Single shot bolt action target rifle. Receiver marked SPORTCO MODEL 44 over Made in Australia by OMARK 7.62 mm Cal and the serial number. The butt has a storage scar to the lower section and has a fore sight element box screwed to the pistol grip, which contains three inserts being a blade, a flat and an aperture. So what sort of serial number prefix are we talking about for an early production Sportco Omark? Roger buckland., 05:30 PM. Anyone have a set of sights for sale that will work with that year and model of Omark mod 44? Thank you in advance for the help and advice. Bill Wylde - SE Illinois., 07:16 AM.

Rifling Twist Rate

By Chuck Hawks

Inside of a rifle barrel there are spiral grooves, called rifling. These are intended to spin the bullet to keep it stable (point on), without wobbling or tumbling, during its flight to the target. The tighter the spiral grooves, the faster the bullet spins. The tightness of the spiral is called the 'twist rate.'

The rate of twist is expressed as one turn in so many inches (i.e. 1 in 10' or 1:10). The caliber, length, shape and velocity of a bullet determine its optimum twist rate. The standard twist for a rifle barrel is designed to stabilize the range of bullets and velocities normally associates with that particular cartridge out to very long range. Spinning a bullet markedly too slow or too fast is detrimental to accuracy.

It takes less twist to stabilize a given bullet at high velocity than at low velocity. At the same velocity in the same caliber, longer bullets require faster twist rates than shorter bullets.

The Omark Model 44 is a bolt action single shot target rifle made in Australia. First released in 1968 as the Sportco Model 44 produced in Sportco 's Adelaide factory, production was taken over by Omark in the 1970s, then by MAB Engineering in Brisbane in 1984. Rifle - Omark Mod.44 308 Single Shot Bolt Action Competition Rifle - Serial Number DB546 - (Dealer Tag F882) (B Class Firearms Licence Required) $200.00 start Item is closed.

A faster twist increases pressure, barrel wear and also the strain on the bullet jacket, which can actually come apart if spun too fast. This particularly applies to frangible varmint bullets, which have very thin jackets, fired at high velocity in very fast twist barrels, such as the 1 in 7' twist barrels supplied on many .223/5.56mn AR-15 type rifles.

Fortunately, the rate of twist chosen by the rifle maker is usually appropriate for the intended cartridge. Anyone ordering a new barrel for a hunting rifle will generally do well to specify the standard twist as supplied by the major rifle manufacturers for that caliber. Where there are two twist rates in common use, for example 1:10 and 1:12 for the .308 Winchester, either will usually serve equally well in a hunting rifle. Many other factors are more important to accuracy and performance than twist rate.

Once in a great while, though, a manufacturer makes a mistake. One such case involved the .244 Remington, introduced at the same time as the .243 Winchester. When first introduced, barrels for the .244 were made with a 1:12' twist, because Remington anticipated that their new cartridge would be used primarily for varmint shooting. The 1 in 12 inch twist is ideal for best accuracy with varmint weight bullets (70-85 grains) in a high velocity .24 (6mm) caliber rifle. The heaviest spitzer bullet that a .244 with a 1 in 12 inch twist barrel could stabilize was 90 grains. .243 Winchester barrels, on the other hand, were rifled 1:10' to stabilize bullets as heavy as 105 grains.

It turned out, most customers wanted to use their new .24 caliber rifles for hunting medium size big game, with 100 grain bullets. Needless to say, .244 sales languished while .243 Winchester sales soared. Remington soon saw the error of their ways and changed the rifling of their .244 barrels to 1 turn in 9 inches, but the damage was done. Sales remained so slow that eventually Remington had to discontinue the .244. The following year they reintroduced the exact same cartridge as the 6mm Rem. and produced all 6mm rifle barrels with 1 in 9 inch twist barrels, which can stabilize all .24/6mm bullets.

Another peculiar rifling twist story involves the .223 Remington, called the 5.56mm NATO by the military. This cartridge was designed specifically for use with 55 grain spitzer bullets and its twist rate was originally specified as 1:14'. This was later tightened to 1:12' for long range shooting, which works very well with bullets weighing 40-60 grains, the usual .22 centerfire bullet weight range.

Years later, the military decided they needed more penetration, so they increased the normal service cartridge bullet weight to 62 grains and some military cartridges use bullets at heavy as 77 grains. Meanwhile, some hunters could not resist trying their .223 rifles on small deer and they also used heavier bullets, up to about 70 grains.

The standard 1:12' twist could not properly stabilize these heavy bullets, so the military went to a 1:7' twist, designed to stabilize bullets weighing 62-77 grains. Most manufacturers of AR-15 type civilian rifles followed suit.

Unfortunately, 1:7' is too fast for frangible varmint bullets, so now we have two 'standard' twist rates for .223 rifles: 1:12' for varmint rifles and 1:7' for military type rifles. The latter are often, but not always, stamped '5.56mm.'

