubt anyone has the $ to shoot 30 round groups when they are developing load data. Even hand loads with Sierra Match King bullets and Match primers cost about $ 0.80 a shot. You have to be kidding if you think that anyone is going to shoot 30 rounds when good statistical sampling techniques are available to determine what loads work.

Just as an example, I calculate medians and standard deviatons for each load and if you know the formula for calculating the limits for the top 5% and bottom 5% of a distribution, you can shoot a reasonable number of 5 round groups and calculate the upper and lower bounds where 90% of any sample will fall.

For example, for the data on the 2.805 H4895 load,

2.805---------0.502-------0.147------38

8 of the groups are under 0.3 inches, 11 are under 0.4 inches and 16 are under 0.5 inches. 38 groups is a very good statistical sample size.

The median is 0.521 and the standard deviation is 0.207, that means that
90% of the groups can be expected to fall between 0.448 and 0.593 inches. Granted the smallest groups are usually anomalies as is the largest group which is usually shooter error in my case. Most people that post on this forum seem to be interested in the 'bragging group size' so I included it.

To me the median and the shape of the distribution that indicates where 90%of the groups will fall makes more sense but most peopel aren't attuned to that kind of data.

I understand that you are probably somewhat skeptical about posters claiming results, but there are 733 measured groups across 63 loads that allow me to make the statement that my Savage .308 likes 168 SMKs seated at 2.805 using H4895 powder (and Reloader 15 too for that matter).
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Old November 30, 2011, 01:44 AM   #39
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43gr. of IMR 4064, 175 SMK , fed. brass GMM primers, 2650 fps jammed in lands, 1 hole at 100 yards, 46gr of. 4064, 155 gr. lapua scenars, jammed, 2880 fps samething 1 hole . Remington 700 5R 24 inch.
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Old November 30, 2011, 07:54 AM   #40
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Rimfire5, if you look at what you posted for your 733 test groups then remember this statement you made:

Quote:
I doubt anyone has the $ to shoot 30 round groups when they are developing load data. Even hand loads with Sierra Match King bullets and Match primers cost about $ 0.80 a shot.
....it looks like you can afford to do it. But then, maybe you're the only one who can. You could have shot 48 fifteen-shot or 24 thirty-shot groups.

One 30-shot group's a lot better statistically than six 5-shot ones. And if one wants to cut their costs, shooting one 15-shot group's about 3 times more meaningful than three 5-shot groups.

And shooter error is just as responsible for the smallest group as it is the largest one. Folks shoot all directions from their call, not just towards the outside edge of the group center. Maybe we should just eliminate the two largest and two smallest groups shot.....if they're anomalies and shouldn't be counted.

You need to let the benchrest record holders that:
Quote:
Granted the smallest groups are usually anomalies.
That's the best thing you've mentioned.

Last edited by Bart B.; November 30, 2011 at 08:16 AM.
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Old November 30, 2011, 03:07 PM   #41
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Unclenick has the best advice in this thread. No two guns, even the same model, are going to mirror results from the same load data. It takes some time to develop the right load for your gun. IMO, bullet seating is going to have a huge impact on your accuracy. I use 2064 and/or 4095 in my 308 loads and those are very common powders. I would start there and load groups of 3 or 4 with a difference of .5 grains between loads. DO NOT touch your scope. Put the cross hairs on the same bulls eye and find the best grouping you can. Once you have determined your load, you can dial in the scope.
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Old November 30, 2011, 03:48 PM   #42
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lockinload, you state that no two guns, even the same model, are going to mirror results from the same load data. Do you think it's possible that 40 to 50 rifles with different barrels from around the world could all shoot the same ammo inside 3 inches at 600 yards all day long?
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Old November 30, 2011, 04:24 PM   #43
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Bart, your question is way to ambiguous but in any case the answer is no. But let's look at this another way. If all Remington 700s in a 308 are the same, why doesn't the manufacturer put out suggested balistic and load data for that gun? There are good starting loads for any caliber but each gun will have it's own personality.
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Old November 30, 2011, 08:06 PM   #44
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Lock 'n Load, in response to your thinking my question is way to ambiguous and your answer is no, consider what's happened.

In early 1991, a few of us developed a load for the .308 Win. to shoot Sierra's yet to be introduced 155-gr. Palma bullet. Over half a dozen rifles were used for accuracy tests at long range. We ended up loading a couple hundred thousand rounds of new Winchester cases, Fed. 210M primers and 45.3 grains of IMR4895 metered to a 3/10ths grain spread under that bullet. One test of 20 rounds at random put all of 'em into 2.7 inches at 600 yards. A picture of that group's in a fall 1991 issue of Handloader magazine.

When that load was used in the 1991 Rocky Mountain Palma Matches (I had the top combined aggregate score over 4 days of long range matches) and the 1992 World Long Range Championships, a few dozen folks from around the world all commented it definitely held 3 inches or better at 600 yards. At 1000, it shot under 7 inches. That's with new cases and metered charges in all sorts of actions and barrels with various bore, groove and chamber dimensions.

