Ammolab,
I understand what you are saying, the case head did rupture, and a weak case (due to age or manufacturing defect) is a very probable cause. And (of course) I also agree that the Hakim is not designed to extract the shell with pressure in the chamber, BUT, this does happen—and has destroyed several semi-auto’s – Hakims seem to be especially prone to this.
The Hakim was designed to use ammo with a specific pressure curve. Although it has an adjustable gas system, its range is fairly limited. Even on its lowest setting, it still slings brass over 20 feet with many types of ammo. The systems limit is evident when trying to use Turk ammo. When Turk first came out, I tried to get it to work in several of my Hakims. All but one of my rifles would rip the rims off the case at the extractor (usually blowing out the primer in the process), leaving the case in the chamber no matter what the gas setting was on. The ‘stuck’ case could be extracted with a screw-driver with almost no effort. This tells me that the case was still expanded against the chamber walls when the extraction started. One of my Hakims works fine with Turk – which simply implies that every rifle is as individual and preferential as people are. Some Hakim owners have filed a few extra notches in their Hakim’s gas block to give them a little lower gas setting so that they could use the ‘cheap’ Turk. The consensus is that Turk ammo was loaded for long barreled bolt-action Mauser’s with a slow-burning powder. The slow-burning powder kept more pressure on the bullet throughout its movement down the barrel, giving it a higher velocity without more pressure – in other words, it kept higher pressure against the bullet longer than ammo loaded with fast-burning powder. The problem with this in a Hakim is that the pressure is still too high when the bullet passes the gas port, sending more gas pressure down the gas tube than the design calls for – thus, causing an extraction attempt before the pressure has dropped to a safe level. Most auto-loaders would simply fail to cycle, or their extractor would snap free from the shell, but the Hakim’s beefy extractor and heavy bolt system will usually just rip the rims off the brass (if your lucky – or cause a rupture if your not).
Also, I’m sure 50,000 PSI is not what would be in the chamber during extraction. I’m not sure what residual pressure is needed to cause a case to remain ‘gripped’ against the wall, but it could be as low as 2,000 – 3,000 (or lower). Even with a lower pressure, a case rupture could still be devastating. It’s not really the pressure, but it’s the potential volume of gasses that remain that could raise havoc. Think of a bicycle tire and a tractor-trailer tire—both filled to 60 PSI. If the bicycle tire popped, it might sound like a firecracker, but, if you have ever heard a tractor-trailer tire blow, you know they sound like a cannon going off. Same pressure than the bicycle tire, but vastly more volume.
My point in all this is that a dirty chamber, coupled with 60-year old ammo, coupled with a gas setting set too high for the ammo, could have caused a particular case to rupture in a Hakim that otherwise might not have ruptured if it were fired in a Mauser bolt-gun.
I have also heard that ‘40’s Greek is sometimes re-packed with several different head-stamps, which can increase the difficulty in placing blame on a particular ammo year / lot. I know several people report good results with Greek in semi-autos, but I’d bet – considering its age – that it was likely loaded with slow-burning powder for bolt-guns of the era….
Just a friendly debate
TOM
