The advice to use SR magnums in the small-primer version of this cartridge is correct. It has nothing to do with SRM primer 'strength' (brisance), rather cup strength from thicker metal. Standard SR primers (CCI-400; Rem 6 1/2; PMC/Murom KVB-223; Winchester WSR) are VERY prone to 'crater', worse 'blank' (fail in the firing pin indentation allowing gas escape) in many factory rifles. Tikkas appear to be very well made and this may or may not be an issue with them.
This is an evergreen topic on this and other forums, and there is one currently (barely) live one on SD:
Remington 700pps 308 Match Ammo Recommendations
Unlike SR standards vs magnums, LR Magnum primers are often very different from their standard counterparts with much more aggressive charges that raise pressures. Unlike their SR brethren, there is no cup inherent strength difference, all makes and models specified at 27 thou' thick brass. In cartridges such as 308 Win, 7mm-08, 6.5 Creedmoor, LRs can sometimes give as good or better results even in range use, and the LR version should be used for cold-weather stalking and with some hard to ignite powders. The SR primed big plus for many long-range competitors is that with less metal removed for the primer pocket from the case-head, cases are MUCH stronger allowing continuous use of heavy loads. 308 Win Lapua 'Palma' SR primed brass sees indefinite use of heavy competition loads that would stretch case-heads/ produce slack primer pockets in four or five firings with LR brass from the same maker.