Lapua .338 LM vs. Peterson .338 LM

[Supersubes]

Readers digest version: Peterson .338 Lapua brass is stronger, more uniform, has more internal capacity, and is much cheaper than Lapua brand .338 Lapua brass.



For this test I took ten random pieces each of lapua and Peterson .338 lapua brass. The rifle is an AI AXMC .338, with the factory 5R bartlein. I rethreaded the muzzle and installed a Muzzle brakes and more brake. Excellent brakes, and you cant beat the price. I lost about a half an inch of barrel(about 26.5" now). I didn't want to waste flatline bullets on this test, so I used 250 Scenars and jumped them .030". The load is detailed at the top of pic 2, but it used H1000 and 215M primers. No sorting or truing of any type was performed beyond FL sizing and inside neck chamfer.


This pic details some averages of the 10 cases for each brand, in various measurements. Note that the Lapua brand is thicker in the web area. I was pretty certain after this measurement that I'd have trouble with the Peterson. If you compare most Lapua brand cases, they put more meat in this area as compared to domestic cases. The Peterson has a slightly larger extractor groove diameter than the Lapua, but a slightly smaller rim. Also of note, the Peterson cases would only fit in my redding shell holder, and none of my RCBD shell holders. The headspace measurement was taken with a Hornady .420 comparator. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/ac86aea125d93853a56e194e5ee76f28.jpg"}[/IMG2]










I couldn't find my previous load data for the 250 Scenars and H1000, so I used some 250 SMK data. These ended up being MUCH faster/hotter than the 250 SMK loads. These are hotter loads than I would run day to day. Depending on the manual you're looking at, these are several grains over their listed maximums(Hodgdon, Hornady). Please do not use this load data with out working up to it.



On to the good stuff. I had two fouler rounds at 94 grains, which left me with 18 record cases. The pic below will mostly speak for itself. The highlighted areas are Peterson brass. from left to right: charge weight, velocity, before and after expansion plus the actual expansion(very small numbers), then case weight and water weight. Note the amount of expansion in the 94 grain lapua brand loads. .0009"-.001". Now scroll down a bit and look at how the Lapua brand progresses, to a max of .0013"-.0016". While your down at the bottom, compare that with the maximum Peterson loads. The Peterson hardly grew at all, and really didn't progress at all. There is a little more capacity in the Peterson, so they run slower at the same charge. If you want an apple to apple comparison, look at shots 14 and 16 for example. The Lapua grew three times more at the same velocity. The Peterson isn't just stronger, it's a lot stronger. At the far right I added case weights and water weights of those cases. At the bottom of this pic are the case and water weight E.S. numbers. Without doing the math, the Peterson case spreads are a mere 25% of the Lapua cases. That is a lot better. No need to sort these at all. When I used to case sort, my individual batches weren't as tight as this. I measured some cases for length so I'd have something equal for the water weight test. I would have trimmed them equal if needed, but they were all within .0015" of one another. I thought that was good enough. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/1b91c6cbad0289e21c3cfa17077bcf2a.jpg"}[/IMG2]












Here are all the record cases, as they were fired (left to right and top to bottom). My rifle makes two distinctive markings on case heads, even at fairly low loads. One edge of the ejector hole usually presents a half moon shape. Also, the ejector on an AXMC is nipple shaped and pointy, which causes a little gouge in every case upon opening the action. After looking at these close-ups, I removed the extractor and rounded/polished it. Hopefully the markings will go away. All of these marks are orientated to 12 0'clock in this picture. While there are no ejector swipes, the ejector marks show up earlier and are far more prominent on the Lapua Brand cases. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/c5099bb20ab6d8555c1b20710c1c2cfb.jpg"}[/IMG2]











This is a close up of the pic above, the 96 grain loads. It could have been better. The Peterson is slightly out of focus, but there isn't really anything to see on them. The Lapua marks are easy to see, even without magnification. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/36c0bb3e27c8ddb070da9cdb4e78a66f.jpg"}[/IMG2]











Below are shots of #16 and #14, the two fastest rounds of the day. These were representative of the other cases at the same charge weight though. Almost nothing to see on the Peterson case below (3052 fps). The center of the ejector is right on the upper left corner of the P in Peterson. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/8fb727053d04e2190d1847b9ca57ac2a.jpg"}[/IMG2]











This is shot 14(96 gr, 3058 fps). Not really a bad mark, but plainly visible without any magnification. Looking at this closer, there is actually a little swiping off the lower edge of the ejector mark. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/1a94c8288e791ad1892bb998bb3f0318.jpg"}[/IMG2]









As I said in my 300wm Peterson test, I'm a huge Lapua fan! I use it in every rifle I can, and plan future builds on the availability of Lapus brass for the intended cartridge. I also view Lapua brand .338 LM brass as pretty much the stoutest case in existence. It just sucks up punishment, and keeps on going. I'm still shocked that the Peterson, with it's slightly thinner narrower base and less overall mass, can actually be stronger than the Lapua brand case. I just went to the Peterson website and put 100 pieces of this brass in a cart, for a grand total of $209.95 shipped. About $40/per 100 pieces cheaper than Lapua brand sale price.

