New Peterson brass

[ebb]

I have no idea if it is true, but read years ago I think at Benchrest Centra. That any charge over 40 grains would work better with a LRP. And i hear some on here say they get better results with SRP magnum. I have no way of testing this but would love to know.

 

[Laurie]

I have no idea if it is true, but read years ago I think at Benchrest Centra. That any charge over 40 grains would work better with a LRP. And i hear some on here say they get better results with SRP magnum. I have no way of testing this but would love to know.

There was pages and pages of posts on this topic at the time of Lapua 'Palma' brass adoption on the Long Range Shooting Forums (the Palma teams' / discipline's main forum), and a lot of hard questions, opposition too.

The queries/opposition basically centred on two aspects:

minor one - doubts that small primer 308 was 'legal' under ICFRA regs. ('Unaltered 308 Win or 223') That was quickly put to bed in that SAAMI doesn't specify primer or flash-hole sizes for any cartridge, and the US team captains had cleared it with ICFRA anyway.

the main objection - it wouldn't work. This went back to the early days of the Remington BR cartridges when Big Green (or anybody else) didn't make 6, 7, 30 or any other calibre BR brass, rather a thin-walled, small primer / flash-hole 308 Win case for reforming. Sometimes referred to as UBBR - Unformed Basic BR. Naturally, more than a few people tried these cases as made, straight from the box in 308 Win form attracted by their greater powder capacity than standard 308 Win because of the thin case walls, and the promise of more consistent ignition. A lot of these people also ran into ignition problems, it apparently being marginal. Some experimenters drilled the flash-holes out to the standard 0.079" diameter or thereabouts and partly or completely solved the problem, but this rather defeated the object of the exercise and experiments on the BRs and PPCs had shown that ES/SD rose if the hole exceeded 0.070" diameter.

There are many on this forum who can talk from direct experience about this brass and experiments / problems with it in those days. (The cases are still remarkably common in the US even now, many years after their limited production ended.)

Anyway the SDP 308 Win concept was abandoned back in the 70s, 80s, whenever exactly this was, as one of these good ideas in theory that simply didn't work in practice. Then a highly successful US Palma shooter whose name I can never remember - but I know will be supplied here by at least one AS Forum member - retried the Rem UBBR cases some years later using original Rem examples, and got superb results. He convinced his fellow Palma team members to look at the concept again and in turn their captains persuaded Lapua to make a few thousand trial SP 308 cases. ......... and the 'Palma' case was born and put on general sale, albeit with some caveats such as not to be used in cold weather.

The fact that 90 odd percent plus of FTR shooters use this type of brass, loading primarily Hodgdon / ADI extruded grades in the US and on my side of the Atlantic Viht N150 in 44-47gn charges tells you that it works with 40gn or higher charges with at least some popular powders. It also works from my own experience with some ball-types, but not all (eg disastrous results with Hodgdon / St. Marks CFE-223). I have sat alongside former national champion and world class FTR competitors working loads up or testing new powder lots, and I have no doubts (my own personal experiences aside) about the tiny groups they shoot and the small MV variations they see.

Here's the final part of a trio of articles on small rifle primers with the test results on a 45.5gn Viht N150 powder charge from some 15 primers models. I don't see any sign of ignition problems! (However, I had poor results previously in cold conditions - mid 30s F - with its stablemate N140 which appears to prefer an LR primer whilst N150 had also performed superbly on the same day in the same temperatures - go figure!)

http://www.targetshooter.co.uk/?p=2662

The 'magnum' SP primer issue is much more about primer cup thickness and strength rather than primer brisance.

My personal opinion is the type is 'marginal' for 308 Win size cases / charges and those of similarly dimensioned cartridges, so it's no panacea and some users end up unhappy with them. It's a case of suck it and see in the particular application and with different primers / powders. The easy, simple option is to buy large primer brass when there is a choice, and for field use ('hunting'), I'd advise large primer every time.

The other factor is that the SP versions of 0.473" dia head cases are much stronger / tougher than their conventional large primer brethren. In the UK - can't comment on US practice - SP 6 and 6.5mm Creedmoor Lapua brass is used by many top competitors in Tactical type comps with some impressive MVs from heavy bullets, no doubt with some 'impressive' (read scary) chamber pressures to match. But boy, do these things perform often holding their own with out & out F-Class rifles at up to 800 yards.

