RKG 3 - M79 Heat Grenade
Roly Evans
All,
We have quite a few RKG3 and M79s out here to get rid of.
I know EOD operators who designate these items no touch in any circumstances. I believe this dates from the mid 1990s when soldier in Bosnia was killed unscrewing the handle/fuze of a reportedly pinned grenade.
In May 2000 the following came up in the UNMACC Threat Factsheet IN Kosovo.
We have been sent some information from our counterparts in Sarajevo regarding
the M79 heat grenade, production faults have been reported in the more recent models
and this can lead to a deliberate removal of the safety mechanism. Therefore the unarmed
state of the grenade cannot be confirmed by a visual inspection. All M79 grenades are to
be treated as armed from now on. All mine clearance personnel are to minimize their
exposure to this grenade.
Does anybody have any info what is going on with the fuze on both the RKG 3 and M79?
We have all the usual diagrams etc.
Basically any info on why this fuze could be malfunctioning is welcome.
Many thanks
Colin King
Hi Roly,
I looked into that accident when I was doing the ‘MOD job’. My understanding of the cause is reflected in the entry that currently appears under Notes in the Anti-armour hand grenades record in Jane’s EOD:
It is important to note that if the fuze cover securing staple is not present, unscrewing the handle may result in extension of the mechanism, which is likely to arm the fuze; subsequent tilting or jarring may then cause initiation.
If you know the structure and the staple I’m talking about I hope, hopefully that will make sense. Either way, it would be wise to keep them horizontal or tilted handle-down if they have to be moved.
Best regards,
Colin.
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Roger Hess
Hi Roly;
If you look at the diagrams both of these items have a common design feature in the fuze which is a spring loaded firing pin. Unlike an external one that you have on many hand grenades there is no access to this which means aside from doing a dearmer shot there is no positive way to gag that pin, so by picking it up you could be doing the equivalent of handing a cocked mouse trap with an HE charge attached to it.
If you don’t have dearmers (which many groups don’t) you can easily fabricate a tool to do the same with a small bit of HE and a metal plate; if you’re interested in doing this contact me off line and I can walk you through it.
Cheers
Roger
From: demi...@googlegroups.com [mailto:demi...@googlegroups.com] On Behalf Of Roly Evans
Sent: 28 January 2011 9:50 AM
To: demi...@googlegroups.com
Subject: IGEOD: RKG 3 - M79 Heat Grenade
All,
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Roly Evans
Hi All
Thanks to Marceau, Colin and Roger.
To be crystal we are asking about the item when both fly off handles, alongside the end cap, are still in place, retained by the safety pin.
Marceau, according to the attachments you sent in this state it is safe to move. Or should all M79s be handled with caution given possible manufacturing defects? (Faulty retaining balls– safety rod – retaining sleeve?)
If I understand the replies sent so far if the grenade is complete with the fly off handles, end cap and safety pin there no massive problem?
Also, if problems with this have only happened in the Balkans are we just talking about the M79? Nobody heard of issues with the RKG elsewhere?
Cheers all.
Marceau Guilbaud
| Hi, For me, as I always eared, never saw directly, even with safety and handle in place, when you unscrew the two parts, it is possible to release the striker. It is the reason I worked carefully. With a new one external aspect I could try to unscrew and I did it before with some took directly in storage case. If I remember well, the booster is put in place just before using by the launcher. I don't remember if the safety pin pass through the striker and I haven't one behind me to have a look. But I think no and it could be the reason why the striker could hint the booster even with
safety and handle in place. For me, it will be the same for each grenade that receives the same principle of functioning. Take your head between yours knees. Marceau Guilbaud --- En date de : Ven 28.1.11, Roly Evans <Roly....@maginternational.org> a écrit : |
Colin King
As far as I can see, the issue with the missing staple is that – without it – an attempt to unscrew the handle/fuze assembly may just move (extend) the outer housing. Extension allows the central safety rod to move back (as would normally happen when the drogue deploys) so that the retaining balls fall inwards to free the striker collar and inertia weight. This would leave the grenade fully armed, although the safety pin and both fly-off levers would still be in place.
The key is the outer section unscrewing from the fuze assembly cover to cause the extension – that’s what the staple is there to prevent. As far as I know, all of the Russian and East German RKG-3 variants and foreign copies have this staple and therefore all are potentially liable to the problem if it’s missing (or corroded?). One of the issues is that we may not be using standard terminology, so attached is an image of the staple I’m talking about.
Roly Evans
Thanks Colin – that’s great. Every day is a school day!
Think the staple is clearly identifiable on the attached. Robin – apologies if 181kb is too big - any smaller and the image was too poor.
Thanks all.
Roly
Roger Hess
Hi Roly;
After looking closer at all the diagrams I have, I would say Colin has identified the potential weak-link with the fuzing mechanism (good job as always Colin).
Cheers
Roger
Bomb Disposal Club Admin
| Roly, In my own humble opinion I think with the Expert advice given by both Roger and Colin, if there is no requirement to move said M79's then don't and also to note that although the information from both Roger and Colin is second to none in the EOD community, the only person who can make that call on whether to go unscrewing the Fuze assembly from the weapon, blowing In-Situ or 'In Place' (as Roger and Co would call it :) or moving the weapons without separating the Fuze Assembly from the main charge, is yourself or your EOD Operators on the ground, it is one thing asking for advice etc. on a Forum and quite another being on the ground and assessing the situation and making that call for ones self, whatever you decide to do is your decision based on your own experience, training and knowledge of EOD. I knew
Peter Bradley (known as Brad to most of us) very well, in fact I took over from him in Gornji Vakuf in 96 and was amazed a year later when I was ending another tour out there when Brad took over from me again in G.V. in 99 I was with a local demining team in a very heavily mined area near Bugojno called Kopcic and heard that Brad was back again! so after our days work I headed to the Precission Factory to see him only to be told by a young Sapper in the Ops room that he was on R&R, we completed that demining project a few days later and I very unfortunately never saw Brad again as he was killed shortly after coming back from R& R in Bugojno while carrying out what is known as 'Op Harvest' where locals are encouraged to bring in weapons, mines and other ordnance to bunkers outside of SFOR camps, I still think to this day that it was an ill thought out operation as it encouraged civilians to handle ordnance they knew nothing about; Brad was a good
EOD Operator and a great guy and no one really knows what exactly happened that day but information does point to the M79 being 'made safe' as in fuze assembly being separated from the main charge as was the norm and the same method used by all of us on hundreds, if not thousands of M79's over several years, young Ben Dillon who was severaly injured at the time was the closest survivor that day and I don't think he even knows exactly what happened, I believe Colins understanding of the staple being missing or removed is what happened that day. Incidentally the strange thing about all 3 lads who were killed (2 in 94) is all three had the first 3 initials used in their names or nicknames, young Barrie Nicholas from my own troop, Barney Warburton and Brad from 58 Sqn. Good Luck with the project. And Stay Safe. AL... |