The Parker-Hiscock
Images
courtesy of Richard Loweth.
Another conversion of the SMLE to .22 caliber
rimfire (sleeved barrel) was the Parker-Hiscock, again this one was designed
for use as a military training rifle. The Parker-Hiscock utilized a modified
bolt and a complex magazine to simulate cocking and chambering a full sized
.303 round, but actually only using .22 caliber rimfire cartridges.

The magazine carried 5 rounds of .22 LR to enable a .22 caliber SMLE trainer (with a slightly modified bolthead) to be used for rapid-fire training. Here the bolt is closing and bearing on a rod (the magazine itself) that pushes into the chamber a .22 cartridge.

Here the bolt is half closed. The round is moving into
the chamber as the rod pushes it further forward.

Here the round is nearly fully chambered. The
bolthead, as it continues forward, will now contact the "ramped" area
just in front of it and push the whole of the magazine internal workings down
into the magazine body and out of it's path.

With
the magazine internals now pushed down and out of the way, the bolt can now
close on the chambered cartridge. When the trigger is pulled the cartridge will
fire. Opening and pulling back the bolt fully to the rear will eject the fired
case and return the shooter to the position in the first picture.
The Hiscock is a clever device, as successful
use can only be achieved by fully working the bolt through the same travel as
needed to load, chamber, fire and eject a standard .303 cartridge. Indeed when
in use the Hiscock user "feels" just as if doing just that.
Unfortunately, the magazine was complicated and required careful maintenance
and a degree of proficiency in use. As such, the Parker-Hiscock seen limited
use as a military training rifle.

Left:
a normal SMLE bolthead. Right: a modified Hiscock bolthead.
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