What does small-primer 308 brass do for me?

[fivering1]

The only real benefits are more reliable ignition in colder temperatures and potentially longer brass life in regards to primer pockets. If you bump your shoulders too much, the cases will still separate.

Sorry, but for more reliable ignition in colder Temps you need to use a LR primer, preferably a Large Rifle Magnum Primer.
If you will bump your case shoulders back only about 1 to 1-1/2 thousandths they will be usable for a great many reloads.

 

[Laurie]

Running a load with 185s that was predicted to be at ~61K psi (QuickLoad) in Standard .308 brass gave me around 4 to 6 firings. In SRP Palma brass, I can't even tell you the average number of firings that same load would give, because I haven't gotten there yet, but it's at least 12 to 15, or more. The increased case head thickness and extra metal around the primer pocket makes Palma brass far more resistant to the [relatively] high pressures we often run in F-TR loads.

Pre-Palma brass, many F/TR competitors I used to shoot with routinely ditched expensive (and prepped) Lapua cases at ~5 firings, some people with particularly hot Berger 210gn Loads after three firings. Nobody annealed cases as expanded case-heads as the case-heads expanded before shoulders / necks showed problems. Come Lapua 'Palma' cases and with annealing case-life is at the 20 firings mark for some people I know, and loads are hotter / MVs higher than they were pre-Palma.

Viht N150 is very widely used with 185s and heavier in the UK. This powder gives no ignition issues down to freezing point with the Fed 205M, CCI-450, CCI-BR4. (Although we shoot in the open 12 months per year here, daytime temperatures below 0-deg C / 32 F are uncommon, but just above isn't unusual in winter.) I have seen other powders start to produce problems below 4 or 5-deg C , ie in the 30s F.

So far as ball powders go, I've had completely opposite results with two Hodgdon / Gen Dynamics St. Marks powders in 308 SP brass. In my initial winter testing at just over freezing when Lapua first produced 'Palma' cases, against control large primer Lapua brass, the longstanding Hodgdon H414 (same thing as W760) performed very well indeed - in fact outperformed the large primer case much to my surprise. When CFE-223 appeared, results were reasonable to good plus very high MVs in large primer cases, but terrible in SP brass - large ES values, sudden and large increases in MVs when working charges up, hangfires and in 50 rounds two complete misfires. The ambient temperature was ~15-deg C (59 F), so this shouldn't have been a factor.

I don't think anybody has mentioned charges / MVs yet. In 308 size cases / charges, SP MVs are lower than with the same make / capacity LP standard examples. The original testing done with prototype cases around 10, 12 years ago by the US Palma Teams with their 155gn SMK (2156 version) over something in the low 40s VarGet needed 0.5 to 0.6gn heavier powder charges to bring the SP MVs back up to the original. Depending on cartridge and powder, I've seen the difference run at as much as 1.5gn, even 1.7gn (N150 in 308 Win with the 167gn Lapua Scenar).

The many 6.5mm Creedmoor users here in the UK who adopted the SP-only Lapua case when it appeared a couple of years ago seem to have mixed results ranging from superb down to hangfires appearing with some powders at anything much below 10-deg C / 50F. Lapua is now producing a large primer version alongside the original 'for hunters', but I suspect also in reaction to complaints from target shooters too. In my brief early days foray with the Creedmoor, only LP brass was available, so I never worked up any SP loads. (Right from day one though, early British Creedmoor adopters were necking 308 Palma brass down, and I reckon that they're running 147gn ELDs around 100 fps faster than they could with the best of the LP brass, and yet more than Hornady would take.)

 

[BW64]

You know what they say, "smaller is tighter".

I can vouch for this!!

BW

 

[Dave Marshall]

Sorry, but for more reliable ignition in colder Temps you need to use a LR primer, preferably a Large Rifle Magnum Primer.
If you will bump your case shoulders back only about 1 to 1-1/2 thousandths they will be usable for a great many reloads.

You are correct, I wrote that completely wrong, lol.

Edited to be more correct.

 

[corning]

I dunno. I do know I used to shoot SRP 308s at 600 (Remington BR Basics) with a 190 and 42,2 4064 that gave me 14x at 600 one day (iron sights) , shot like lasers they did.

As always YMMV.

And I have shot some phenomenal scores with the large rifle primers. So yes, YMMV.

 

[dbduff]

If your rifle is chambered with plenty of freebore, let's say at least 0.125" to 0.150" for a Berger 185 Juggernaut or 0.170" to 0.180" for a 200.20X bullet, you will likely be running pressures of around 59K psi to just under 62K psi to hit the commonly-used accuracy nodes that F-TR shooters often run (~2720-2740 fps for 185s over Varget from a 30" barrel, ~2640-2660 fps for 200.20Xs). Even though SAAMI MAX pressure for the .308 Win is 62K, the primer pockets in Standard .308 brass (LRP) will not last as long at those pressures as the SRP pockets in Palma brass. Running a load with 185s that was predicted to be at ~61K psi (QuickLoad) in Standard .308 brass gave me around 4 to 6 firings. In SRP Palma brass, I can't even tell you the average number of firings that same load would give, because I haven't gotten there yet, but it's at least 12 to 15, or more. The increased case head thickness and extra metal around the primer pocket makes Palma brass far more resistant to the [relatively] high pressures we often run in F-TR loads.

