Re: 338 Norma Magnum
Greetings to all:
I have been monitoring this thread for a long time, but this will be my first posting. I was monitoring because I had plans to build a long range hunting rifle and news of a new cartridge interested me. I wanted to get things as right as possible before setting them into motion because the total expense of the project places it squarely in the "once in a lifetime" category for me. I have now gathered enough information that I thought it might be of value to some who also follow the thread if I share my findings, decisions, and how I arrived at them.
After watching how frequently people reply to postings from others with questions about what equipment and components they were using for their rifles, I thought I would start with that up front and then get back to how I arrived at this point. So here is where I am:
Action: Stiller TAC338 (I am left handed, actions is on order)
Trigger: Jewell HVRTLS (I will do the install)
Bottom metal/magazine: Seekins Precision
Picatinney rail: Seekins Precision (30 moa offset)
Scope rings: Seekins Precision (4 screw, 34mm, high)
Scope: Precision Heritage 5-25x56
Scope accessories: mil-spec Angle Degree Indicator/Badger Ordnance Gen I or Gen II mount; Anti-Cant Device (34mm, black)
Stock: Manners Composite Stocks MCS-T4 (incl. 90% carbon fiber option & (2) flush cups w/swivels; black; I will do Marinetex bedding)
Stock accessories: Seekins Precision Sling Rail System; Rock Creek Bipod
Barrel: Bartlein stainless steel (28.00 finished length; 1.35 dia @ receiver face; 0.900 dia @ muzzle; 5R rifling; fluted)
Barrel accessories: I have not yet decided whether to include a muzzle brake, or which it might be. If I do, I would have it removable/replacable with a sleeve to protect the barrel threads. Essentially, I do not like brakes because of the noise issue, but recoil may change my mind.
Selection of the components of the rifle was based upon prior experience, combined with a careful review of the available information of the current marketplace for components that might be found on this type of rifle.
So, on to the .338 Norma. Early posts to the thread reflected a lot of confusion re. whether the cartridge existed, what the case looked like, why it may have been designed, etc. . . . all based upon a general lack of hard information available to most people at that time. There were also a number of posts that had erroneous information that probably mislead some who read them. For instance, the case was based upon a Dakota (probably the .330), the advantage of the .338 Norma was that it could be set up in a standard length action, etc.
Pictures gradually began to be seen on the thread, and the first one that cleared up a lot of prior mis-information was posted by JustRoy on 7/21/08 @ 8:13PM. It showed loaded rounds of a .338 Lapua and .338 Norma side-by-side, of essentially identical length. It was becoming clear that the reason for the .338 Norma was to allow the use of the long 300 grain bullets, without the necessity of seating them deep into the powder space of the case because of limitations on COAL imposed by available magazines.
There was a lot of discussion about the Norma case design possibly having as much as 20% less volume than the Lapua, so how could it hope to provide anywhere near the same performance, regardless of where the bullet was seated? By now, many of you who read this will have had these questions answered in your own minds, but others may still be wondering about the details. So here is the summary of what I found:
1. Both the Norma and the Lapua are based upon the .416 Rigby case and have essentially identical case heads.
2. The Norma is not simply a shortened and "improved" Lapua, in the sense of an Ackley version of a case. The body of the Norma case is straighter (less taper) than the Lapua. It is 0.222 shorter than the Lapua, but its neck is slightly longer (0.354 vs 0.327). Unlike indicated in some earlier posts, the Norma shoulder is steeper, but just barely (20.5 deg per side vs 20 deg per side for the Lapua).
3. The primary advantages of the Norma would seem to be a shorter powder column (claimed to have higher efficiency), and the ability to seat very long bullets farther forward where they do not encroach on the powder space of the case.
4. But what about actual effective case volume? This one takes a bit of explanation. QuickLoad lists the case volume to overflowing for the Lapua as 108.0 grains of water. I just took a never fired Lapua case, stuffed the primer pocket with modeling clay, and weighed it to the nearest 0.001 gram (21.854 grams). Then I filled it with water to the lip of the neck and re-weighed it. (29.101 grams) The difference of 7.247 grams is the water, and that converts to 111.84 grains. Note that this was a Norma brand .338 Lapua case. I don't know what brand of case was referenced by QuickLoad. I don't have an empty .338 Norma case to weigh with and without water to find true volume (possibly another reader can provide that information?).
For the sake of our comparison we can pretty much eliminate the need to weigh both cases for the time being if we make a couple of reasonable assumptions: A. Both the .338 Lapua case I weighed, and all .338 Norma cases are made Norma. B. We can assume that the structure of both cases as made by Norma are similar (thickness of the web in the case head, thickness and taper of the sides of the cases, etc.) If we make that assumption for the sake of comparison, we can simply compare the volumes calculated for the outside dimensions of the two cases, correct those values by subtracting the volume of the bullet shank seated in each case, and by correcting the volume of brass due to the shorter body of the Norma case.
Without going through the calculations here, I can say that if both the .338 Lapua and the .338 Norma have bullets seated to a 3.65 COAL (max. for a current AICS magazine), the volume difference would be 0.89 grains of water (Lapua larger). In other words, the effective volumes are the same!
