Tough Brass — Peterson .308 Win Brass Strong After 32 Firings

Here are five Peterson .308 Win casings after 32 loading/firing cycles (31 at SAAMI max). The brass remained intact, with no cracks. The circles below the shoulders are markings from pressure testing.

This story comes from the Peterson Cartridge website.

Torture Testing Peterson .308 Win Brass — 32 Load Cycles

Recently Peterson’s ballistician had some extra time in his schedule, and asked what he should work on next. He was told, “Just for the heck of it, see how many times you can fire our .308s before you experience failure.” So that’s what he set out to do.

He took five casings out of inventory and loaded them at SAAMI max pressure, which is the pressure we use for all of our longevity testing. It is a hot load, and he did the firing out of Peterson’s Universal Receiver. This way he could measure pressures and velocities each shot. He shot all five, 20 times. (It takes a long time to do that. Load five casings. Shoot five times. Back into the lab to reload, back into the indoor range to shoot, back into the lab, and so forth.)

After 20 firings with no sign of case deterioration, Peterson’s tester asked if he should keep going. “Sure, let’s see how long these can go”, was the reply. So he shot them five more times. Same result. All casings still in good shape. We told him to keep going. He shot each of them six more times. At this point each of the five casings had been fired 31 times. After several days of this the casings were still in good shape but “ballistician fatigue” was setting in. Finally he said, “Let me take these cases to an outdoor range and see how they do for accuracy.” The Peterson team agreed.

Five Shots at 100 Yards after 32 Load Cycles:

For the 32nd firing, the cases were loaded with a somewhat lighter load, and then tested for accuracy. The test rifle was a Tikka T-3 bolt action, with a 20 inch, 1:11″-twist barrel. After 32 firings the primer pockets had opened about 0.002″ (two-thousandths) but were still tight enough for further use. There were no cracks or signs of head separation. The tester put five shots in three holes at 100 yards. The group was 1.5 inches for the five shots, on a somewhat windy day.