Forum rules
Please bear in mind that this is an open forum and your posts can be read by all members. If you are in a position that can be compromised by what you are saying on here because someone takes offense and tells your colleagues or your sponsor and that in turn means you are being punished for your posts on here, think before you post!
I won't accept the rubbish in the NRA report about the overly low load of the old 'Accurate-2520' (Lovex DO73.6) ball powder giving rise to pressure wave or detonation effect.
This only applies to large cased cartridges and to overly low charge weights of very slow burning powders. Despite the report's claim that Lovex DO73.6 is such a slow burner, it's nothing of the sort. The original detonation wave effects were nearly always in very large cartridges such as .300 Win Mag and the Weatherby Magnums and used powders at least as slow burning as 4831, but usually much slower still as in those surplus cannon powders such as Hodgdon H870. Bruce Hodgdon initially refused to accept the reality of this phenomenon and ran hundreds of tests in Hodgdon's ballistics lab to produce it, all without ever managing so. It has happened often enough though to be accepted now with a small selection of cartridges and powders and you will find several magnums in loading manuals where the occasional starting charge is relatively close to the maximum and the text says it must not be reduced. Never, ever for 6.5X55mm though or for any powder as fast burning as this one.
However, just to be sure, I hauled out my old printed copy of the Accurate Smokeless Powders Number 2 loading manual going back to the days when Explosia (Lovex manufacturer) produced most 'Accurate' powders. The manual is dated 2000 and has two pages of 6.5X55mm loads.
On page 229 it gives the components and pressures used for this cartridge:
Douglas test barrel - 24"
PMC case
CCI-200 primer
3.025" COAL Minimum
3.149" COAL Maximum
The compilers note that SAAMI MAP is 46,000 C.U.P. pressure, but that the Accurate lab had used its pressure testing equipment on Norma factory ammunition and it had produced 51,000 psi using the piezo crystal method in their test barrel. The listed loads used this method and did not exceed the Norma 51,000 psi value.
2520 (Lovex DO73.6) loads are also given for the 100gn Speer SP and 129gn Hornady SP.
Run the unfortunate Mr D's quoted load for DO73.6 through QuickLOAD and its predictions are right in line with the above. So ..... the NRA's too low charge of too slow burning powder hypothesis is absolute b*ll*x and a little research should have discounted it.
Looking at the cartridge feature pictures shown, they are a different matter entirely - note the damaged / crushed primer cups on the unfired rounds. And where did that neck bulge come from? Anybody who could produce such obvious faults on the cartridge exterior and live with them is capable of anything in my view. Who's to say that round didn't have a substantial over-charge or other such piece of negligence on the inside?
Laurie wrote:Looking at the cartridge feature pictures shown, they are a different matter entirely - note the damaged / crushed primer cups on the unfired rounds. And where did that neck bulge come from? Anybody who could produce such obvious faults on the cartridge exterior and live with them is capable of anything in my view. Who's to say that round didn't have a substantial over-charge or other such piece of negligence on the inside?
Well, from 10 pulled rounds the NRA investigator reckoned the average charge weight was on the bottom edge of "acceptable" as defined in Richard Lee's book...
I'm no expert, but I think the deformed cases and mangled primers probably had more to do with this than the charge weight.
Therein lies the issue as I have already pointed out, Richard Lee's book. If that is the only reference they are using then conclusions drawn from that basis will have to be dubious.
Come on Bambi get some
Imperial Good Metric Bad
Analogue Good Digital Bad
Frankly, it's not a powder grade / charge I'd ever use or recommend in the cartridge, but the mere fact that the powder company tested it and obviously found it produced sufficiently consistent pressures and velocities to put it in its loading manual shows that the powder and charges used were not in themselves dangerous, or at the very least unlikely to be so.
For those who remember the old Portuguese FNM FMJ 'target' ammo in the blue and white cartons in 6.5X55 amongst others, it too was loaded with charges of a very fine grain ball powder with charges that only two-thirds filled the case. It wasn't a great load either as it suffered occasional case obturation problems with sooted up cases and bolts and every now and then a big 'gas dent' in the shoulder.
Having read Gaz's piece (another good one) I then read the original; which I have to say was very interesting...
...one thing that's fairly obvious is that a round like the one shown in the report (with the bulged neck) shouldn't be loaded in a rifle - A question for reloaders on here: when I first started loading rifle ammunition (3/4 years ago) I made some ammo that looked the same (which were dismantled and the case thrown away) - it was caused by winding the seating die down too far and pushing the case neck down by its rim...would that not also put quite a crimp on the bullet?
