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Discussion Starter #1
Well, an interesting day at the range today. The test was to see if I could get 2800fps out of my SPS .308 using a 168g Nosler Ballistic Tip. I started with 44.5 grains of Varget and worked up a half grain each group gaining about 50fps each time I went up a half grain in powder. My final loads were 46grains of Varget with an OAL of 2.84 and I achieved 2840fps without any signs of pressure on the spent cases. The upper left target in the picture is 44.5g. The upper right is 45g. The lower left is 46g and the lower right is 45.5g of powder. One thing I did not do was separate the cases by weight (I'm using winchester brass and winchester large rifle primers). I say this because I noticed rather large variations in velocity and they coincided with what looks like fliers on the lower two groups. When I got back to my shed and weighed the spent cases I had as much as 7 grains difference in some of the case weights. Next trip I will separate my cases by weight and we'll see if I can't make a 1 hole 5 shot group at 100 yards (I totally believe this is possible with this gun/load combination). For reference the orange dots are 3/4". Looks like it's going to be an excellent hunting load!



 

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Discussion Starter #2
I'm betting the same thing cvc! I'll post an update when I get some time to do the reload and range work.
 

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You're most likely getting pressure readings of > 50,000 PSI. I'd seperate your brass by brand as weight differences exists.
 

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QuickLOAD suggests that Reloader 17 or IMR4895 could give a 24" barrel another 60-80 fps more velocity at the same pressure with that bullet and its seating depth, if velocity is your main objective.

Winchester cases vary all over the map. The last batch I got ran a span of about 6 grains, from 153 to 159 grains. What I did was take a piece of paper and a ruler and put the range of weights down in .1 grain intervals, then weighed and lined each case up above its weight. The most extreme weights were just a few in number, so I eliminated them. The rest resulted in what you see in the representation below. The peaks clearly show the mixed tooling the cases came off of. I would segregate your cases by tool for accuracy testing, and pull them from the column centered over one weight if that provides enough cases? The next sort should be by neck runout, favoring the lowest runout. I just did a bunch of .30-06 LC 72 brass for my dad by neck runout. The photo shows how that spread panned out. Winchester is not as tight as Lake City in this regard.

The other thing you may want to look at is Dan Newberry's site for picking best accuracy. Once you have established a best accuracy load with your Varget, provide the barrel length and your velocity data and your fired case water capacity. That gives enough data for QuickLOAD to find loads of the other powders with near same barrel time which should tend to hit the same accuracy sweet spots.



Below is brass organized by thousandths of total indicated runout in the necks (difference between thickest and thinnest part of neck).



 

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Discussion Starter #5
"if velocity is your main objective."

Well, Velocity is important but the round also has to be accurate as it's a hunting load. I've already worked up some loads with Winchester 748 and found that particular powder burns too fast for the 24" barrel to reach it's potential. I appreciate the suggestions. I'm happy with the velocity/energy that I'm getting out of this combo. Now I'd like to squeeze out some accuracy. I think being picky on the cases that I load will improve accuracy. One way or another I intend to find out!....LOL!
 

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Discussion Starter #6
You're most likely getting pressure readings of > 50,000 PSI. I'd seperate your brass by brand as weight differences exists.
I'm sure the pressure is at or greater than 50,000 PSI. The SAAMI spec for .308 max pressure is 62,000 PSI so no worries there. As far as brass goes weight differences exist even within the same brand. It is those differences I intend to eliminate before my next session.
 

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For a "hunting handload", all of the above seems like a bit much to go through. I'm not saying it isn't fun, and I have definitely gone through these steps before, but that was when I was trying to shoot target bullets into tiny little groups. For hunting loads, the results from your first post are sufficient, unless you're planning to shoot game at 300 yards, or more.
 

