Lapua .308 Small vs Large Primer

[dcali]

I know a lot of folks use the small primer brass to get a little more case life/pressure out of the .308. But what does that mean in terms of practicality? How much more velocity can you run in a small primer case vs a large primer? What am I giving up by not using the Palma brass? I'm especially interested in experiences with the heavies - the 200-215's.

 

[Scott Harris]

I don't get any extra velocity with palma brass, I get many more reloads: 10-12 for LR and 20-30+ for Palma with the same velocity. The large rifle primer has more energy than the small rifle primer. I have to lower my powder charge by about 1/2 grain when switching from small primers to large primers to maintain the same velocity. Hope that helps.

On a related note, I am on reload #31 with my current batch of Palma brass...and this is running the Berger 185 LRBT at 2800fps from a 32" barrel. Primer pockets still going strong!

 

[Shynloco]

Hey Guys,
Since we're talking "practicality," I'd be more interested in accuracy down range than how much longer case life I get. To clarify, do you get better accuracy using the Palma brass and at what distance do you note improved accuracy? I get the pressure increase stuff but please translate that to accuracy. Got me curious. Thx.

Alex

 

[dcali]

That's quite a bit of difference in life. Have you experienced anything approaching erratic ignition? That's primarily what's been keeping me from trying it. Just doesn't seem worth it for a potential accident.

 

[Laurie]

Alex, it's not so much a matter of 'accuracy' (being pedantic, we're actually talking 'precision'). Large and small primer Lapua 308 brass is in my experience with several recent lots, to all intents and purposes identical, primer pocket and flash-hole dimensions aside. That is, they have the same internal (water) capacity, same weights, same neck thickness. There are good production lots, not so good, and downright superb in both types.

So, all other things being equal, they'll shoot same size groups in a given rifle with a given powder / bullet combination with a bit of charge weight adjustment as Scott Harris says - ~ a half grain.

The reason the Palma case was developed and adopted and has been allowed to use the the closely guarded 'Palma' name is that the company was asked to produce modern copies of the old Remington UBBR brass by the US Palma teams. The raison d'etre not being to produce higher MVs with the usual 155gn Sierra MK + H. VarGet combo, but to reduce MV spreads and ES values. When you're shooting a ballistically marginal bullet for 900 / 1,000 / 1,100 yards competition at ~2,950 fps in some of the hardest fought international shooting matches around, you want as small a velocity spread as possible. Variations = Elevations in any very LR shooting, but especially when your bullets are transonic and maybe even subsonic at the longest distance. That was the objective and the trial Lapua cases produced the goods, the US Palma teams adopting it, and Lapua putting it onto general sale a year or so later, also permitted to use the 'Palma' name as a thank-you. In Palma loads, ES values are reduced by a third or more over standard LRP brass.

It also works in FTR where people are developing loads that often produce single-figure spreads - that's ES, not SDs I'm talking here. On top of that, some hefty loads are being used successfully to get some seriously high MVs with all bullet weights. And the cases last too. They ARE much stronger in the case-head area than their LRP siblings, but I have a suspicion that the small flash-hole and different primer flash characteristics also change the early charge burn behaviour in some beneficial way. Or, maybe not ... and people are just running near proof loads and getting away with it.

Even at some of these very warm loadings, brass life is very good. I know people well into the teens of firings with Palma brass at MVs that 308 simply shouldn't be able to produce and they've yet to scrap a case except those that they over-cooked in load development. FTR shooters have suddenly become very interested in annealing - they didn't need to 'Before Palma' as pockets opened up and the case was scrapped before work hardened shoulders and necks became a serious issue.

I'd say that Palma brass adds 50-100 fps MVs for 155s. So far as the heavier bullets and slower burning powders go, I don't know anybody shooting 185-215s at GB national level who still uses standard brass. I can't say what Palma brass is 'worth' here, because there is little LRP brass data around now to provide comparisons and people were well into using Palma cases before the 200-230gn Hybrids appeared.

Another pointer to their worth with 'heavies' is that there is also 100% adoption by GB and GB Commonwealth 'Match Rifle' competitors. This is a 1,000 yard plus discipline for the 308 but shot with a lighter barrel than FTR and other differences, the main one being the use of the standard Fullbore LR target centre with a 1-MOA 'V', 2-MOA 'Five' and so on. Where ranges allow, MR is shot at up to 1,500 yards such as in international matches in New South Wales, Australia a few years back. These guys throat their chambers RIGHT out and use some fearsome heavy VLD / Hybrid loads - velocity is king in this discipline.

