CAD Modelling
Design Specifications
- Calibre: 15.5mm (.61)
- Ammunition: Repeating: 22g (344gr) ball, Single shot: bullet
- Barrel: 600mm brass / composite, 1 in 900mm twist microgroove
- Power Source: 12g CO2 cylinders / 8g CO2 cylinders
- Magazine: 5 rounds + 1
- Operation: Bolt action repeater, convertible to single shot
- Usage: Repeating: Field, Single shot: Target
- Rate of fire: Theoretical, three seconds between shots
- Length: approx. 950mm excluding supressor / muzzle brake
- Construction: Steel, aluminium, brass, composite, wood
- Mass: approx. 4 Kg
Bolt Action:
Following the pump action prototype, this big bore rifle has been
designed to be operated in the same manner as any magazine fed
bolt action centrefire. The difference is in the separate magazine
needed to store the lead balls. Upon each firing and working of
the bolt handle, an empty CO2 cylinder will be ejected, a fresh
one loaded and a ball loaded into the breech. For firing of
single elongated bullets, the ball magazine is removed to
reveal the loading port and the bullets are loaded while the
bolt is rearwards as in single shot rifles. The five cylinder
gas magazine will still be functional during single shot mode.
Advantages:
Although not in the power range of a PCP, this rifle will deliver
consistent performance over any number of shots, as there is no
reservoir pressure to deplete. As long as the ambient temperature
remains the same, each shot will fire using the same pressure.
This system also makes gas storage convenient, as it eliminates
the need for a gigantic fill tank. For field use, a belt of 12g
or 8g cylinders could be worn.
Power:
A revolutionary hammer and valve design is being tested on this
gun, and will later be transferred to the assault rifle
on a smaller scale. The new valve allows for a new level of
performance from CO2. The gun could also be set up to exclusively
use 8g N2O cylinders with non-flammable lubricant. With a
conventional hammer and valve, this rifle can be expected to
produce around 250 joules at the muzzle. At a temperature of 25C
and using a barrel length of 600mm the maximum potential for a
12g powerlet has been calculated at over 600 joules. Actual
performance will be in the range between the two figures.
Bullpup layout:
This layout makes the gun compact, despite the long barrel, extremely
long bolt mechanism and length of pull. Most of the mass of this rifle
will be behind the pistol grip, so will be more stable on a bipod and
for free standing shots. A lack of large heavy gas reservoir helps
keep the mass down, and the rifle's compact size will make it easier
to carry around. With a 600mm barrel, the rifle's overall length
of 950mm and rear-heavy layout will give it the feel of a carbine.
Status Logue:
15-09-05
Valve designed.
Design of firing mechanism completed.
Layout of rifle finalised.
Scale drawings created.
Valve machined.
17-10-05
Valve tested with various seal materials.
Development of composite seal material.
Barrel material sourced.
Bullet moulds sourced.
02-11-05
Barrel twist rate calculated.
Tooling for button rifling completed.
15.5mm ball ammunition sourced.
Sizing dies created for ammunition.
06-11-05
Barrels button rifled.
More computer modelling of rifle.
16-01-06
Bolt machining completed.
Barrel wrapped in composite, finished and painted.
Muzzle brake testing and machining completed.
Valves and hammers machined for testing.
Barrel tested.
Hammer tube and reservoir machined and polished.
Couplings machined for bulk CO2 testing.
Valves undergoing testing.
.50BMG / 12g cylinder & 15mm ball
typical 4.5mm pellet / 15mm cast slug
Muzzle brake
Microgroove rifling, muzzle prior to crowning
Bolt
15.5mm swaged lead balls
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