Good lots of commercial .308 Win. match ammo are known to shoot under 4 inches at 600 yards in many 7.62 Garands and M14/M1A match rifles - semiautos whose parts are very hard to get back into battery exactly the same for each shot for best accuracy. And the military teams have often shot handloads with new cases with commercial match bullets that shot that well in all their team rifles.

It's best if you ask the arms company about them publishing load data for their products.

Last edited by Bart B.; December 1, 2011 at 08:34 AM.
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Old December 1, 2011, 08:33 AM   #45
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Bart B.

If you read what I wrote

"I doubt anyone has the $ to shoot 30 round groups when they are developing load data. Even hand loads with Sierra Match King bullets and Match primers cost about $ 0.80 a shot. "

You'll note that I said when they are developing load data.

That is what the 733 groups were used to do.
So don't presume you know why I spend my $ shooting. I'm not doing it to convince you of anything. I'm doing it to determine what to load, how deep to load into the rifling, and what weights of bullets and powders get the most out of my rifle.

I don't know what you shoot groups for but I do it to determine what my rifle shoots the best.

Rather than shoot 30, 20 or even 15 round groups, I can find out trends statistically about what my rifle prefers by shooting a statistically significant number of smaller 5 round groups. Granted some of them were shot on a number of different days under different conditions, but that is the way my rifle is used so it has more significance than shooting 30 rounds in one large group in one sitting.

I take it you don't get the significance of calculating the 90% percent range of performance aound a mean.
Knowing that the next group I shoot has a 90% chance of falling between between 0.448 and 0.593 inches has a lot more value to me in predicting that my rifle will shoot within 0.6 MOA with a particular ammunition than knowing that I shot one 30 round group that was nn inches across.

To each his own. Just don't think your approach fits all purposes.
I don't doubt your approach satisfies you and may be more correct for some use.
That doesn't mean all other approaches are worthless, only that they are different and may have value for other purposes than yours, whatever that may be.
In my case, I think my approach does exactly what I expect it to do and answers the OPs question reasonably well within my experience.
It gives him an idea of what type of results he should expect based upon other shooter's experience.
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Old December 1, 2011, 09:07 AM   #46
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Bart,

Good information and I am not looking for an argument but your example, is that of a group of apparent "match" rifles and being fired by "competitive" long range shooters. For the "average" shooter/hunter who is trying to work up a load for his/her gun there is a proven process. That said, I spent several months last year working up a load for my 308 and interestingly my load data will be very close to your aforementioned data. I will double check my grains when I get home tonight. During the process I was testing 2064, 4095 and H335. I was pretty confident that the 2064 was going to end up with the best results but in the end I am using a Winchester case, 4095, fed primers and a 165 Hornaday SST 30452. I will double check grains loaded.
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Old December 1, 2011, 11:58 AM   #47
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Rimfire, shooting at least 15 shots per group is good for all rifles, regardless of their design, cost and intended use. Ammunition never knows what it's being shot in.

US military arsenals shoot several dozen, sometimes two to three hundred shots per test group for service rifles. And they're less accurate than commercial rifles. They use mean radius as the method, which, with a couple hundred rounds, is very accurate.

Last edited by Bart B.; December 1, 2011 at 12:10 PM.
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Old December 1, 2011, 12:09 PM   #48
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It seems like everyone is overlooking the Nosler 175gr Custom Competition bullet.

I find that it outshoots the SMK of the same weight in my Rem 700 SS 5-R Milspec.

If one is looking for a real inexpensive 168 gr bullet, check out the Nosler Custom Comp 168 gr packaged in boxes of 1,000. Only .21/bullet from Powder Valley.
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Old December 3, 2011, 03:59 PM   #49
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In my LTR I have had good luck with 45.5g IMR 4064 for 150's and 42.7g IMR 4064 for 165's, both at 2.800. Every rifle is different. I use this one for hunting and gives me 3/4 groups or less at 100 yds. Good luck in your search.
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Old December 4, 2011, 09:07 AM   #50
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Ignoring the practicality issues of this debate for a moment; the Central Limit Theorem (the basis for inferential statistics - predictive statistics) says, " a sufficiently large number of samples of random samples will approximate a normal distribution..." Each sample in the set of samples should be of at least 30 data points.

However, there is a unit of analysis problem here - you all are talking about individual rounds as if they are the data points. They are not. The measurements are of group size. A single measurement. No individual bullet hole provides any information at all, it is only in its relationship to the other bullet holes fired at the same time. So, five rounds or 30 are not inherently better or worse.

However, one five-round group is just an N of 1. Firing 10 5-round (50 individual rounds) groups will give approximately the same information as will firing 10 30-round (300 individual rounds) groups. However, if you take those 300 rounds and fire them as 5-round groups, ceteris paribus, you will have a sample size of N=60 and dramatically increase the power of your prediction.

I'm just saying...
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