[Unclenick]

Originally Posted by Ike666

Powder: load #1 40.0 grains IMR 4064, load #2 41.5 grains IMR 4064
Load Data: Lyman Reloading Guide

Load #1 is the start load in the Lyman Guide, but load #2 is the start load on the Hodgdon website.

Next time you use the Hodgdon site, click on the button along the top named "print". You will get the barrel length, case, and primer used in the test loads. The cases are almost always Winchester, including the loads for .308 Winchester. Winchester .308 brass is a design developed originally for the 1992 Palma match to have more powder capacity than conventional .308 cases. They weighed an average of only about 156 grains last time I bought some new bulk Winchester. Lake City usually runs about 179 to 181 grains, or about 24 grains heavier on average. The specific gravity of 70:30 cartridge brass is just over 8.5, so that difference translates to 2.8 grans of difference in case capacity, which means around 1.5 grains less of most rifle powders will produce the same pressure in Lake City brass that it does in Winchester. So, reducing the Hodgdon load data from 41.5 to 40.0 to get a starting load for your LC brass is perfectly reasonable.

Federal loaded its Gold Medal Match 168 grain SMK load for years with 43.5 grains of IMR4064 using its own 205M primers. Federal cases (IIRC; can't seem to lay my hands on any here to double-check) were about like other non-Winchester commercial cases, and weighed around 170 grains. So you could expect 42.8 grains in your LC cases to give about the same pressure and barrel time performance as Federal's own 43.5 grain load. Just slightly less velocity (20 fps or so).

As to the primers, they do look a bit extra flat. That usually happens because the head mushrooms (the exposed part sticking out fattens) under pressure so that when the case heads stretch back to reseat the primer, they not only are flattened, but that swollen mushroom head is squashed wide to fill the radiused lip of the primer pocket.

However, the edges of the primer firing pin indentations are not squared, much less cratered, so I doubt the pressure was actually excessive (though primers are not the most reliable indicator; just a convenient one). It seems more likely the very flat spread is due either to cases sticking to the chamber walls more firmly than usual so that the head stretching back is delayed a little, which will grow the primer mushroom head, or to excess headspace. One way to check would be to neck size some of these cases, load them singly and gently (chamber fast with a bolt can shorten them), and then run the same load. That way the primer won't have any headspace to back out into, and you can see if that extreme flatness is mitigated?

I would also take a depth mic or use the head step of a caliper to measure how far out your first set of primers are sticking? That should tell you how much bigger your headspace was than the sized cases were. I can't tell if it's really excessive from the photos because of the rounded edges of the primers, but it looks like it might be on the long side, which could also cause the broadly flattened primer by letting it back out farther enough than normal to mushroom more than normal. Figure that if you chambered the rounds slowly and without slamming the bolt, you shouldn't see those stick out more than about 0.010", maximum. This would be if the brass were sized to -0.002" under minimum chamber headspace when you started, as is fairly normal for new, unfired cases.

That leaves the sticking bolt. If some high pressure event is actually occurring, your velocity should be too high for the load with your barrel length (I don't know what that is?). So a chronograph is a good idea for a reality check here. Things other than high pressure can cause bolt sticking, though. We had a thread not too many months ago in which a fellow had some 1960's LC cases ('68, maybe) that were giving him sticky bolt lift even with starting loads. He had to back down to around 32 grains to get it to stop, IIRC. I sent him a few new, unfired LC cases, and he tried them with the same starting load and had no sign of sticking. We never did figure out what had happened to the old LC cases? Had someone over-annealed them, leaving them too soft to spring back after exposure to normal chamber pressure? They sure behaved that way. I don't think he knew who fired the brass originally or how many times or if it had been annealed. Or perhaps that brass had simply been stretched too far by extraction in a machinegun and gotten to too thin to spring back from the breech? Don't know. We just know the sticking stopped when he used known good cases. It wasn't caused by of exceeding normal pressure for the round. It was just excessive pressure for those particular cases.

So, based on the above, I would do the same cross-check. Get some new cases and load them per their weight and see if sticking stops and primers are any less flat? The way to calculate weight for constant barrel time (pressure moves just a couple hundred psi in QuickLOAD this way, so not significant) is the simple linear equation below. Note that this only applies to mimicking the barrel time of the Federal Load with the 168 grain Sierra Match King seated to 2.800" COL and using a Federal 210 or 210M primer, and is not for any other combination:

Adjusted IMR 4064 Charge = 55.1 grains – (0.0682 × case weight in grains)

Thus, a 186 grain IMI Match case should be charged with:

55.1 gr. – (0.0682 × 186 gr) = 55.1 gr – 12.7 gr = 42.4 gr IMR 4064


A 180 grain LC case should be charged with:

55.1 gr. – (0.0682 × 180 gr) = 55.1 gr – 12.3 gr = 42.8 gr IMR 4064


A 156 grain Winchester case should be charged with :

55.1 gr. – (0.0682 × 156 gr) = 55.1 gr – 10.6 gr = 44.5 gr IMR 4064

QuickLOAD says these are not maximum loads and should be running in the vicinity of 52,600 psi, give or take a few hundred. That agrees well with Hodgdon's data on the Winchester case, for which the maximum is given by them as 1.4 grains higher (45.9 gr).

So, to test if the LC cases may be bad, get whatever new case you can or even use a good condition range foundlings or cases from commercial load that were fired in your chamber for the first time and did not stick would be better still. Size and decap and clean these. Weigh them. Calculate the above load, knocking the result down 5% and working up in 3 steps to arrive at the above load. 5% and 3 steps rather than the usual 10% and 5 steps should be good enough in this situation as we are not working up to a maximum. You should not get case sticking at any level.

If you prove to yourself that the sticking is gone, then run Dan Newberry's round robin to fine tune to the very best load. That varies with the gun. If you wind up running in the pressure range of the old Federal load (they now use Reloader 15, BTW), that will be good for excellent barrel life.

Nick