I have used Palma brass for several years now and wouldn't even think about switching back. I regularly practice during the winter season when ambient temps are between 30 to 40 degrees, using loads with 185s, 200.20Xs, and 215s over Varget with Fed 205 primers, and I have yet to experience any ignition issues. I suspect that ignition with small rifle primers and Varget loads is more likely to be an issue when ambient temps get below the upper teens to mid-20s, rather than in the 30s to 40s. Of course, that may change depending on your chosen powder and the brisance of the the primer you're using.

 

[dbduff]

Never seen the term brisance capability before on this forum. Had to look it up!
D

 

[Liven The Dream]

Ned said it all .
Long time Palma Shooter now F/Class Old Guy .
I made the switch to Peterson SP .308 with 185's getting to that 2800 + with LP was hard on Brass.
Try it you will be Happy

 

[XTR]

Never seen the term brisance capability before on this forum. Had to look it up!
D

I've learned all kinds of terms in this reloading game, like "obturate", never heard the term till I loaded for BPCRs.

 

[Lefty Trigger]

I see it as basically an answer to a non-existent problem

Like small primer 45ACP brass...

 

[dgeesaman]

The theory goes that small primers give less violent ignition and therefore less deviation in shot to shot velocities. These translate into smaller vertical dispersion at 800 to 1000. I dunno.

At least in theory, the hand loader can control powder charge with a top quality balance scale and handling powder by lots.

Variations in the primers themselves are less obvious and sorting by weight is not ideal because you won’t know if the variations are metal vs primer charge. Some shooters have found it helpful, but that’s another subject.

Having more of propellant come from powder theoretically gives us more quality control. Assuming you have good fill density and enough brisance for consistent ignition.

 

[riflewoman]

Ned said it all .
Long time Palma Shooter now F/Class Old Guy .
I made the switch to Peterson SP .308 with 185's getting to that 2800 + with LP was hard on Brass.
Try it you will be Happy

your load is still hard on the brass, just less obviously so.

 

[Liven The Dream]

your load is still hard on the brass, just less obviously so.

Me and a few other people, I do have a pit of a throat in that barrel also .

 

[Turbulent Turtle]

Never seen the term brisance capability before on this forum. Had to look it up!
D

Yeah, it comes from the French word "briser" (to break), not to be confused with "baiser", which has a totally different meaning.

(Where is that ducking-for-cover emoji?)

 

[BradY]

I have seen issues with SRP brass FGMM primers and 155gr bullets and very cold temps. You CAN get magnum primers that fit SRP brass. I wouldn’t run anything heavier than a 185gr bullet in LRP brass but I’ve seen 200’s shoot well at low 2600’s not sure how long the brass was lasting though.

 

[Nature Boy]

I wouldn’t run anything heavier than a 185gr bullet in LRP brass

Even 185s loaded to F Class levels will last only 4-5 cycles before the pockets get too loose. That’s why I switched to SRP palma brass last year

 

[500yards]

Although I cannot share my thoughts on your bushing situation I will utter what Lapua believes about the primer situation. They claim that the initial ignition of a cartridge should be as mild as possible and still get everything done (i.e. Full ignition of the cartridge). They believe that a smaller primer ignition is less intrusive and disturbing to the system allowing everything else to have more accuracy potential. Is this true? No idea. I've used all kinds of their stuff. What I do know to be true is that if you have a small hole in the same material as a larger hole. The smaller hole will be stronger and the material last longer and take more abuse. That I can put a stamp of "I've witnessed this" for you. So. In my eyes it's worth a try. Accuracy. Not sure. Longevity absolutely.

 

[Laurie]

They claim that the initial ignition of a cartridge should be as mild as possible and still get everything done (i.e. Full ignition of the cartridge). They believe that a smaller primer ignition is less intrusive and disturbing to the system allowing everything else to have more accuracy potential. Is this true?

As a general guide, yes and it far predates the use of small primers in 308 Win cartridges. For many years, some 'milder' models of Large Rifle primers were preferred for use in Palma Rifle in 308 Win for example. Equally, known 'hot' models were avoided as they increased ES values. Some production lots of the German RWS standard primer were highly sought-after for being in the best of first type and the Remington 9 1/2 has long been regarded as falling within the latter group. As a longstanding Palma competitor, I'm sure that @riflewoman can add something to this comment.

None of this is particularly new or groundbreaking - primer flash photography written up years and years ago by German Salazar and others conclusively proved correlations between less energetic / smaller ejecta cone primer models and reduced ESs in cartridges like the 30-06.

Adopting the SP primer form is therefore nothing new in intellectual terms, rather simply taking the concept forward in a different way and gaining a stronger case-head as a side-benefit. Where it becomes controversial is whether it takes the concept too far - ie whether the primer now generates insufficient energy for the task under some (or in the views of some shooters all) conditions.

