I covered this brass in Target Shooter Online February to April issues under the title of ".308 Winchester Rides Again", looking specifically at the Palma case and moving onto heavy (over 190gn) bullets in both standard and small primer brass.
The 3 issues are available to view or download free on
http://www.targetshooteronline.com/
as Adobe pdf files.
My findings were that with lighter bullets, some powders didn't like the small primer brass over much. In others, it did as well as standard large primer brass and in some but not all combinations, it did what is claimed - provide a reduction in velocity spreads in a majority of charge weights when working up over 2-3gn overall ranges.
It IS very affected by low temperatures with some - but not all - powders. Low is defined roughly as somewhere around 5-deg C and below, but the boundary may be higher with some powders. Viht N150, which gives very small ES values in standard brass anyway was unaffected by 2-3 deg C temperatures in Palma brass and gave very similar results to the same loads in standard brass, but Viht N140 in standard (stiff) loads under a 155 gave much poorer results than the same loads in large primer cases shot alongside. Redoing the Palma / N140 test in warmer conditions saw a large rise in MVs and huge performance improvement in terms of group size and ES values.
A standard feature is that the Palma case will normally give a slightly lower MV with any given combination, compensated for by increasing charge weight a little.
Some unexpected results appeared, e.g. the Palma brass did better than standard LRP cases with 'hard to ignite' Hodgdon spherical H414 under a heavy bullet.
I deliberately didn't load any 155 SMK / H. VarGet combinations. If the US Palma Teams say this combination works at 800-1,000yd, I for one believe them and won't reinvent any wheels.
So far, not so pretty ...... BUT
Palma brass is
THE brass for heavy loads under heavy bullets (200gn and up) and slow burning double-base powders. That is Viht N550 and Alliant Reloder 17. It works well, you can safely get higher MVs than with standard LRP cases, and the brass takes what should be one helluva hammering without excessive case-head and primer pocket expansion. All but one top GB F/TR shooters who have switched to 210s and up use these cases and despite having employed
very stiff loads still have tight primer pockets after 10 or more loadings / firings.
So in summary, if you're shooting standard velocity loads with 155-185gn bullets, I see little or no benefit in using them with the possible exception of 155 / VarGet.
If temperatures are low avoid them.
If you want to push 210s out at 2,550 to 2,700 fps from a 30" barrel, you should definitely give them a try alongside N550 and Re17.
In my side by side tests, I used F210M primers in standard LRP cases and CCI-BR4 in Palma cases.
