Testing the 155.5G Bergers

Ishodu

Ishodu

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Well I had these bullets for awhile now but never got time to play with them so I did my first test with them today at 100m. It took me a long time to shoot them all as the wind was really bugging me and my hands were freezing as well. I can't really say anything shot bad, but there looks to be a few real good places to try some more loads. Looking at my chart it says that the bullet could drift as much as .6" with the wind I was dealing with.
After laying the targets on top of each other and looking to see the vertical diff between the loads its still hard to decide as from the lowest to the highest have less than 3/8" diff I would say the least change in highth is between 45-45.6 and 46.5-46.8.
All groups in center to center from 100m

So what do you think I should do? I am trying to develop this load for shooting as far as 900m.

loads.jpg
 
Try the 'better' loads at longer range. I've had loads group what I think is half decent at 100 and fall to pieces past that. While aiming error is minimized at 100 yards, the bullet really hasn't been airborne for a long enough period that the variations or tendencies for 'flyers' becomes apparent in a good shooting rifle.

Also, groups of five will reflect a better 'average'. I've had three shots go into a nice group, then the second two group nicely in a second cluster. Another head scratcher as to why, but it happens.
 
46.8 looks good. looking at your vertical. 3rds is a little to small to get a official say tho.

What primers are you using?

If I was you i would do either an ocw or ladder test.
 
If you lay the targets on top of each other there is a ladder test to be seen. I had mentioned in the post that "After laying the targets on top of each other and looking to see the vertical diff between the loads its still hard to decide as from the lowest to the highest have less than 3/8" diff I would say the least change in highth is between 45-45.6 and 46.5-46.8."

I will do 5 shots now that I have a idea where to go so far with this rifle I have never really had seen much diff between a 3 or 5 round group for what its worth.
I am using CCI BR2 for a primer.
 
Ishodu said:
I am trying to develop this load for shooting as far as 900m.
Click to expand...

I think you need to make a couple of changes in your testing to get meaningful results.

1. Shoot at 200 meters or better still 300 meters. Vertical will be 4 times at 200 and 9 times at 300, so much easier to see and measure. Also the vertical will tend to stand out more from the inherent inaccuracy of the setup, which tends to be linear instead of exponential.

2. Calculate the average vertical POI for each group compared to the aim point, and plot the average elevation for the group vs velocity and powder weight. Ignore the horizontal. You are not looking for small group size (although that should happen too), but really flat spots where velocity and powder weight increases but elevation does not, or even dips a little. Then test around these flat spot areas to refine the load. Here is an example with three different bullets at 300 meters.

LadderVel.jpg

LadderGrains.jpg
 
The Canadian National Fullbore team selected these bullets (...and Krieger barrels) for use at the World Long Range Championships in Brisbane this year. TR shooters are pretty much the undisputed authorities on 308 precision.

They tend to use these bullets with much more jump than you are using (20-40 thou). The gun will tell you what it likes, but this may be something to keep in mind.

With 30" barrels, they typically have them running very close to 3000 fps.

I hope this helps
 
I started using these bullets last year and I am very pleased with them. They are by far the easiest, most forgiving .308 target bullet I've ever done load development on (a vast overstatement; I loaded up ammo with them, and they shot well at 900m!).

You don't say what chamber is in your rifle nor how long your barrel is (looking at the charge weights and your velocities I am guessing that it is shorter than 30"?).

Some bullets are quite tolerant of jump to lands and the Berger 155.5 in my experience and in others' too tends to be one of them. You can take advantage of this by loading with 20thou or 40 thou of jump. Depending on the tools that you have it can actually be remarkably tricky to actually measure exactly where your lands are; if you are off by a bit and if you are (you think) loading your ammo either just barely into or just barely off the lands, what can happen is that *some* of the rounds in your box might actually be into the lands and some off the lands, and this can make your shot to shot uniformity suffer. But if you load to (say) 20 thou off the lands, if you're wrong and your ammo actually varies from 17 thou to 23 thou off the lands, this is often quite benign and you can get away with it.