Downsides? If ignition is difficult - a hard to ignite powder in cold conditions - the performance may fall right off. I have seen some loads that simply didn't perform in temperatures just over freezing, yet they'd be OK with a powder from the same company - eg Viht N140 performing poorly, but N150 being OK, in a side by side test session. in theory, they shouldn't work well with older ball powders, yet in side by side tests I got higher MVs and smaller ES values from a Hodgdon H414 load with the Palma brass over standard brass with F210Ms on a chilly winter day - the total opposite of what I'd expect.

The other pointer to their benefits is that in some parts of the world, there is a thriving out of season activity in reforming Palma 308 to other calibres - 260 Rem, 7mm-08, 6.5mm Hornady Creedmoor even - for top velocity and precision competition or LR sporting loads. The Kiwis and Aussies seem to have latched onto the benefits in cartridges like 260 Rem much more than us Brits - can't speak for US tactical and sniper / F-Class etc shooters. It may be that there is a lot less use of the larger case sevens in these countries, so there is greater need to optimise the smaller numbers' performance.

 

[Shynloco]

Laurie,
WOW! That was quite an explanation for which I am appreciative. I don't possess the vast knowledge you've displayed in your response so I'm going to have think about a lot to ingest all that you've written. Now admittedly, I've never used any Palma Brass, but have also stuck pretty much with 168's for short distance shooting. I tried a few loads (in regular Lapua Brass) that Kevin Thomas suggested, but didn't have great luck with the 155 @ 100 yds. But that hasn't stopped my continued interest in areas of reloading and shooting where I haven't been successful. So I sincerely thank you for the detailed explanation and teaching me the benefits of using Palma Brass and the reasons why others have found success, even in other countries. Also good to know those who possess such vast knowledge are willing to take the time and share with others, not as well informed, but eager to learn. Thanks again Sir!

Alex

 

[Laurie]

Alex, for short range 308 shooting, there is no great benefit in the Palma brass if you're using 'sensible' loads and pressures. Group size is everything at 100-600 yards, BC is not very important, and ES / SD values don't count for anything.

So, if you get good results with standard brass and 168s, just stick with them. FWIW, it seems that if there is a temperature related problem with Palma cases, it's at temperatures under 5-deg C (low 40s F) that they appear. In the UK we shoot all year round with our mild winters by North American standards, but we might shoot on a day with freezing air temps or barely above that, and I prefer to avoid Palma brass loads on those days just in case.

In any events, the US Palma Teams captains and Lapua must be commended for putting so much effort into this development. If you hunt around the US Rifle Teams' Long-Range Forums enough, you'll find several threads on this subject explaining the background.

http://www.usrifleteams.com/lrforum/index.php?

It wasn't at all uncontroversial. Many older hands had experience of the old 1960/70s Remmy UBBR small primer / small dia. flashhole cases, and were very dubious because of ignition problems. However, it seems SR Magnum / BR primers and/or powders used in 308 Win have improved in the last 30 years as few if any of these fears have been realised in practice. Lapua still (sensibly) says 'not for hunting', although that should really be changed to 'not for winter hunting'.

 

[Laurie]

On a related note, I am on reload #31 with my current batch of Palma brass...and this is running the Berger 185 LRBT at 2800fps from a 32" barrel. Primer pockets still going strong! [Scott Harris]

That IS impressive Scott, though I'm not too surprised. I likely have enough Palma cases left from all the effort involved in the F-Class World Championships at Raton in 2013 and the run-up to it with team practices etc to see me out to when I 'pop my clogs' (as they say in my current abode of Yorkshire in northern England) plus another 50 years in the afterlife. Having just acquired a UK manufactured annealing machine, it's a case (no pun intended) of getting on and annealing several hundred of the things.

Just a shame I mostly shoot F-Open these days!

 

[dcali]

My understanding is basically what Laurie laid out in that lengthy post - that the initial aim was to aid optimal ignition for warm summer days. However, it seems that folks have figured out that the small pocket leads to a stronger case head which is more tolerant of pressure. I assume that means people are running "near proof" loads and getting away with it because the brass is stronger.

There's nothing wrong with that in and of itself - if the system is built for it. But it does make you think a bit. How much is too much? Does a spec even mean anything when you're running 215's out to a OAL that's well beyond spec through a giant action? To be honest, I hope Lapua did their homework before putting these on the market...

 

[Scott Harris]

Hey Guys,
Since we're talking "practicality," I'd be more interested in accuracy down range than how much longer case life I get. To clarify, do you get better accuracy using the Palma brass and at what distance do you note improved accuracy? I get the pressure increase stuff but please translate that to accuracy. Got me curious. Thx.

Alex

I have not seen one bit of difference in accuracy, SD, or ES between LRP & SRP 308 brass...just brass lasting a lot longer. At the 2014 Berger SWNs, I used LRP brass on two days and SRP brass on two days....no difference on paper.

