Hi Sheep1
There are variables for small primers and case capacity most prominent is temperature 08 palma brass reports are 50gn is max, before you run into ignition problems.
remington started small primer 308win cases decades ago.
point of fact i have shot 1,000s of rounds with 51gn of powder with fed 205m in the 308 win case during spring summer and fall 5oC and warmer
below 0 i have tested 47gn without miss or hang fires.
46gn in a 6.5 creedmore should be no problem provided you are not hunting with it at temps below -5... i have not tested small rifle and my charge weights below -5
i was abler to find this post by Laurie (UK) discussing concerns about case capacity and small rifle primers
Some years back when prototype 308 Lapua brass was being trialled, the issue was extensively reported on and discussed in the Palma teams long range forum:
http://forum.accurateshooter.com/threads/primers-small-vs-large-fact-vs-theory.3906793/
Many of the 'old BR and fullbore hands' came out of the woodwork saying they didn't care what the team captains said, but they knew that small primer / small flash-hole brass simply doesn't work consistently and reliably in the 308 Win through their own past experiences.
This was with the old very thin-wall / high capacity Remington UBBR (Unformed Basic BR) cases. For those who've never heard of this, it goes back to the dawn of the 6mm and other calibre BR cartridges, the genre starting out as a reformed 308 case, the Barnes .308X1.5" prototype short assault rifle military number. Remington developed the BR, produced chamber and reamer specs, but didn't sell ammunition or cases for 20 plus years, instead making some lots of the thin-walled UBBR brass for would-be BR shooters to reform to whichever version they desired.
As well as becoming the raw material for goodness knows how many other wildcats, many American rifle competitors thought to themselves - hey let's leave it as 308 Win, it's high quality, got a high capacity = scope for increased charges and MVs within acceptable pressures, and it's small primer which = improved precision / smaller spreads.
Now these guys almost without exception said it didn't work, or at any rate not consistently enough, basically because the small primer is inadequate for 45+ gn charges of medium burning speed powders. Some reported that drilling out the flash-holes as per savagedasher above effected a partial or complete cure. All said the resulting rounds became overly temperature sensitive, in this case low temperatures the issue.
So, that was the observed experience of a lot of experienced and knowledgeable guys 30, maybe 40 years ago, call it 'anecdotal' or 'experimental' according to views and taste, and these survivors of that era were adamant that Lapua and their national Palma team were on a hiding to nothing. Experience has show the complete reverse with Palma brass a great success story with only marginal downsides that can be lived with. So, either this was inaccurate / plain wrong anecdotal stuff, or (in my view more likely) evidence that something has changed between the 1970s/80s and the 20-oughties. Maybe powder technology, most likely in the deterrent coatings, has moved on making propellants easier to ignite and with more consistent burning behaviours and/or small rifle primers have improved their effectiveness greatly.
The other main changes are that the Palma case usually needs a slightly heavier charge than the LRP type to get the same MV, around a half grain in charges around the 45-47gn level, and that cold weather performance / reliability can be degraded the exact temperature at which undesirable effects kick in being related to the powder type and how easily it ignites. I found that some otherwise untemperamental grades started to see increased ES, groups and reduced MVs at anything below 5-deg C / 40F. Recently I got a load of hangfires and two complete misfires out of a box of 50 trial loads with Hodgdon CFE 223 in around 13-deg C ambient temperatures, on or a bit above 50F. So, certain ball powders are apparently a bad idea in this version of 308 in at least cool conditions.
all the best
Trevor