 

[ebb]

Yea to the best of my understanding it's always been about withstanding higher pressure. I am kinda jaded I had a big magnum rifle that the smith put together in a hurry, and it had too short of a firing pin and hangfires were the death of it. I tried standard LRP primers in it and it was unshootable then went to magnums and it got a little better, Greg Tannel fixed the firing pin and Col Billy put a new barrel on it and its 100% now.

 

[JB10]

The only two srp i compawas rem 7 1/2 and fed 205. The fed 205 were 30 fps slower than the Remington in a 223. Now in my 308 i have used lrp and srp Both were Lapua brass. They were exact same powder charges and bullet. The srp palma brass loads shot slower and were low right from the lrp loads. I dont remember how much slower they were

 

[Steve Donlon]

SRP ignition gives very different results from LRP in this size of case, powder charge type and weight. This is a normal expectation among 308 Win Lapua Palma SRP brass users for instance and charges are adjusted upwards almost as a matter of course.

Far from 50 fps being an abnormal reduction, it's pretty common in this size of cartridge, and I've seen larger MV reductions in some comparisons. SRP charges usually have to be adjusted up by 0.5 to 1.5gn on an LRP to SRP switch in Creedmoor / 308 Win size cases depending on charge weights and the powder burn-rate and/or how easily it ignites.

The cause is that SR primers are far less aggressive than LR equivalents and the volumes / weights of super-heated gas and solid ejecta that they force into the powder column is much reduced. If ambient temperatures are low and the case-body brass and powder kernels cold, they have much less energy available to heat those items up and reach the temperatures that give consistent ignition. That's why Lapua advises against this type of brass in cold weather hunting. If your testing was done in anywhere close to freezing point never mind below, this may also have affected your results. Lapua and Peterson SRP cases also come with smaller diameter flash-holes than LRP equivalents - 1.5mm vs 2mm - and this affects ignition too. (It improves consistency reducing MV spreads where it works well, but can make a poorer job of igniting the powder column in non-optimal situations.) Finally, SRP ignition doesn't work at all well with some powders. I couldn't get it to work in 308 with Hodgdon CFE-223 for instance - two complete misfires and almost every other round a mild hangfire.

As an example of MV reduction, have a look at:

http://www.targetshooter.co.uk/?p=2621

at a table at the very end of the piece on 308 Win / 167gn Scenar / Viht N150 LRP and SRP MVs fired side by side in a single session, both in Lapua brass with very close fireformed water capacities.

The final point to note is that not only does SRP brass require heavier charges, but it has very strong case-heads due to the primer pocket being smaller and removing less metal from a key pressure-bearing area of the case. As a result a full-pressure charge worked up in an SRP case should never be transferred as is to LRP cases even of the same make. It is essential to drop charges and work up again.

Thanks for clearing this up for all of us. I was shooting Lapua LRP 6.5 Creedmoor brass using 40.5 grs. of IMR 4350, very accurate at 500 yards using 9 moa. Then I shot my Lapua SRP brass using 41.5 grs. of IMR 4350 and I needed the same 9 moa to hit center. I thought I was loosing my mind, could not figure it out I did not think there could be that much of a difference with no difference. Any thoughts on Starline 6.5 Creedmoor SRP brass with the large flash holes and this dilemma with IMR 4350 powder?

 

[Ryan66]

Thanks for clearing this up for all of us. I was shooting Lapua LRP 6.5 Creedmoor brass using 40.5 grs. of IMR 4350, very accurate at 500 yards using 9 moa. Then I shot my Lapua SRP brass using 41.5 grs. of IMR 4350 and I needed the same 9 moa to hit center. I thought I was loosing my mind, could not figure it out I did not think there could be that much of a difference with no difference. Any thoughts on Starline 6.5 Creedmoor SRP brass with the large flash holes and this dilemma with IMR 4350 powder?

Steve I use starline srp 6.5 creed brass with cci450’s but with 41.3gr of H4350 under a 140 bullet. I’ve shot it in temps from 20’s to 90’s and not had ignition issues nor any negative shifts of SD/ES in the colder temps. I don’t have extensive data and would have to dig through journals to find all the cold weather info .. my fingers get cold when it’s only 20 so I don’t tend to shoot much when it’s like that

Maybe I’m just lucky though. I’m not sure how IMR4350 might react compared to H4350 though - the hodgdon version is notoriously good at temp insensitivity.

