Wasn't it the NRA selling dodgy 308 ammo last year that blew up a few rifles at bisley.
Infact I swear I saw them selling said ammo of cheap with a disclaimer!
That's an interesting case which moreover underlines how difficult any regulation would be.
The ammunition wasn't 'dodgy' at all - it conformed exactly to CIP 308 Win specs. The 'dodgy' bit is that most TR rifles don't conform to 308 Win specs in that they have 'tight' bores, a hangover from the days when they were expected to perform with 7.62 military ammunition and undersize bullets. Whilst today's TR barrels aren't specced anything like as undersize as was once the case, they remain a thou' or two tight on the bore dia. and a few tenths of a thou' likewise on groove diameter. (Why TR rifles haven't been specified at SAAMI levels for years, I simply don't understand. It's not just us and the British Commonwealth TR shooting countries, but the top US 'Palma' shooters also use barrels with similar or same dimensions. US 'any ammo' sling shooters mostly use standard spec blanks however, so the handloaders are working to SAAMI/CIP regulations; national teams break them and need underloaded ammo.)
The NRA contract with RUAG for the RWS ammo loaded with the older 155gn 308 Sierra MK (p/n 2155) was extremely tightly specified to give maximum CIP pressures in such barrels. It was actually
underloaded for CIP/SAAMI spec (0.300/0.3080") dimensioned barrels. This worked fine for a couple of years, but then for some reason or other RUAG forgot this or just plain cocked it up and loaded a year's worth at full CIP pressures. Results - over-pressures in new TR rifle barrels, or those at the small end of the tolerance range. The NRA then returned the ammo as 'out of spec', ie out of their contract spec. On its return, RUAG retested the ammo in a CIP-spec test barrel (0.300/0.3080) and found it was 'within CIP', although one imagines by not a lot. It then unpackaged all the returned cartridges and repackaged them in standard 308 Win Sierra MK match ammo boxes and put them back into the market, some or all ending up here. This of course caused all sorts of problems as people inevitably fired them in 'tight-barrel' 308 TR rifles, so the NRA had to put safety warnings out about its use.
All this shows is that when peak chamber pressures are at or close to maximum, relatively small firearm / chamber changes can affect results one way or another. Take 223 Rem as an example. The standard SAAMI 223 Rem chamber has a 25 thou' length throat (ie 'freebore') and 3-degree leade angle. The popular Wylde' match chamber used in nearly all straight-pull 223s by the CSR crowd among others, has a 62-70 thou' 'freebore' and much longer /gentler leade with a 1.2 to1.5-degree angle depending on chamber variant. The FTR shooters using the 223 mostly have chambers cut with the PT&G '223 Rem ISSF' reamer that produces 169 thou' 'freebore' and the users handload 80-90gn bullets also specifying one turn in seven-inch rifling twist pitch. My first long-range 223 F-Class rifle had a custom chamber with over 200 thou' 'freebore' that produced an optimal seating position for the 90gn Berger VLD and a COAL of c. 2.79" compared to the SAAMI 223 maximum spec of 2.26". A perfectly safe maximum charge for a say 69gn or 80gn SMK in a Wylde chamber is way over that quoted in handloading manuals or online data because the manufacturers' loads are based on test barrels conforming exactly to the SAAMI 223 Rem specs.
Then there is the little matter of just what is a maximum book load? Taking five current manuals' loads data for 223 Rem including Hodgdon's own figures, the maximum charge for H. VarGet under the 77gn SMK seated to 2.26" vary by 2.9gn from lowest to highest. 2.9gn is a lot in any cartridge, but in 223 Rem with this bullet, it is MASSIVE! A full grain of powder changes Pmax by c.5,000 psi in this combination in Winchester or Remington brass!
As with so many things, everything hangs on the individual handloader's knowledge, expertise, and general taking care / competence. If the MoD insist on 100% assurance, we'll end up with some sort of training / testing regulatory regime. We all know just how well that works don't we as every vehicle driver has to be trained / tested / licensed and of course they all drive faultlessly and expertly don't they?