If you have weighed your individual charge weights I am surprised to see such large E.S. figures, especially with only three shots. It might be that loading your ammo so that it has a bit of jump (or the other most important thing to investigate is whether your case neck tension is uniform) that you can improve on that substantially. With quality components (and Varget and B155.5s are) you ought to be able to get 10-20 shots ES's of no more than 30fps, somewhere between 45 and 47 grains of Varget.

Don't worry about testing at 100 yards. Even though you have to shoot at 900m or 1000y to be sure, an awfully good starting place is to have ammo that shoots very accurately at 100y and is at least "decent" over the chronograph (10+ shot SDs of 15fps or less, or ESs of 45fps or less). In fact if you get the B155.5s shooting accurately at 100y (*average* 5-shot group size of 0.6" or better) and you get SDs of 15 or better, you are 99% likely to have something that will work really well at 1000y.
 
I'm recovering from back surgery, so I can't get out to ladder test my Berger 155.5's, so I'm following this thread with interest. What I can say is that the ogive is different enough from my current bullet (Amax 155) that I've had to seat the Bergers much less deep than I'd expected. I was going for a ten thou jump, but was unable to get that, so I'm glad to hear they like a larger jump.

While I'm at it, I must admit my ignorance: what do "SD" and "ES" mean? :redface:
 
Yes the B155.5s (and also the #2156 Sierra 155s) really are nice in that so much of their length is in the nose of the bullet. It is a nice match for rifles with short-ish throats, it puts the base of the bullet right where you'd most prefer to have it (somewhere in the case neck rather than into the main case volume). The Lapua 155 is quite a different bullet in this regard, it is a much better match to rifles with long throats (yes factory-chambered Remington .308s I'm looking at you...).

"SD" is short for Standard Deviation, "ES" for Extreme Spread, and they refer to the amount of variation in velocity in a string of shots. Extreme Spread is simply the difference in speed between the slowest shot and fastest shot in the string. Standard Deviation is a better statistical measure and takes into account from all shots but is a bit more elaborate to calculate. Interestingly with most groups it will usually be the case that the ES will be about three times as big as the SD.

Smaller numbers are better for long range shooting (800y and beyond), since slower bullets will have a longer time of flight during which they will fall more than faster bullets (shorter time of flight), and this will lead to a group "stringing" vertically.

Typical factory ammo can easily have SDs of 50 and ESs of 150 fps (meaning if you fire ten or 15 shots, you will see 150fps difference between the slowest and fastest bullet). This sort of speed variation can have surprisingly little effect in on-target accuracy out to several hundred yards. In fact the first DCRA gold medallion I ever won was at 600 yards with a .308 F Class rifle firing Lapua 155s with some really ratty muzzle velocities (ES of about 100 if I recall correctly).

For shooting at 1000 yards it is quite useful to work on achieving SDs of 15 or less (or ESs of 45 or less). Velocity variations bigger than this can easily increase your vertical spread enough to hurt your scores. Even better SDs/ESs are possible and are often achieved by very conscientious handloaders, and can help make additional small improvements to 1000y accuracy.

Ishodu thanks for the barrel length. Now I am curious about the throat length in these Savages, approximately what is your cartridge overall length, is it 2.9x" or 3.0x" ? With over 47 grains of Varget you are getting less than 3000fps so some things in your system are slightly on the "slow-ish" side (nothing wrong with that, load development will adjust), perhaps your lot of Varget is slow-ish, perhaps your throat is longer, perhaps you are using Winchester rather than Lapua brass, etc. It's almost certainly the case that somewhere between 2900fps and 3025 fps you will find a load good for all ranges including 1000 yards. The main things I would suggest are:

- try 20-40 thou jump

- try mid to high 2900s

- make sure your neck tension is uniform (sometimes more neck tension can help this, sometimes less neck tension can help)

- make sure your loaded ammo is straight. Borrow a runout gauge from a friend if you don't have one, make sure your T.I.R. (total indicated runout) is less than 10 thou (don't fuss about getting it better than 5 thou).