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Discussion Starter #8
For a "hunting handload", all of the above seems like a bit much to go through. I'm not saying it isn't fun, and I have definitely gone through these steps before, but that was when I was trying to shoot target bullets into tiny little groups. For hunting loads, the results from your first post are sufficient, unless you're planning to shoot game at 300 yards, or more.
There is the possibility of shots of 350-400 yards in colorado and new mexico. For deer sized game I wouldn't shoot that far. For Elk sized game I would if I had a load I knew would shoot tight groups and have the energy at that distance to get the job done. This particular gun, in an elk hunt, would be my backup weapon. My primary weapon is a M70 Utlra in .300WSM. I shoot 180g nosler accubonds out of it @3150fps. It will shoot .5 moa with that load. I would easily take a 400 yard shot at an elk (this past year I took a 461 yard shot) with that gun. The truth is, at that distance even shooting an elk is difficult. So many factors affect bullet flight that any number of things could go wrong. It just so happens that I connected right where by ballistics chart said I should. Result was one dead elk. I don't know if I'd have taken that shot if I didn't have absolute confidence that I could place the bullet accurately at that range. I wouldn't have had confidence if I didn't take the time in loading the bullets and testing them at the range. I guess it just makes me feel better in the field if I get everything I can out of the loads I'm shooting.
 

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700sage,

Since your post opened with your decision to get to 2800 fps, I assumed velocity was the objective. For some reason I left the last two sentences of my previous post incomplete, but have now finished them.

If you have read through the Newberry site, his method of identifying sweet spot loads is pretty efficient, but I most like his concept of finding a load that spans the widest load range without losing accuracy, as that will be most immune to temperature changes you may experience in the field. Incidentally, his recipe load for Varget with 168 grain bullets (probably developed with the Sierra MatchKing of that weight) is 46.0 grains plus a CCI 200, BR-2, or Federal 210 primer. He recommends starting at least 5% below that and working up. I just find it interesting and validating that you and he arrived at the same place by your approaches. The only difference is likely that he's using 2.800" COL.

Newberry does not sort cases, but I obviously do. I also recommend checking cartridge runout, which he does not. In some guns and loads I find it matters a lot and in some it doesn't. The looser the chamber and longer the freebore, the more it matters, IME. I always use Redding Competition bullet seaters because of this. It's the same reason I sort by neck runout (bad runout misaligns the bullet, too).

By the way, Newberry's round robin approach can also be used to identify what seating depth your gun likes best with a particular bullet. Find a low load or a squib load that works well, then substitute seating depth adjustments for powder charge adjustments. I do this with a light load because seating depth affects pressure. Once you have the seating depth optimized, then adjust powder to peak accuracy.
 

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By the way, Newberry's round robin approach can also be used to identify what seating depth your gun likes best with a particular bullet. Find a low load or a squib load that works well, then substitute seating depth adjustments for powder charge adjustments. I do this with a light load because seating depth affects pressure. Once you have the seating depth optimized, then adjust powder to peak accuracy.
Are you saying that you can find the most accurate seating depth, irrespective of powder charge, and then increase the powder used to further improve accuracy? I find that idea intriguing and have wondered for a few years now, if it is possible to load that way. I think you may have just given me a winter project. :)
 

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Discussion Starter #11
Here's how I arrived at my seating depth (which is probably not the most accurate but gives me the most case capacity).

I used an empty resized case and seated the bullet at 2.95 (I knew this wouldn't fit but used it as a starting point). I went through the process of seating the bullet deeper if my smoked bullet showed land marks. I ended up with 2.87. Then I tried to put the bullet into the magazine. I found that 2.87 wouldn't fit and had to back it down to 2.84.

This gave me the most powder capacity for that bullet in my gun. Then I usually just work the powder charge up until I find the hottest group that the gun likes. Doing this I have been able to get all of my hunting loads to shoot .75moa or less. Most end up around .5moa.


It is interesting that Newberry and myself have arrived at similar places. Being that I showed no signs of pressure I wonder what will happen if I go to 46.5g Varget? In my past experience, when you find a hot round that shoots good going up a half grain usually blows the group apart. Not always but usually. I'll have to try it and report back....nothing better than having an excuse to go to the range!
 

