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  M61 Fragmentation Grenade (Vietnam)
M61 Frag Overview

After WWII, efforts were under way to improve upon the cast iron Mk.II design.
The problem with a grenade that produces limited heavy fragments is consistency of coverage. Many times, even close to the point of detonation, the schrapnel coverage could be spotty.
On the other hand, the heavy fragments can have lethal effect far beyond the intended target area. Experience showed that hand grenades needed to be more effective close in, and long range hazards needed to be minimized.

Towards that end, a new class of grenade was developed. A high yield limited range fragmentation grenade.

The first of this type was the M26, developed prior to the Korean War. The M61 is an improved version of that. It has a light sheet metal body, with an internal fragmentation coil, producing a more uniform and effective casualty radius (15 meters).
M204A2 Fuze w/Jungle Clip The Jungle Clip

The M61 incorporates a secondary safety feature called the "Jungle Clip".

While never a design intent, grenade safety levers have long been used as a convenient carry hook, clipped over web gear. Experience in Vietnam showed that jungle growth had an unfortunate tendency to snag hand grenade safety pins. The jungle clip is a secondary back-up safety device, used to clamp the lever to the grenade in the event that the pin is accidentally pulled.

Shown here is the first model. A simple add-on wire part. When unhooked it remains attached to the grenade.

The grenade now required two separate arming actions, releasing the jungle clip and pulling the pin, prior to throwing the grenade.

M61 Sectional View M61 Frag Coil

Above is a view inside the grenade, from the open base.

At left is a sectional view of the interior of the M61.
Shown is the internal fragmentation coil. Nested around the detonator are tetryl booster elements, which assisted detonation.

The M204 fuze delay is completely contained, resulting in an almost silent fuze which didn't emit sparks or smoke, a big improvement over earlier WWII designs.

M30 Practice
Will the Real "Lemon Practice" Please Stand Up!

Seems no end to the supply of "Authentic" U.S. Military "Lemon" Practice Grenades out there today... more common than crabgrass.
Purely a commercial effort for the general curio market they have no historical significance, other than the expended military fuzes.
Finding an authentic example of the actual grenade type will prove a tad more challenging.

First, Some Real "Lemons"....
M30 Practice, (left) - M62 Practice, (right), the later varient.

The primary difference between the two is the presence of the jungle clip. Both use M205 Series Fuzes.

Note the two different cross-sectional lever styles, flat and U-channel. "M205A1" is found stamped on the flat style; "M205A2" has been observed on both styles. Both can be found on the M30, but the M62 would only use the U-channel type, along with the free hanging jungle clip, as it's purpose was Jungle Clip training.

(Not sure about the white ink in the embossed letters - Probably a visual enhancement, as with some firearms where markings on receivers are filled with white ink.)
M62 Practice

CrabGrass Now the Fake "Lemons"....

Key Identifying Features:

o Fuze Thread.
Curio bodies were made specifically to take advantage of available spent M228 fuzes that found their way to the scrap metal market.
The fuze threads were sized accordingly (UNC 5/8-11).
o The resulting presence of the M228 Fuze (or sometimes the M213).
Note the characteristic "kink", rather than a smooth curve profile for the lever, as well as the shorter length.
The M205 series fuze has a smaller diameter thread (UNC 9/16-12), which doesn't fit.
o Curio's overall casting quality is poor.
The embossed "RFX" characters are irregular.
The metal alloy is not the same.
Grind marks, from smoothing rough cast edges, tend to be significant but there are exceptions.