- after you get all of these things sorted out, if you still have SDs/ESs that look like they could be improved, you could try different primers

Most importantly, do go out and shoot with the ORA at the earliest opportunity, even 1000 yards even if your ammo isn't "fully ready".
 
rnbra-shooter said:
Yes the B155.5s (and also the #2156 Sierra 155s) really are nice in that so much of their length is in the nose of the bullet. It is a nice match for rifles with short-ish throats, it puts the base of the bullet right where you'd most prefer to have it (somewhere in the case neck rather than into the main case volume). The Lapua 155 is quite a different bullet in this regard, it is a much better match to rifles with long throats (yes factory-chambered Remington .308s I'm looking at you...).

"SD" is short for Standard Deviation, "ES" for Extreme Spread, and they refer to the amount of variation in velocity in a string of shots. Extreme Spread is simply the difference in speed between the slowest shot and fastest shot in the string. Standard Deviation is a better statistical measure and takes into account from all shots but is a bit more elaborate to calculate. Interestingly with most groups it will usually be the case that the ES will be about three times as big as the SD.

Smaller numbers are better for long range shooting (800y and beyond), since slower bullets will have a longer time of flight during which they will fall more than faster bullets (shorter time of flight), and this will lead to a group "stringing" vertically.

Typical factory ammo can easily have SDs of 50 and ESs of 150 fps (meaning if you fire ten or 15 shots, you will see 150fps difference between the slowest and fastest bullet). This sort of speed variation can have surprisingly little effect in on-target accuracy out to several hundred yards. In fact the first DCRA gold medallion I ever won was at 600 yards with a .308 F Class rifle firing Lapua 155s with some really ratty muzzle velocities (ES of about 100 if I recall correctly).

For shooting at 1000 yards it is quite useful to work on achieving SDs of 15 or less (or ESs of 45 or less). Velocity variations bigger than this can easily increase your vertical spread enough to hurt your scores. Even better SDs/ESs are possible and are often achieved by very conscientious handloaders, and can help make additional small improvements to 1000y accuracy.

Ishodu thanks for the barrel length. Now I am curious about the throat length in these Savages, approximately what is your cartridge overall length, is it 2.9x" or 3.0x" ? With over 47 grains of Varget you are getting less than 3000fps so some things in your system are slightly on the "slow-ish" side (nothing wrong with that, load development will adjust), perhaps your lot of Varget is slow-ish, perhaps your throat is longer, perhaps you are using Winchester rather than Lapua brass, etc. It's almost certainly the case that somewhere between 2900fps and 3025 fps you will find a load good for all ranges including 1000 yards. The main things I would suggest are:

- try 20-40 thou jump

- try mid to high 2900s

- make sure your neck tension is uniform (sometimes more neck tension can help this, sometimes less neck tension can help)

- make sure your loaded ammo is straight. Borrow a runout gauge from a friend if you don't have one, make sure your T.I.R. (total indicated runout) is less than 10 thou (don't fuss about getting it better than 5 thou).

- after you get all of these things sorted out, if you still have SDs/ESs that look like they could be improved, you could try different primers

Most importantly, do go out and shoot with the ORA at the earliest opportunity, even 1000 yards even if your ammo isn't "fully ready".
Click to expand...
Thanks for all the help. The throat seems to be quite short, I don't have any of the these ones loaded to check the OAL as I just normally measure off the taper with an attachment rather than the tip. But I normally use horandy 168g BTHP and I can only go a few tho over the spec before I touch the lands. What I have been doing to measure it is size a neck so its fairly snug then just start the bullet in chamber it, remove it and measure. I do this at least 5 times and most of the time its the same measurement. Then I smoke the bullet and try once more to confirm its the lands.
And I would tend to that my lot of Varget could be slow I use it in my 223 as well and can never get book velocity with it either.
As for neck tension should I just measure ID? I do have a neck turning tool as well that so far never used.
The Brass is Norma the pockets have been uniformed as well as the flash hole and deburred. And sorted by + or - 1grain.
I have a runout gauge and I measured all of it and the worst was .0025" about 1/2 way down the taper most are less than .001".

Thanks for the help.
 
