THE HANDLOADING BENCH
308 Winchester Rides Again Part 2 By Laurie Holland
THE HANDLOADING BENCH 308 Winchester Rides Again By Laurie Holland - Part 2
I’ll look at Lapua’s 308 Win ‘Palma’ match case this month, exploring its raison d’être, wondering whether it’s worth the extra money over the common or garden large primer model (£79.73 v £56.96 per 100 recommended retail prices).
But first, for those of you unsure of what Palma brass is, here’s a description and potted history. Dimensionally, the Palma case is identical to the company’s standard version. By that, I mean both not only conform to CIP/SAAMI dimensions but have near identical wall and neck thickness values and will have the same internal capacities after fire-forming in any given rifle chamber.
Any differences here are only what you might find between production lots. This suggests both cases start with the same materials and are drawn and formed in the same dies on Lapua’s production line. The differences are found in the ignition department, the standard model using the Large Rifle primer (LRP) and 2mm (0.080”) diameter flash-hole; the Palma version given a smaller diameter pocket for the Small Rifle primer (SRP) allied to a 1.5mm (0.059”) flash- hole. This combination puts the case into an elite group comprising the .220 Russian/PPCs, BRs and 6.5X47mm Lapua, other SRP users such as .223 Rem having the standard 2mm dia. aperture.
The 308W ‘Palma’ case is a specialist target shooting item, its makers advising it should not be used for loading ‘hunting’ rounds – I’ll come to the reason for that later.
Why change the tried and trusted 308Win format, one that has given excellent service for six decades? The objective is not enhanced accuracy (‘precision’) per se as in the smaller cased numbers such as the PPC and BRs with their 28-32gn charges, rather to reduce the spread of muzzle velocities by reducing primer energy close to the minimum level that reliably ignites 42-49 grain weight powder charges when the cartridge is used in ‘reasonable’ ambient temperatures.
In the past, dedicated long-range 308 competitors assiduously sought out particularly ‘mild’ batches of favoured LR primer brands, usually RWS and more recently the Russian manufactured PMC/Wolf/Tula models.
MV variations start to become important when any cartridge is used in long-range precision shooting but can affect some 308W loads particularly badly as the cartridge is pushed to its ballistic limits at 1000 yards and beyond. To be precise, such variations can induce ‘poor elevations’ on the target.
Also, if the bullets’ terminal velocities are close to a ballistics boundary of any sort, dropping through or sometimes even approaching the sound barrier being the most important, a large MV spread causes all sorts of unpredictable behaviours in some bullets. Wind changes can have disproportionate effects in such situations for instance. This may be one cause of the oft-heard complaint from long-range tyros that their rifles and ammunition group really well to 800 yards, but shoot all over the target at longer ranges.
‘Palma’ Connection
‘Palma’ refers both to a legendary shooting trophy and a long-range prone discipline using iron-sighted fullbore Target Rifles. The former was inaugurated in a five-nation team match shot on the long-gone
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