I'll post more as it comes to me, including some better pictures.

Rick Peterson, if you're reading this, please please please make a 300 Norma case that is as strong as your .338 Lapua case!

 

[TripleBull]

It would be interesting to hear your observations on re-priming these cases, assuming you use a press that has good feel. Or maybe the 3rd or 4th re-prime.

 

[Supersubes]

I figured I'd post that info when I got around to reloading those cases. The movement in the case head of the Peterson was so minuscule I don't expect any issues, but I will post the results. Also add that when I primed the case is the first time, the Peterson was noticeably stiffer. When I get home today, I'll jam some primers into that top load and post what I find

 

[Fursniper]

Supersubes, great write up, very revealing, thanks for all that effort! The part that worries me is the Web area/primer pocket durability. This is what usually goes first (at least with my loads, lol). With the Peterson being slightly less robust in that area I'm wondering about the longevity there. Looks like TripleBull caught on to that too. Case necks splitting, case head seperations, never been a problem, but primer pockets have been with other brands of 338 brass. Looking forward to your comparative discoveries & thoughts on this as you get into 4-5 reloads or more with these.

Again, Nice job! The consistancy in weight & volume of the Peterson, less case stretching, hardness, etc, again, all very revealing & encouraging. The superior quality is obviously there, a friend has found this in the Peterson 375 brass too, compared to Bertram brass anyway, Peterson is the clear winner. Lapua is known for tough primer pockets and the meat in the Web area. If the Peterson 338 can hold up to Lapua in that department, we definately have a new Sheriff in town.......

 

[Supersubes]

I pushed out the primers on the 96 gr load cases (6 total, 3 of each brand). Oddly, the peterson primers were easier to push out than the lapua. When pushing new primers in though, the Peterson are noticeably harder to seat, as they were when new. Ive always found 215's on the fat side compared to CCI primers, and my guess is the cci would probably seat with normal pressure. In this case, two of the three primers in the peterson cases have imprints from the ram of my rcbs hand priming tool. I'll take some pics when I get a chance.


It wont be till next week when i get around to firing these again, but i'll be using the exact same cases, with a slightly backed off load. 2950 fps or so. I'll try to adjust the charge upward in the Peterson so they're going the same speed as the Lapua. Then I'll just go to town on them.


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[Supersubes]

I have some updated info from the test brass.

Ive now reloaded the cases for the third time, and I found some interesting things.

For the first go around, I started with the brass which had been fired at 96 grains. I pushed the primers out with a decapping die and measured them for fired headspace. I found that the Lapua were .002 longer than the Peterson. You can see the pics below, but the Peterson grew to my chamber dimension, and the bolt will still close on them in a "touching" fashion. Never more than light pressure to close the bolt. The Lapua on the other hand, being .002 longer, are all a hard close. I decapped the rest of the test sample for both brands and checked headspace. In every case, the peterson is chamber size, and the Lapua is .002 longer. This is a second data point that shows the the Lapua is a softer case(the first was web expansion data above).


Here's where it gets interesting. I use a Redding type S FL sizer in combination with Redding competition shell holders. Given the numbers above. I needed to determine the proper shell holders for each brand, because they were definitely going to be different. I did the Lapua first, and found I needed the +.002 height shell holder for them to properly fit in the chamber, and there is a noticeable shoulder bump at the end of the press stroke. These cases just fit in the chamber. Since the Peterson was so close to chamber size already, I needed the tiniest bit of shoulder bump I could get. I ended up using the +.008 shell holder. The shoulders moved such a small amount, my caliper will hardly pick it up (.0005 graduations).

So the Lapua needs to be run into the die .006 further than the Peterson to make them the same size. For being a weaker material, the Lapua sure is springy!

I reloaded them all and adjusted the charge a half grain higher for the Peterson, since it's got more internal volume. So 91 gr for the Lapua, and 91.5 gr for Peterson. The average velocity for the Lapua was 2882, with a 24 ES, and 9.7 SD. The Peterson was 2877, with 17 ES, and 7 SD. This agrees with first test in virgin form, where the more uniform Peterson had slightly smaller velocity spreads.