There is now, however, another factor brought into the situation that provides something additional to consider: magazines that handle longer cartridges are becoming available. I have heard that AICS has mags coming that go out to 3.800. Wyatt mags have the same inside dimension. Glen Seekins told me that his magazines are 3.94 inside, so a COAL of 3.90 gives sufficient space for good feeding.
With that in mind, we can go back to the posts in the thread that ask, "if longer mags are becoming available, then the limitation of needing to stuff long bullets too deep into a .338 Lapua case is no longer an issue. So now what is the advantage of the .338 Norma?" Now I needed to look at some more details.
One of the stated advantages of the Norma is the fact that it was designed to be used to best advantage with the very long 300 grain bullets. There are currently two bullets available that fit that description (Sierra MK and Lapua Scenar), and there will very shortly be another (Berger VLD). It is the "not-quite-yet-available" Berger that has my attention. The VLD designs have several notable points: 1. They are extremely efficient performers to very long ranges. 2. The bullets are very long for their caliber, and 3. They have a reputation for a particular sensitivity to being seated at just the right distance off of the rifling to provide their best performance. That meant that if I hoped to use the 300 grain VLD Bergers in my new rifle, I would likely need to have a reamer cut with a throat specifically designed for them. And information directly from Bryan Litz at Berger confirmed that a chamber so cut could not be expected to be usable with a 250 grain VLD, which means that one needs to know what one wants before it is purchased! Now, you will hear some say that although the 300 grain bullets perform better ballistically, a 250 grain bullet is faster and has essentially identical total drop to 1,000 yards. However, in these days of laser rangefinders that can quickly tell you ranges at 1,000 yards within 1 yard (!) identical total drop is a much less important issue than wind drift. Wind remains the most difficult factor to quantify, as well as the factor subject to variability in real time. And bullets with higher ballistic efficiency are effected least by wind. Thus, 300 grain bullets, with their higher efficiencies, are the definite choice over the 250's.
In my discussions with Bryan Litz, he also indicated that the best location for bullet seating would be expected to be found in the range from 0.000 (touching) to 0.100 off of the rifling. He also indicated that if I designed the throat of the reamer such that the ogive of a 300 grain VLD bullet just touched the rifling when the heel of the bullet was 0.100 ahead of the base of the neck, I would then have the ability to move it back as much as 0.100 in testing for the most accurate seating location and still not have anything but the boat tail encroaching into the powder space. If that is done, the COAL for that bullet seated to touch rifling in a .338 Norma case would be 3.894. However, in the Lapua, even if I seat the bullet to use the full available 3.900 COAL of the Seekins magazine, the full boat tail and 0.097 of the bearing surface will protrude into the case. In this scenario, the volume advantage of the Lapua (calculated in the same manner as previously) actually increases to 2.06 grains . . . still not very much.
So what did I learn from this? If I accept that the shorter powder column of the Norma is more efficient as claimed, the small difference in effective volume between the two cartridges may be a wash, giving equivalent performance between the Norma and Lapua. Powder charges for either should vary by amounts no larger than the differences in their case volumes. Recoil? I'm sure I couldn't feel any difference (both hit hard). Accuracy? I can't say with certainty, but I seem to have read somewhere that the Lapua is also pretty freakin' accurate, eh?
The single confounding factor in this is the statement that the great performance of the Norma was due in part to factory loads being stuffed with a powder that is not available to the general public. This would seem to be a situation similar to that of the 6.5 Creedmoor. My assignment of value of this revelation is "LESS THAN ZERO". Any cartridge that needs to use proprietary powder in order to achieve its highly claimed performance is suddenly of decreased interest to me. Would I use factory loaded .338 Norma? Well, let's see, is it available with the 300 grain Berger VLD bullet? Would the bullets be seated at the most accurate depth for my particular rifle? Does it cost the same as handloaded ammunition? The answer to those, and other similar questions is of course, NO! Those are some of the significant advantages prized by handloaders. In rifles of this category and performance level, I would venture to say that, outside of military and LE users, few others rely on factory ammunition.
And, here's my final tie breaker: Always, in all of my reading, research, and personal experience, I have found nearly unanimous preference for Lapua brass over Norma. Beyond numerous quality issues, this is particularly significant to me when I factor in the predicted number of times it can be reloaded before needing to be replaced. So, with the availability of long magazines, the minimal expected differences between the .338's Lapua and Norma from a performance perspective, and the significantly better reputation of Lapua brass, my rifle is "currently" scheduled to be a .338 Lapua. Of course, since I do still have a little time before I need to order a reamer, I could still "potentially" change my mind. I just wish that someone could provide accurate measured information on the true full to overflowing case volume for the .338 Norma, as well as confirmation that the Norma brass can be loaded 15 or more times before replacement. I suppose if I go ahead with the Lapua and am later proven wrong, I can always have the next barrel on my rifle chambered in .338 Norma. But then, how far wrong could I be . . . at 1,000 yards or more?
Just my take on things.
" then I might swing to the .338 Norma.................338 LM is reletavily easy in Australia as we can get brass etc. But Have none is sayiong that it can be made from .338 LM at any rate.
