THE HANDLOADING BENCH
308 Winchester Rides Again Part 4 By Laurie Holland
I’ve seen charge weights posted on American shooting forums that show charges running way above - 3-4gn sometimes - what would have been safe in my 2010/11 barrel. They are usually quoted for heavy-barrel tactical rifles from a particular American manufacturer with a reputation for being massively ‘over-throated’ and given ‘generous’ (slack!) chambers. Since my barrel was relatively short-throated, the loads quoted below should prove to be modest in rifles specially set up for these long projectiles but please, don’t assume anything here.
A chronograph is an invaluable aid in any load development programme but especially here as there is so much variation between barrels, chambers and the pressures/velocities produced. What sort of MVs should we be getting? Table 1 gives equivalent MVs to the Berger 155.5 at 3,000 fps, a good benchmark value in this exercise, so we hope to achieve around 2,600 fps with 210s in a 30 inch barrel.
With the substantially increased recoil from these bullets, I didn’t see any benefits in substituting them for 155-185gn loads unless I could achieve good groups allied to at least 2,550 fps MV, better still 2600. The load that gave the best combination of MV and group size in my barrel was the 208gn Hornady A-Max that produced MVs from just below 2600 fps up to 2625 fps depending on ambient temperature allied to small primer brass. But note that this was achieved using Reloder 17 and its unique ‘burning deterrent’ infusion throughout the powder kernels allied to Lapua ‘Palma Match’ small primer brass.
I wouldn’t expect to obtain these results safely with other powders or in standard large primer cases in that barrel. Conversely, I’ve seen shooters trying out heavy bullet loads in barrels that have been throated really ‘long’ for the Berger 210s who discovered on borrowing a chronograph that they were not getting high enough MVs from their loads, tight grouping combinations sometimes running under 2500 fps.
The results tables mostly speak for themselves, but I’ll make a few observations on them and the methodology. Test batches of 25 rounds were initially
loaded in eight by 3-round batches with charge weights deliberately starting low as this was new territory, especially in ‘Palma’ cases.
Promising combinations were run again fine- tuning weights around them in 5-round batches. I expected this rifle to put 155-185gn bullet 3-round combinations it liked into a single hole off the bench at 100 yards expanding to 0.25-0.35 inches with 5-round strings. Moving onto the ‘heavies’, 0.3 inch was a good result in 3-round strings and there were precious few sub-0.5 inch 5-round groups.
Where good groups were obtained, all too often it was at too low velocities to make the combination usable. Lateral stringing allied to a 2+1 / 4+1 pattern was the main problem (Figure 2).
Having had a few pressure problems with standard brass, I concentrated on the small primer ‘Palma’ variety with these bullets – I reckon this is the case form’s forte. On powder choice, IMR-4007ssc gave promising results but is too bulky producing heavily compressed loads at lower MVs than N550 or Re/E17.
H414 produced my best MV by a considerable margin but with undistinguished groups until the last (4-round) batch of a preliminary test, putting four 208gn A-Maxes into 0.4 inches at 2698 fps MV with a tiny 4 fps extreme velocity spread. Unfortunately, the barrel throat packed in shortly afterwards, so I didn’t manage to investigate further and see if this was one of these unrepeatable flukes occasionally experienced. The Hornady was the favoured bullet in my barrel and, whilst bullet-barrel compatibility is a very individual relationship, others I know who’ve tried this bullet like it too. (My new barrel from a different maker, True- Flite, seems to like the new 208gn Hornady HPBT a lot!) The Hornady projectiles, A-Max and HPBT are also cheaper than the Bergers, so I’d recommend giving them a try.
Overall, I reckon it’s much harder work to get the ‘heavies’ to perform well in 308 Win, you need to use Lapua Palma brass and their ‘pluses’ only give a real advantage in rough, changeable shooting conditions. They cost more, kick more and you wear your barrel out faster. If you want to keep life simple, specify my multi-purpose barrel throat and rifling form #1 to your gunsmith and stick to 155-190gn bullets.
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