 

[6BRinNZ]

I don't get any extra velocity with palma brass, I get many more reloads: 10-12 for LR and 20-30+ for Palma with the same velocity. The large rifle primer has more energy than the small rifle primer. I have to lower my powder charge by about 1/2 grain when switching from small primers to large primers to maintain the same velocity. Hope that helps.

On a related note, I am on reload #31 with my current batch of Palma brass...and this is running the Berger 185 LRBT at 2800fps from a 32" barrel. Primer pockets still going strong!

Were you getting 10 -12 @ 2800 for LR? Would that be unique to the bore/groove, powder and HBN coatings for you?

I'm asking as I would be happy to get 10 - 12 @ 2800 with LR....as in I'm nowhere near that now with case life.

 

[Scott Harris]

I don't get any extra velocity with palma brass, I get many more reloads: 10-12 for LR and 20-30+ for Palma with the same velocity. The large rifle primer has more energy than the small rifle primer. I have to lower my powder charge by about 1/2 grain when switching from small primers to large primers to maintain the same velocity. Hope that helps.

On a related note, I am on reload #31 with my current batch of Palma brass...and this is running the Berger 185 LRBT at 2800fps from a 32" barrel. Primer pockets still going strong!

Were you getting 10 -12 @ 2800 for LR? Would that be unique to the bore/groove, powder and HBN coatings for you?

I'm asking as I would be happy to get 10 - 12 @ 2800 with LR....as in I'm nowhere near that now with case life.

I don't know the answer for sure, but we use .175 FB, HbN-coated bullets, and a 32" barrel. Perhaps all those little things add up.

 

[mysticplayer]

My understanding is basically what Laurie laid out in that lengthy post - that the initial aim was to aid optimal ignition for warm summer days. However, it seems that folks have figured out that the small pocket leads to a stronger case head which is more tolerant of pressure. I assume that means people are running "near proof" loads and getting away with it because the brass is stronger.

There's nothing wrong with that in and of itself - if the system is built for it. But it does make you think a bit. How much is too much? Does a spec even mean anything when you're running 215's out to a OAL that's well beyond spec through a giant action? To be honest, I hope Lapua did their homework before putting these on the market...

It is not for Lapua to regulate but the handloader. If Lapua was a US firm, they would never make brass this strong. The lawyers would be all over the engineers to tone down the brass so it will expand at sensible pressures. Just look at how many US brass have been neutered over time.

For decades, the brass and primer were the ways handloaders viewed pressure signs - right or wrong, it gave in indication of what was happening. Now with super strong brass, small primers, and vault tight actions, all those pressure signs can be masked until handloader is approaching "lift off".

Steel used in custom actions is not really different then in factory actions. And when they are dimensional clones, similar in strength as well. I remember seeing tests done at White labratory on pressure testing receivers.

At what we consider magnum pressures, the actions survived firings in the hundreds of thousands. Essentially, something would wear out before the steel.

Ramp up the pressures to proof and the life plummeted to only a fraction of the lower pressure. That was a sobering report for me and I have kept an eye on my receivers and pressures ever since.

There is nothing wrong with the palma Lapua brass in and of itself but it does let shooters reach regular operating pressures far and beyond what is considered normal.

If there are no pressure signs, there must be no pressure.... pretty foolhardy statement.

I threw this out there years ago and no one seems to have been up to the challenge. Put a strain guage on these supersized 308 loads and actually see what the operating pressures are.

If we are around the 65K PSI range, all good. If more like 80K PSI, are we just waiting for an accident to happen?

YMMV...

Jerry

 

[Laurie]

If we are around the 65K PSI range, all good. If more like 80K PSI, are we just waiting for an accident to happen?

Jerry, I'd say the pressures are much closer to 65,000 than 80,000. QuickLOAD estimates ~67,000 psi to break 2,900 with the Juggernaut with RS52, and that's an estimate not real life.

One does see high pressure signs with Palma brass. It's only primer appearance that's different / less affected. If pressures get out of hand, the bolt handle becomes hard to lift and primary extraction effort rises noticeably, well before the primer blows. The other signs such as case-head extrusion / markings are there too. I'm talking well cut chambers and RPA, Stolle, BAT, and Barnard actions too. The fact that the people I have in mind not only manage to avoid problems over season-long match fixtures, but are running double-figure firings cases too is encouraging. One guy who runs his FTR loads way, way above mine told me he scraps his Palma cases at 10 firings, not because he can find anything wrong with them, more that he just can't believe that they can still work well (and safely) with that number of hot loadings.