As of this writing, I have reloaded this same batch of cases a third time, and found exactly the same relationships with regard to fired size, and sizing requirements. Primer pockets on the lapua are settling in, but very good. The Peterson continue to be a fair bit stiffer than the Lapua to seat the primers.


Here are some pics of the headspace measurements from that first reload session. This is using a .420 hornady tool, so not the correct datum for a Lapua case(.455), but good for a comparative number.

Peterson

Lapua

On a slightly different note, I was able to confirm with Peterson this week that all retail brass comes in these plastic boxes.

This is large primer Creedmoor. I'll be testing these soon, alongside virgin lapua small primer Creedmoor. The small primer version is coming according to Peterson.

Here is some .375 Cheytac brass. Working on building one of these at the moment. This stuff is actually cheaper than Lapua brand .338 brass.

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[Gohring65]

Tag

 

[Fursniper]

Certainly some strong comparative examples & reasoning for the Peterson brass. Thanks Supersubes for the analysis, it's nice to have a viable alternative to the Lapua brass which has been the go-to for so long.

 

[ED_RN]

nice write up with pertinent details...
Peterson and Kinetic Industries are new to the brass market.
And, the feed back is compelling to say the least!

 

[TripleBull]

Good stuff. What are you seeing on target between the two? What distances are you shooting at?

 

[Supersubes]

My desert LR spot has been a hell hole lately, so ive only shot them at 100 meters. No real difference between them at that distance. After this coming weekend they should be up to 6 firings or so. I'll have some neck thickness variation numbers as well.

 

[JWG284]

In for more. I ordered 100 6.5 Creedmoor to neck down to 6mm and turn to .0145. The dry weight on my cases are very consistent. I have not gone through the trouble of measuring water volume.

 

[Fursniper]

Well,the jury is in, at least for me with 338 cases. There's a reason the box they come in says not to fireforming their cases. Because if you do they split open like an over ripe banana. Why? Because they are weak and inferior to Lapua cases which I can fireform into ackley improved cases all day long without a case failure. Maybe for regular loading they are ok but a good friend lost his primer pockets after 1 firing with PCC 300 WM brass so there ya go. We gave it a shot.

 

[Supersubes]

I think what you may have run into is their hardness. They are a fair bit harder than lapua. By the 4th firing, the lapua's harden up to equal where the peterson start at. If you have any more of the peterson, you may try annealing the shoulders before the fire form.

We have a bunch of firing's in 300 wm now, with no issues. Any chance your buddy didn't adjust his charge down for the smaller capacity Peterson cases? Can you post his load? So far, every cartridge of theirs I have has shown smaller capacity than the lapua or domestic counterpart. Than any other make in capacity. Per their engineers, their cases are designed to take a proof load, and still be reloadable.

Sorry they didnt work out for you.

I recently bought some new machines and have been setting my home shop up. A ton of work. Still havent finished all the testing i'd like to do on the various Pererson I have on hand.

 

[Fursniper]

I think what you may have run into is their hardness. They are a fair bit harder than lapua. By the 4th firing, the lapua's harden up to equal where the peterson start at. If you have any more of the peterson, you may try annealing the shoulders before the fire form.

We have a bunch of firing's in 300 wm now, with no issues. Any chance your buddy didn't adjust his charge down for the smaller capacity Peterson cases? Can you post his load? So far, every cartridge of theirs I have has shown smaller capacity than the lapua or domestic counterpart. Than any other make in capacity. Per their engineers, their cases are designed to take a proof load, and still be reloadable.

Sorry they didnt work out for you.

I recently bought some new machines and have been setting my home shop up. A ton of work. Still havent finished all the testing i'd like to do on the various Pererson I have on hand.

Peterson says their cases are already annealed at the factory. They claim the cases don't LOOK annealed (like lapua ones do) due to the high finish polish their cases get, but annealed nonetheless. Besides, the cases split below the shoulder, down the middle in a straight line to about a 1/2" above the web. The case mouth & neck is fine.
I'll see if I can get the load from my friend for his 300 WM cases, it was for a 7mm/300 so it won't be the same as for a 30 caliber.
Anyway, harder or not, they just don't stand up to the fireforming treatment. To bad, I had high hopes for them, their prices were attractive compared to lapua. I even tried hydro forming the Peterson cases prior to firing to reduce much of the stress from the fireforming process but no joy there either. My observation from the hydroforming of lapua verses the Peterson was the Peterson hydroformed MUCH easier then the lapua which would seem to actually indicate that the Peterson was actually SOFTER than the lapua. The lapua cases are difficult to get a good shoulder angle with hydroforming, it just seems the case is too hard. The Peterson cases would form right up with a much more finished 40 degree shoulder, which again would seem to indicate a more softer & malable case.

