The four that my friends and I purchased don't...in three different WOCs too. They'll either first fire in semi properly, then a burst then vent or vent the entire reservoir on full auto and that's only if they fire. With the mags inserted in my WOC (stock BC and nozzle), tried it w/ the stock and a stronger hammer spring, did the fix prowin suggested and it looks like the hammer isn't even depressing the valve anymore. I double checked this w/ the upper receiver off and instead of it venting all the gas on semi as w/ my other working mags, I just get a slight puff noise, no significant gas ex