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700Sage,

The 45.5gr load looks promising But there are too many variables too really know for sure. Was that test a test of you, or your ammo? What did you use as a rifle rest? Was the rifle in the same position every time? Really, I'm not trying to rain on your parade and I hope that group is repeatable. I always had one problem I never could get over. That was to look at the target between shots. I couldn't handle the pressure. I'd put four into one hole and pull or jerk the fifth shot out. I found that the only way I could prevent it, was to not look at a group until all five shots had been fired. I've have one target that has nine holes in a ragged one group and the tenth hole is about 1/2" out. After the eighth hole I looked at the target. The ninth hole is the one that's out. I put the tenth shot right back in the group. The scope was a 6x Weaver. This was back before Weaver had to reorganize and their scopes were still worth the price tag. Let us know what the results are once you get every thing in line.
 

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Discussion Starter #15
700Sage,

The 45.5gr load looks promising But there are too many variables too really know for sure. Was that test a test of you, or your ammo? What did you use as a rifle rest? Was the rifle in the same position every time? Really, I'm not trying to rain on your parade and I hope that group is repeatable. I always had one problem I never could get over. That was to look at the target between shots. I couldn't handle the pressure. I'd put four into one hole and pull or jerk the fifth shot out. I found that the only way I could prevent it, was to not look at a group until all five shots had been fired. I've have one target that has nine holes in a ragged one group and the tenth hole is about 1/2" out. After the eighth hole I looked at the target. The ninth hole is the one that's out. I put the tenth shot right back in the group. The scope was a 6x Weaver. This was back before Weaver had to reorganize and their scopes were still worth the price tag. Let us know what the results are once you get every thing in line.
I used a Lead Sled II with about 80lbs of lead in the tray for a rest. The rifle was absolutely locked rock solid on every shot. What I noticed was that the fliers would either have a massive jump in velocity or a massive loss in velocity (one nice thing about shooting over the chronograph). When I say massive I'm talking about a 25-35fps jump from the average. For example the group on the lower left: the flier to the extreme right of that group chronographed at 2860, the three touching @2820's, and the other flier @2847. When I found a 7 grain difference in the weight of the resized and trimmed brass I knew I had a problem. I intend to find out tomorrow morning if the brass is to blame. As far as eliminating me, I don't have anyone else to shoot the groups for me. I've been shooting groups with my 7mm rem mag at 200 yards that measure .461" center to center on a consistant basis. I'm fairly sure most of them weren't me. I can usually tell when I throw a shot before I look at the target. It'll just feel different. Anyhow, I'll post an updated report tomorrow. Wish me luck!
 

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Discussion Starter #16
I shot today to test my theory on the fliers and got some interesting results. While I did eliminate fliers the bullets shot differently. This morning was about 20 degrees colder than the other day and I lost about 100fps of velocity off of the rounds with 46grains of Varget. Using the new numbers as a reference I tested 5 rounds with 46.5grains of Varget. I gained only about 25fps of velocity and accuracy fell apart as I suspected it would. Interestingly enough the group with 46 grains of powder still shot under .75moa even with the loss in velocity. The only test I have left to do is to change the primer. The Nosler reloading manual lists 46g of Varget as the max load out of their test gun. They, however were using federal magnum primers. I have been using standard large rifle primers. Next test will be with magnum primers to try and regain my goal of 2800fps velocity even at colder temperatures.
 

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700sage,

I'm wondering if your use of the Lead Sled is contributing to your apparent MV spread sensitivity. A really solid backup to the rifle will increase how sharply and early in recoil the recoil moments start influencing muzzle position. At least one high end rifle machine rest I've seen a copy of among the Ohio State rifle team's gear uses linear ball bearings on heavy shafting stock so the actual rifle vice can freely recoil rearward to avoid that. It seems to me the 6 mm "rail" gun in Harold Vaughn's book is set up the same way.

One criticism of the lead sleds I've heard is that some heavy magnums can crack a stock on one because of that rigidity. For that reason, when I bought one I rigged it with a couple of Sorbothane pads so it would act a little more like a human shoulder. I expect a stack of medium pile carpet remnants would achieve the same thing.


