THE HANDLOADING BENCH
308 Winchester Rides Again Part 2 By Laurie Holland
by side comparison and also see what sort of 100yd groups could be obtained. The 185gn Berger/N550 combination compared 15 rounds of existing LRP ammunition left over from the 2010 F Class season against three freshly loaded batches of five rounds with rising charge weights in SRP ‘Palma’ brass. CCI- BR4 primers were used in the ‘Palma’ loads, Federal 210M match primers in the three LRP control groups.
Cratering and piercing SRPs at high but not excessive pressures is an endemic problem in some rifle actions. These examples are from .223 Rem cartridges fired in an AR-15 type rifle.
Since we got our first ‘Palma’ cases as winter approached, I was keen to try them out in cold weather ... well, cold by UK standards. My initial efforts with the new brass employed three Vihtavuori based combinations that I knew worked well in all seasons with LRP cases: the near standard TR clubman’s load of 155gn Lapua Scenar over a stiff charge of N140; 175gn Sierra MK over a mild load of stable and easily ignited N150; my then favourite long-range F/TR combination of the 185gn Berger BTLR and N550.
As I expected pressures and MVs to be a bit lower than normal due to the SRP effect on its own, a range of charge weights was used in each of the trio. The N140 and N150 combinations were also loaded in standard Lapua LRP brass, the two lots shot fully supported off a bench rest in a single session to allow a side
The two 175gn SMK/Viht N150 variants were the first to be tried in my initial range session held on 18th November 2010. My notes describe the conditions as cold (3-4°C) with a moderate crosswind from the right. Five by 5-round batches whose charge weights rose from 42.0-44.0gn in 0.5gn steps had been loaded the day before in the two types of Lapua case. The 10 groups ranged from 0.4 to 0.7” centre to centre averaging around the half-inch mark with no difference at all attributable to case type. MVs and MV spreads were very much as expected, the ‘Palma’ versions losing some velocity, but sometimes producing reduced ES values. So far so good, especially as N150 usually produces small velocity spreads in LRP form. In fact, I’d normally expect better results than I got here with high single figure values up
The Barnard Model ‘P’ bolt and striker assembly. The small diameter firing pin is a close fit in its bolt-face aperture and won’t see any problem with high pressure loads using SR Magnum or BR primers.
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