 

[Ta406]

I think what you may have run into is their hardness. They are a fair bit harder than lapua. By the 4th firing, the lapua's harden up to equal where the peterson start at. If you have any more of the peterson, you may try annealing the shoulders before the fire form.

We have a bunch of firing's in 300 wm now, with no issues. Any chance your buddy didn't adjust his charge down for the smaller capacity Peterson cases? Can you post his load? So far, every cartridge of theirs I have has shown smaller capacity than the lapua or domestic counterpart. Than any other make in capacity. Per their engineers, their cases are designed to take a proof load, and still be reloadable.

Sorry they didnt work out for you.

I recently bought some new machines and have been setting my home shop up. A ton of work. Still havent finished all the testing i'd like to do on the various Pererson I have on hand.

How did you come across 300WM brass? I keep checking their site and it always says "Coming Soon".

 

[Supersubes]

A gunsmith friend of mine got a quantity of them for testing after SHOT. I posted the write-up in this sub forum.

 

[Dave62677]

i'm on my 8th load, primer pocket still gtg

 

[Bulletsmith]

This is good to hear, I am patiently waiting on a .338L barrel and in the meantime I bought a box of Peterson .338 brass and I can tell you that for such a large case the weight consistency is around 1.5gr. on the 50 cases in the box. Now if I could just get my barrel.

 

[aspen69]

Did an evaluation for Peterson on their .300 Norma brass. I came out superior to the Norma brass in every way. Unfortunately it still hasn't made it to the market.

 

[jb1023]

Supersubes, any chance you plan to do a head to head like this with ADG brass? I started one between ADG and Lupua in 6.5CM but it was no where near as thorough and I sold the Lapua before I fired off a single round so it ended at the initial measurements.

 

[Dave62677]

my 8th load on 338lm peterson brass, trimmed 2 times, anneal 5 times. my paperclip told me still go to go on 9th load, primer pocket still happy

 

[wind gypsy]

Did an evaluation for Peterson on their .300 Norma brass. I came out superior to the Norma brass in every way. Unfortunately it still hasn't made it to the market.

Did you post your findings anywhere? I'm anxiously awaiting 300 Norma brass as well.

 

[Tjfarmer]

It would be interesting to hear your observations on re-priming these cases, assuming you use a press that has good feel. Or maybe the 3rd or 4th re-prime.

Or the 15-16th reload. Usually I give up on my Lapua brass cause of the “frost” line, not the primer pockets. What’s peterson run a 100? I just bought Lapua in a weird sale I found for 214. Good to hear it looks pretty promising, Love good choices.

 

[BuLLet]

Any updates on the life of Peterson, I'm considering ordering for 338 and 300 Norma Magnum.

 

[George F]

Readers digest version: Peterson .338 Lapua brass is stronger, more uniform, has more internal capacity, and is much cheaper than Lapua brand .338 Lapua brass.



For this test I took ten random pieces each of lapua and Peterson .338 lapua brass. The rifle is an AI AXMC .338, with the factory 5R bartlein. I rethreaded the muzzle and installed a Muzzle brakes and more brake. Excellent brakes, and you cant beat the price. I lost about a half an inch of barrel(about 26.5" now). I didn't want to waste flatline bullets on this test, so I used 250 Scenars and jumped them .030". The load is detailed at the top of pic 2, but it used H1000 and 215M primers. No sorting or truing of any type was performed beyond FL sizing and inside neck chamfer.


This pic details some averages of the 10 cases for each brand, in various measurements. Note that the Lapua brand is thicker in the web area. I was pretty certain after this measurement that I'd have trouble with the Peterson. If you compare most Lapua brand cases, they put more meat in this area as compared to domestic cases. The Peterson has a slightly larger extractor groove diameter than the Lapua, but a slightly smaller rim. Also of note, the Peterson cases would only fit in my redding shell holder, and none of my RCBD shell holders. The headspace measurement was taken with a Hornady .420 comparator. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/ac86aea125d93853a56e194e5ee76f28.jpg"}[/IMG2]










I couldn't find my previous load data for the 250 Scenars and H1000, so I used some 250 SMK data. These ended up being MUCH faster/hotter than the 250 SMK loads. These are hotter loads than I would run day to day. Depending on the manual you're looking at, these are several grains over their listed maximums(Hodgdon, Hornady). Please do not use this load data with out working up to it.