Incidentally, there are a few examples of where smaller size cartridges offer a choice. Typical of military cartridges the Soviet M43 7.62X39mm cartridge is large rifle primed - much more than needed for this size of case and 20-odd grains charge, but absolutely guarantees ignition in Arctic warfare and similar abnormally adverse conditions. The first change to making this number a precision cartridge was the adoption of the SP primer and 1.5mm dia. flash-hole when 7.62X39 morphed into the 220 Russian (and later the PPCs). That was ground zero for the SP / small flash-hole concept and everything subsequent started there. (Having said that, cartridge designers and early US bench rest competitors have experimented with flash-tubes and other sorts of novel ignition concepts recognising the relationship between ignition characteristics and precision.)

Returning to the humble 7.62X39mm M43, most commercial cases are also LP, but Remington made some 'Peters' headstamp in SP form. (I always wondered why as the company also made LP cases under the Rem or R-P headstamps.) I never did manage to get around to testing the two forms side by side for this one. I did manage though with 6.8mm Rem SPC where Remington brass is LP and Hornady SP. To my surprise, the chronograph came up with no significant difference between them in either average MV or ES size. What does show up though is that the large pocket in the Rem variety weakens this cartridge's small diameter case-head severely so warm loads will expand it quickly. This (rather than ignition characteristics per se) is no doubt why Hornady chose SP. The same issue has since arisen with the 7.62X39 sired 6.5mm Grendel. Lapua uses small primer / small flash-hole and the PPU version initially used the large size in both. PPU soon acquired a reputation for 'weak' shortlived brass among Grendel fans, no doubt again down to the large hole in the small case-head scenario, so the company has now switched to the small primer form in this cartridge.

That raises another issue. Whilst most small SP using cartridges stick with the standard 2mm (0.079") dia. flash-hole (222/223, 6.8 SPC etc) those designed 'in a precision mode' starting with the 220 Russian, working through Rem and Norma BRs up to the 6.5X47mm Lapua design and now SP 'precision' variants of traditionally LP designs such as 260 Rem, 308 Win and suchlike have all also adopted the 1.5mm flash-hole which has a major ignition effect in itself. Many experiments involving reaming out these flash-holes in steps have shown changed ignition behaviours, usually not for the better. In 6mm BR, it has long been recognised that the tipping point is around 0.070" - hit or exceed that size and MV, ES, and groups all grow. Some of the new SP brass - eg the PPU SP version of 6.5 Grendel - retain the larger 2mm / 0.079" flash-hole - and therefore likely behave differently from versions with both characteristics in situ. Whilst many of the new SP 'precision' variants of traditional LP cartridges - 243, 260, Creedmoors, 308 Win - from companies like Peterson are SP/SF-H, other producers have retained the larger diameter flash-hole. This will certainly improve ignition reliability in marginal conditions, but may also increase ES/SD values. I have both SP PPU and Lapua Grendel brass now and will compare these aspects, but one would expect Lapua's inherent quality / consistency in other aspects to be better. (Lapua is shall we say just a touch - ha! ha! - better in weight and neck thickness variations on initial examination and could be in others too that are less obvious.)

So for buyers of unprimed brass, there are now three not two variants available likely to each produce a different result. The other factor that worries me a lot and which as far as I can see has been barely mentioned, never mind given any prominence, is the potentially dangerous effects of switching from a really hot load in SP brass to the LP case form, especially with a particularly hot Large Rifle primer, the aforementioned Rem 9 1/2 and some of the LR Magnums like the Federal 215/215M. A combination of increased pressure through ignition change and a significantly weaker case-head ............ !! Yes, I know the standard advice of change anything and drop charges / work up, but as with the small print in reloading manuals that say 'these loads apply only to the listed makes of components', how many people actually heed such warnings? This really could be a case (pun!) of caveat emptor!

 

[riflewoman]

While I never made any team, I did like to shoot Palma and I excelled at the 600 stage of the NMC. So that said, I do recall having a jaw-Jack session at Camp Pendleton with a couple of Palma team members about primer selection. One even related how he made up a special rifle to shoot BBs over a chronograph using primers only to select “the best lots” of primers. The criteria was a low velocity and a low ES of these BBs. These lots would then be loaded and shot. As often as not, these selected lots were relegated to “600 yards” rather than Palma ammo. So even at that there’s no telling.

That was about the time I tried small primers and found that my X count did go up, so there seems to be some merit in shooting small primers at distance. But with the difficulty of reliable ignition in a 308 sized case it isn’t a panacea.

I have some of the Remington SRP 7.62x39 brass which I’m going to reform into 6mm Grendel. I also still have some old “PALMA 308 WIN” brass made by Winchester. Large primer but a cavernous capacity.

 

[Laurie]

One even related how he made up a special rifle to shoot BBs over a chronograph using primers only to select “the best lots” of primers.

Oooh I do love that - now that's REAL dedication!

I hadn't heard that one, but remember reading a long time ago probably in Precision Shooting Magazine of a top US sling shooter who had found European Berdan prime brass with the twin small flash-holes worked better than any Boxer primed load at long-distances. He got somebody to import bulk lots of primed Austrian commercial Hirtenberger 308 Win Berdan cases for him and junked them after a single firing.