Flashhole,

I've not looked for that. I wouldn't expect it. I have heard tell that the Lee Collet dies can gradually flow the brass around some, but I haven't tried to measure it. Usually, if I'm neck sizing a load it's for accuracy, so I've already eliminated high runout cases before starting. I'll have to take a set of funky cases and shoot and neck size them that way to see if any improvement can be measured over time? In fact, if I take just one bad case and my hand press to the range, maybe I can determine that in one session?


Jason,

Yeah, you've got a winter project. Take a look at the Eric Stecker write up that Walt Berger sent Tang, paying special attention to the last paragraph. Realizing that all powders are covered by those blanket ranges, you have to suppose that it's so. I first got the idea from a letter in a German site page I can't find now. I did, however, find the content copied as item 3 on this page. (Just be prepared to scroll down to eliminate the wiggle ad.)

One thing that changes with seating depth is the amount of gas that bypasses the bullet after its release and before it gets into the lands and obturates the bore. The longer and more tapered the ogive of the bullet, the further it will be from the lands in cutting off any given amount of bypass space. My current operating theory is that there is a nominal rate of gas bypass that cushions the bullet like an air hocky table, tending to center it. Too little and it doesn't center; too much (which would result from too great a pressure differential from one end of the bullet to the other), and it tips the bullet by pushing too hard on the base. How much gas bypass and what pressure difference you get from end to end depends on the bullet diameter as well as the diameter of the space around it. For that reason you sometimes find one such sweet spot up near the bullet touching the lands, but another one can occur seated deeper in the case where the larger chamber neck diameter rather than freebore diameter is letting more gas bypass and thus delays the pressure rate of rise. (That effect is observable on chamber pressure plots when you vary seating depth.)

A testable hypothesis to prove or disprove that theory is something I haven't puzzled out yet.
 

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Discussion Starter #18
unclenick,
would you still consider the lead sled a problem if I didn't see any change with my 300wsm or my 7mm RemMag? Why would it affect only .308? More than likely the temperature is what changed the velocity. The only other thing I did different was to foul the bore (on the warmer day) with moly coated bullets. The cooler day I used standard old remington core locts (which is what I normally use to foul the bore). It could also have been a combination of the two.
 

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Sure. Change any variable and velocity will alter pretty easily. Just altering a crimp a little will do that. Lower velocity will also mean a change in barrel time that might actually be more favorable.

Try the sled with a strip or two of carpet down in the butt recess and see if it makes a difference? What would cause it to make a difference in some guns and not other is the presence or absence of recoil moments for it to exaggerate the effect of. These can be caused at times by surprisingly minor things. Locking lugs that need a little lapping. Oil that's seeped into the bedding on one side. Harold Vaughn's book, Rifle Accuracy Facts has a fairly impressive array of these that he identifies, measures, and removes in the process of accurizing a .270 sporter.
 

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My last part of this experiment will happen tomorrow. I will be using my 46g of Varget load with a magnum primer. The Nosler reloading manual said that the best results for .308 were actually achieved with magnum primers. They claim that the 46g of Varget combined with a 24" barrel and a magnum primer will garner 2820fps. I don't know at what temperature they achieved this but it will be cool tomorrow morning. Probably around 40 degrees. I like working up loads in this temperature because this is what I expect when I go hunting. My last results with a large rifle primer and this load achieved 2740fps and were fairly consistant on a 60 degree day.

The whole purpose of this experiment was to see if I could improve upon my current hunting load for this gun. My current load is 50g of Winchester 748 pushing a 150g NBT at 3000fps. For the 168 to outperform the 150 it must achieve 2800fps. Otherwise you might as well hunt with the 150 because it will be flatter shooting and deliver more energy. At 2800fps the 168g bullet generates about the same ammount of energy as the 150 and holds it better at distance because of the improved BC. We'll see what happens....

On a side note, I'm also working on some 150g NBT using varget. If I can get the same 3000fps with varget as with winchester 748 I'll be at lower pressures and it'll be better for the gun. But that's another post on another day.
 
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