On to the good stuff. I had two fouler rounds at 94 grains, which left me with 18 record cases. The pic below will mostly speak for itself. The highlighted areas are Peterson brass. from left to right: charge weight, velocity, before and after expansion plus the actual expansion(very small numbers), then case weight and water weight. Note the amount of expansion in the 94 grain lapua brand loads. .0009"-.001". Now scroll down a bit and look at how the Lapua brand progresses, to a max of .0013"-.0016". While your down at the bottom, compare that with the maximum Peterson loads. The Peterson hardly grew at all, and really didn't progress at all. There is a little more capacity in the Peterson, so they run slower at the same charge. If you want an apple to apple comparison, look at shots 14 and 16 for example. The Lapua grew three times more at the same velocity. The Peterson isn't just stronger, it's a lot stronger. At the far right I added case weights and water weights of those cases. At the bottom of this pic are the case and water weight E.S. numbers. Without doing the math, the Peterson case spreads are a mere 25% of the Lapua cases. That is a lot better. No need to sort these at all. When I used to case sort, my individual batches weren't as tight as this. I measured some cases for length so I'd have something equal for the water weight test. I would have trimmed them equal if needed, but they were all within .0015" of one another. I thought that was good enough. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/1b91c6cbad0289e21c3cfa17077bcf2a.jpg"}[/IMG2]












Here are all the record cases, as they were fired (left to right and top to bottom). My rifle makes two distinctive markings on case heads, even at fairly low loads. One edge of the ejector hole usually presents a half moon shape. Also, the ejector on an AXMC is nipple shaped and pointy, which causes a little gouge in every case upon opening the action. After looking at these close-ups, I removed the extractor and rounded/polished it. Hopefully the markings will go away. All of these marks are orientated to 12 0'clock in this picture. While there are no ejector swipes, the ejector marks show up earlier and are far more prominent on the Lapua Brand cases. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/c5099bb20ab6d8555c1b20710c1c2cfb.jpg"}[/IMG2]











This is a close up of the pic above, the 96 grain loads. It could have been better. The Peterson is slightly out of focus, but there isn't really anything to see on them. The Lapua marks are easy to see, even without magnification. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/36c0bb3e27c8ddb070da9cdb4e78a66f.jpg"}[/IMG2]











Below are shots of #16 and #14, the two fastest rounds of the day. These were representative of the other cases at the same charge weight though. Almost nothing to see on the Peterson case below (3052 fps). The center of the ejector is right on the upper left corner of the P in Peterson. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/8fb727053d04e2190d1847b9ca57ac2a.jpg"}[/IMG2]











This is shot 14(96 gr, 3058 fps). Not really a bad mark, but plainly visible without any magnification. Looking at this closer, there is actually a little swiping off the lower edge of the ejector mark. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"https:\/\/uploads.tapatalk-cdn.com\/20170503\/1a94c8288e791ad1892bb998bb3f0318.jpg"}[/IMG2]









As I said in my 300wm Peterson test, I'm a huge Lapua fan! I use it in every rifle I can, and plan future builds on the availability of Lapus brass for the intended cartridge. I also view Lapua brand .338 LM brass as pretty much the stoutest case in existence. It just sucks up punishment, and keeps on going. I'm still shocked that the Peterson, with it's slightly thinner narrower base and less overall mass, can actually be stronger than the Lapua brand case. I just went to the Peterson website and put 100 pieces of this brass in a cart, for a grand total of $209.95 shipped. About $40/per 100 pieces cheaper than Lapua brand sale price.

I'll post more as it comes to me, including some better pictures.

Rick Peterson, if you're reading this, please please please make a 300 Norma case that is as strong as your .338 Lapua case!

I got 250 Peterson 338 LM cases in a bulk pack. They never shot well. Lapua shot a lot better. Tried turning the necks on the Petersons. Found them uneven with lots of run out. Called them they seemed disinterested in helping me. Use Lapua brass exclusively now. Much better quality control

 

[secondofangle2]

It is silliness to think that a newcomer can top Lapua brass. The bar is high for evidence, not just some measurements and inferences. The community has spoken on this: Lapua is the standard, *especially* with 338LM

How much $$$ do you think Lapua and Peterson have each put into R&D and metallurgy? This whole post is missing the forest while inspecting leaves under a microscope

 

[George F]

Lapua clearly make the best 338LM brass. Tried Peterson. Necks were not straight or of uniform thickness. Called them and they didn’t seem to care.