It's not 308 Palma that frightens me in this respect, more 6.5X47L where one seems to go straight to the blown primer stage without any advance warning. Some of the Varget + 130gn loads I see keen fox-shooting types in the UK quoting on forums produce estimated PMax values in QuicklOAD that do hit the 80,000 psi mark. The MVs these guys claim from short barrels are also in line with this sort of pressure level.

 

[dcali]

My concern is this: How much knowledge do we have on the safety margin between obvious pressure problems - stuck bolts, extruded case heads, etc and ruptured barrels. We used to be able to rely on brass to give up the ghost before things got crazy. Is that still true? I don't have the knowledge to say, but people being what they are, it would be nice to know.

It seems reasonable that the pressures we knew were safe in the 50's might be overly conservative in modern hulk-like actions. But I sure would like to know what a good upper limit is. That's what I mean by "I hope Laupa did their homework". I hope they looked into action strength vs brass strength in at least some detail, as opposed to just releasing small primer brass just because folks wanted it. Yes, it's not their fault if people do stupid things, but it would be nice to know that if the idiot next to me chooses to do so, he'll just lock up his bolt and not blow it up! It's a tragedy that fear of liability is probably reducing the flow of this sort of information, but that's another topic entirely.

 

[dcali]

As a related question, for those who use QuickLoad, what are the pressure estimates that result in unacceptably short brass life for large primer brass? Will 65,000 do it? 75,000? Just curious.

 

[Marksman63]

Just to remember that the Italian Proof Bench certifies and marks tested rifles after shooting special cartdriges delivering 50% over max pressure. That means even COTS modern rifles can handle up to 80/90 kpsi (not forever!, of course)

 

[Down South]

I'm not as adventurous as you boys, my loads are running 58K to 63K and thats good enough for me.

 

[6BRinNZ]

My concern is this: How much knowledge do we have on the safety margin between obvious pressure problems - stuck bolts, extruded case heads, etc and ruptured barrels. We used to be able to rely on brass to give up the ghost before things got crazy. Is that still true? I don't have the knowledge to say, but people being what they are, it would be nice to know.

It seems reasonable that the pressures we knew were safe in the 50's might be overly conservative in modern hulk-like actions. But I sure would like to know what a good upper limit is. That's what I mean by "I hope Laupa did their homework". I hope they looked into action strength vs brass strength in at least some detail, as opposed to just releasing small primer brass just because folks wanted it. Yes, it's not their fault if people do stupid things, but it would be nice to know that if the idiot next to me chooses to do so, he'll just lock up his bolt and not blow it up! It's a tragedy that fear of liability is probably reducing the flow of this sort of information, but that's another topic entirely.

What is the difference between SRP brass and pressure for .308 vs the 6br with respect to safety and how shooters are running them?

The real issue here is the larger shooting community have no way of knowing what the pressure value is - we can only look at symptoms and guess.

 

[Laurie]

If you go back far enough, a lot of loads were limited by the much smaller range of propellants, also the typical factory rifle (and even most competition rifles) of the time had such a poor lockup that high pressures saw groups open up massively, also there was real difficulty in opening the bolt. Primer leaks were likely much more common than nowadays too.

There were people building stuff and loading cartridges though that did run at really high pressures. Mic McPherson once described the typical wildcatting process. Change the case taper and shoulder angle a bit, load the cartridge up until primer leaks / blown primers appeared and back charge off half a grain. Chronograph the result and then try and get Remchester to accept your new cartridge whose extra 250 fps came from the 29.75-deg angle shoulder or somesuch. As Mik M points out, shoulder angle efficiency nuts - proof house plus pressures the reason for super-high vels, everything.

But there have always been people who knew what they were doing and who ran stuff really hot - Newton and Weatherby to name two. The Weatherby Magnums are still loaded today to pressures that are at least the equal of any other production cartridges, and may be loaded higher still than anybody else's products - as they were for many, many years.

We have less excuse today than previous generations. We have such a range of powders and burning rates that we can optimise the load. It's no longer the situation where you had half a dozen IMR powders and if there wasn't one that suited the cartridge and bullet weight ideally, well that was hard luck and you had to decide if you were going to push things along a bit (too) high pressure with a too-fast number. We have top quality components and they're so consistent compared to one time, especially powders. People blew guns up simply by using a previously worked up hot load in one batch of powder and going straight into it with a new lot.

In a way, it's because of all our advantages that we push things now. If you worried a lot more about your invaluable smokepole that had cost a much higher chunk of your disposable income than is the norm now, not to mention chunks of hot steel and sprays of superheated molten brass in your face, you were likely a bit more cautious.

Maybe most of all, people didn't have chronographs, and they thought their handloads went a lot faster than they actually did, this all helped along by exaggerated MVs in manuals, overblown claims for factory ammo ballistics and so on.