FNH Gun Blew Up In Owner's Hand Because He Used Reloaded Ammo

The makers of Five-seveN handguns finished their evaluation of the gun the blew up in an owner’s hand and have determined that it was due to his error and not theirs. Details, inside…

Initially, the owner, going by the handle “f3rr37” speculated in an online forum that the gun had fired “out of battery,” which is when the weapon fires and the slide or bolt is not fully closed and all sorts of parts of the gun going flying in the wrong directions. After he sent the gun back, FNH found that the gun failed because the owner used “reloaded ammo,” bullets ammo that he packed himself rather than using factory issued ones. In this case, he packed the bullet with double the amount of necessary powder. The owner says he accepts these findings. Despite the maker’s initial lack of followthrough when f3rr37 tried to escalate the issue through normal channels, FNH eventually sent him a brand new gun free of charge after he sent the busted one back. The uproar f3rr37’s story created in online forums may have helped spur them to action quicker.


1) Don’t make and shoot your own bullets unless you really really really know what you’re doing
2) Don’t ignore your customers on the phone or you’ll have to end up doing your customer service online before a public audience.

Below, the official report by the manufacturer on why the gun failed:


Subject: Five-seveN serial # 386102425

Date: 6-9-2008

The following conclusions are results from FNH USA’s evaluation of the Five-seveN serial # 386102425 sent in to our service facility after a failure using reloaded ammunition.

Upon examination of this pistol we were able to determine that it did not fire “out of battery” and the catastrophic failure exhibited in this example was clearly caused by excessive cartridge pressure generated by reloaded ammunition.

Our examination showed that the shoulder of the case was separated from the rest of the cartridge and it was left in place inside the chamber. The position of this piece of brass shows that the handgun was in full battery when the reloaded cartridge was fire and the excessive pressure occurred. Another indicator that confirmed our findings is the primer extruded back into the firing pin hole and a portion of the case head was stuck to the breech face. This was caused by brass flow back into the leaded chamber indicator hole.

Additionally there was serious damage to the slide assembly which is clear evidence of excessive pressure. The lower edge of the breech face was peeled away and the slide itself was deformed from the excessive pressure. The pressure that caused this damage exceeded OEM ammunition standards.

The FN ballistics laboratory was able to duplicate the catastrophic failure almost identically with 2x the load data provided by the consumer. In this test the shoulder of the cartridge was left in the chamber at the same position as #386102425, the slide was damaged in the exact same way as #386102425, and the cartridge case head seperated in the same manner with the brass flowing into the loaded chamber indicator hole.

The design of the Five-seveN pistol, being a recoil operated delayed blow back system, has key parameters that prevent an “out of battery” firing.

Our established testing data indicates the firing pin will not strike the primer of a cartridge after .1180 inch. of rearward slide travel. With the slide moved rearward .1540 – .1545 inch. (true out of battery limit), it is impossible for the firing pin to strike the primer, at this point the trigger lever does not actuate the lever of the firing pin safety. It was also noted in our examination that the firing pin safety was still fully functional on Five-seveN #386102425.

It is FNH USA’s finding that the catastrophic failure of Five-seveN #38610xxxx was due completely to excessive pressure caused by the reloaded ammunition and was not the result of an “out of battery” firing.

Please be aware that the owner’s manual for the Five-SeveN handgun clearly states on page 4 that FN Herstal declines any responsibility and invalidates any guarantee and liability claims for incidental or consequential damages (injuries, loss of property, commercial loss, lost of earnings and profits, …) resulting in whole ore partly from the use of reloaded ammunition.

If you have lost or misplaced your owners manual please contact our customer service department at 703-288-3500 x122 for a replacement.

Tommy Thacker
Product Manager

FN FiveseveN Warning *Picture Heavy* part1 [FiveseveN Forum]

PREVIOUSLY: Five-seveN Gun Blows Up In Owner’s Hand, Manufacturer Indifferent

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