 

[6.5 forever]

Steve I use starline srp 6.5 creed brass with cci450’s but with 41.3gr of H4350 under a 140 bullet. I’ve shot it in temps from 20’s to 90’s and not had ignition issues nor any negative shifts of SD/ES in the colder temps. I don’t have extensive data and would have to dig through journals to find all the cold weather info .. my fingers get cold when it’s only 20 so I don’t tend to shoot much when it’s like that

Maybe I’m just lucky though. I’m not sure how IMR4350 might react compared to H4350 though - the hodgdon version is notoriously good at temp insensitivity.

My experience is almost exactly the same

 

[Steve Donlon]

The only two srp i compawas rem 7 1/2 and fed 205. The fed 205 were 30 fps slower than the Remington in a 223. Now in my 308 i have used lrp and srp Both were Lapua brass. They were exact same powder charges and bullet. The srp palma brass loads shot slower and were low right from the lrp loads. I dont remember how much slower they were

I had the same outcome taking Lapua SRP brass and opening up the flash hole and the bigger flash hole moved the bullet up higher to the left. I'm going to try the Starline SRP brass with the large flash hole. See no reason for such a small flash hole. Maybe it is all about the powder. I'd like to know which powders like the smaller flash hole because I see not enough benefits with it. Even using RL16 powder ,the larger flash hole shot better in my rifle. But it's a 3 groove Pac-Nor and shows pressure sooner than a 5 groove from what I've seen.

 

[Laurie]

Thanks for clearing this up for all of us. I was shooting Lapua LRP 6.5 Creedmoor brass using 40.5 grs. of IMR 4350, very accurate at 500 yards using 9 moa. Then I shot my Lapua SRP brass using 41.5 grs. of IMR 4350 and I needed the same 9 moa to hit center. I thought I was loosing my mind, could not figure it out I did not think there could be that much of a difference with no difference. Any thoughts on Starline 6.5 Creedmoor SRP brass with the large flash holes and this dilemma with IMR 4350 powder?

In small precision SRP only cartridges with small flash-holes as part of the mix - PPC, BR and suchlike - experiments have shown reduced precision and larger MV SD values when flash-holes are opened to ca. 70 thou' or larger.

This may or may not apply to larger cartridges of the Creedmoor, 308 Win size. It may also depend on both primer make/model and powder grade. Starline says that when it decided to offer the SRP option on some rifle cases, it tested prototypes with both size flash-holes and obtained better results with the standard 2mm (0.079-inch) dia. version which it subsequently adopted. I know one or two people who use this brass either in the original or reformed to something else and they're happy enough. My sole look at a Starline SRP case has been a one-off with a 308 Win Norma 202 load where I got better results from LRP Lapua brass, but there are so many variables here, that this tells us virtually nothing. No doubt about it, SRP / small flash-hole brass in 308 Win size cases see marginally efficient ignition resulting in marked powder preferences, so with some powders Starline may very well be correct, or it may be better still to stick with traditional LRP.

 

[Straightshooter1]

In small precision SRP only cartridges with small flash-holes as part of the mix - PPC, BR and suchlike - experiments have shown reduced precision and larger MV SD values when flash-holes are opened to ca. 70 thou' or larger.

This may or may not apply to larger cartridges of the Creedmoor, 308 Win size. It may also depend on both primer make/model and powder grade. Starline says that when it decided to offer the SRP option on some rifle cases, it tested prototypes with both size flash-holes and obtained better results with the standard 2mm (0.079-inch) dia. version which it subsequently adopted. I know one or two people who use this brass either in the original or reformed to something else and they're happy enough. My sole look at a Starline SRP case has been a one-off with a 308 Win Norma 202 load where I got better results from LRP Lapua brass, but there are so many variables here, that this tells us virtually nothing. No doubt about it, SRP / small flash-hole brass in 308 Win size cases see marginally efficient ignition resulting in marked powder preferences, so with some powders Starline may very well be correct, or it may be better still to stick with traditional LRP.

Apparently, Alpha Munitions has done some testing too and why they've gone with a larger flash hole for their SRP's.

Switch Or Stay | Alpha Munitions

alphamunitions.com

 

[Laurie]

Apparently, Alpha Munitions has done some testing too and why they've gone with a larger flash hole for their SRP's.

Switch Or Stay | Alpha Munitions

alphamunitions.com

Yes, I've noticed that. It seems that Hornady, Starline, Alpha and PPU have for whatever reasons decided to retain 2mm flash-holes in their SRP brass. Lapua and Peterson have adopted the small version with their SRP 'special option' variants. (I'm assuming that the promised Lapua 6GT brass will have 1.5mm flash-holes as with their existing 308 'Palma', 6.5X47L, and Creedmoor SRP cases.)

As always, you pays your money and makes your choice!