Following this thread with great interest. Ishodu, thanks for doing this and thanks to the rest of you for the insight and relevant comments. I am getting ready to load up some of the same bullets and this will be extremely helpful. :D
 
In your method of finding the lands, are you closing the bolt and therefore causing the bullet to be pushed into the case? If so you are probably pushing the bullet quite deeply into the lands, as in 20 or 30 thou of engagement. If you can see _any_ marks on the bullet, you are actually in the lands quite a bit (at least ten thou if not more). If this describes your situation you might want to just try seating your bullet about 40 or 50 thou deeper than you are presently, and test that both for accuracy as well as for velocity uniformity. Pretty much any load of 46.something or 47.something really ought to do brilliantly for you.

No need to neck turn.

Measuring neck ID is quite a pain without the right tools and is a bit of hassle with the right tools ("tubing" mic). Much simpler is to just use a proven method (there are many). Are you using a sizing die that uses an expander button? If so, make a point of ensuring that the case mouths are lubricated on the inside, so that a consistent amount of friction happens from case to case. Another good way to get very uniform neck tension is to use a Lee collet die.
 
Very little tension is used I wouldn't think that it would be pushing it into the lands that much, as I pull it out with my fingers quite easy.. Also I have been using the collet die. And when I size I turn the brass a little bit and size at least 4 times this keep the neck run out very low for me.
 
Interesting comment Daniel, I have never heard anyone claim a collet die is good for consistent neck tension !:)

Neck tension is the sum of not just its re-sized diameter, but the quality of the brass as well. The problems with jam-seating (finger tight,,, seat the bullets when closing the bolt) are many... Unless you anneal brass, with worked brass you are likely to have brass with very different neck tension from piece-to-piece, so there will be a great deal of difference in the seating depth. This creates huge differences in pressure. Also, depending on the dimensions of your chamber and your throat, you may be imposing yaw on the bullets as they seat.

I personally think this method is poor.

There are many ways to measure seating depth, but investing in a tool for the purpose, and being careful, repeating the measurements to confirm etc. is really the way to go.
 
@Ishodu OK it sounds like you are doing a good job of measuring where your lands are. From the way I had originally read your description it had sounded to me like you were using extremely heavy neck tension on your testing tool, now I understand that you are using easy-finger-tension which is good.

@Ian to be honest I don't know if the collet die is "great" for neck tension in the context of current F Class technology, it has been ten years since I shot F Class. I will definitely defer to your knowledge and also too to the many real, current F-Class shooters who populate this area and contribute. I was initially not sure of what the level of Ishodu's reloading knowledge was (it now appears to me to be pretty good), so the comments I have made up to this point were in the context of possibly dealing with brass of unknown provenance, irregularly lubricated ordinary dies, wildly wrong knowledge of throat length, no idea of whether the bullets are straight or not etc. So I was just trying to get him the the first, pretty easily achievable level of getting say 1.5 MOA at 1000 yards, which is well beyond a "good enough" level to stop waiting around for perfection and move to just-get-out-and-get-shooting. Obviously for top-level competitiveness in F-Class one must and can do a fair bit better than this accuracy level. I just wanted him (and others reading this thread) to know not only what the vital basics are for 1000 yard shooting (use a known good bullet powder and brass, make straight ammo, get good groups at 100 yards, get reasonably good chrono results), but also to know that there are many factors that may be ignored at first (e.g. no need for weight sorting brass, neck turning, primer pocket prep, annealing, trimming pointing or sorting bullets, and many many more good sound advanced loading techniques that are relevant in the the search for a 1/2-minute 1000 yard rifle but will be totally lost in the noise until all the basic stuff is correctly sorted out).

@Ishodu I am interested in seeing how your load development progresses, in particular how quickly you can get a load that shoots ten shots into 3/4" at 100y and has an extreme spread of 45fps or better (you may discover on your next trip to the range that you already are there). That level of rifle+ammo performance is good enough to take you to quite an advanced level of 1000y shooting. Pretty much everything you are doing seems to be well done, my only "complaint" if any would be that you are "wasting" ;-) your time on additional efforts that will give you benefits much smaller than the effort that goes into them.
 
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