Here is a formula for calculating twist rate:

Here are the usual twist rates for most of the popular rifle calibers. (For a more comprehensive list, see the expanded 'Rifle Barrel Twist List' on the Tables, Charts and Lists page.)

.17 HMR = 1 in 9'
.22 Long Rifle = 1 in 16'
.222 Remington = 1 in 14'
.223 Remington = 1 in 12' (varmint rifle)
.223 Rem./5.56mm NATO = 1 in 7' (AR-15)
.22-250 Remington = 1 in 14'
.243 Winchester = 1 in 10'
6mm Remington = 1 in 9'
.240 Wby. Mag. = 1 in 10'
.25-06 Remington = 1 in 10'
.257 Wby. Mag. = 1 in 10'
6.5x55 Swedish Mauser = 1 in 7.5'
.260 Remington = 1 in 9'
.264 Win. Mag. = 1 in 9'
.270 Winchester = 1 in 10'
.270 WSM = 1 in 10'
.270 Wby. Mag. = 1 in 10'
7x57 Mauser = 1 in 9'
7mm-08 Remington = 1 in 9.25'
.280 Remington = 1 in 9.25'
7mm WSM = 1 in 9.5'
7mm Rem. Mag. = 1 in 9.25'
7mm Wby. Mag. = 1 in 10'
.30 Carbine = 1 in 16'
.30-30 Winchester = 1 in 12'
.308 Winchester = 1 in 12'
.30-06 Springfield = 1 in 10'
.300 WSM = 1 in 10'
.300 Win. Mag. = 1 in 10'
.300 Wby. Mag. = 1 in 10'
7.62x39 Soviet = 1 in 10' (Ruger)
.303 British = 1 in 10'
.32 Win. Spec. = 1 in 16'
8x57 JS Mauser = 1 in 9.25'
.338 Win. Mag. = 1 in 10'
.340 Wby. Mag. = 1 in 10'
.357 Mag. = 1 in 16'
.35 Remington = 1 in 16'
.35 Whelen = 1 in 16'
.350 Rem. Mag. = 1 in 16'
.375 H&H Mag. = 1 in 12'
.378 Wby. Mag. = 1 in 12'
.416 Rem. Mag. = 1 in 14'
.416 Wby. Mag. = 1 in 14'
.44 Rem. Mag. = 1 in 20'
.444 Marlin = 1 in 20'
.45-70 Govt. (Marlin and Ruger rifles) = 1 in 20'
.450 Marlin = 1 in 20'
.458 Win. Mag. = 1 in 14'
.460 Wby. Mag. = 1 in 16'

Not all rifle barrels of the same caliber have the same twist rate. A fellow ordering a custom rifle may have his own ideas about twist, as may the builder. For example, some .270 Win. barrels are rifled with a 1 in 12 inches twist, some .30-06 barrels are also rifled 1 turn in 12 inches and some .300 Magnum barrels are rifled 1 turn in 14 inches.

Usually these variations make no appreciable difference. Slower twists may give slightly lower pressure, as well as very slightly better accuracy with the lighter bullets in each caliber. They will still stabilize the heavy bullets over practical hunting ranges. However, they might not be the best choice, or quite as accurate, for shooting heavy bullets at extreme range (such as 600-1000 yards).

The Angel M80 Rifle is a 7.62×51mm single shot target rifle designed and made in New South Wales in Australia by Bill Angel in the 1980s. The Angel action was one of the first solid cylindrical type target actions (described as 'rigid massive') made in that country. It followed the success of the Swing design in the UK which saw the move away from 'open' designs; often derived from 19th Century military actions. It was approved for use in Australia on 1 November 1980.

The Angel was the first action available in Australia which was strong enough to support a floating barrel.

The design emphasis was on creating an action where distorting effects were minimized. The action was cylindrical with a small side loading port. Recoil was borne through a slot cut in the six o'clock position halfway along the action. A piece of tool steel was bedded in the stock and mated into the slot to form the recoil lug. It was claimed at the time that this feature resulted in less distortion of the action during firing and prolonged the life of the bedding. The position of the bedding screws, close together and near the trigger, was similarly claimed to minimise distortion in the action.

Locking was achieved by a solid bolt head and three bolt lugs. The bolt head was designed to be removable thus allowing the owner to vary the head space by replacing the head. The bolt head is of the floating type whereby it is a loose fit in the bolt tube and held in place by a pin, the firing pin passing through a hole in that pin. This allows the locking lugs to self centre with even pressure when the action is locked.

Although of similar appearance to the Sportco(Omark) Model 44 there are no interchangeable parts with the Angel. The Omark has the same style three lug removable bolt head but the orientation of the hole for the pin that attaches the head to the bolt body is at a different angle as is the extractor. The locking lugs for the Angel are a part the action whereas the Omark has the lugs as part of the barrel.

Omark 44 Serial Numbers Diagram

Bill Angel (Production Manager) formed a partnership with Geoff Ayling (General Manager) and Andrew Powell (Marketing Manager) to manufacture and market the rifle under the name G.B. Rifles Pty. Ltd. It had a manufacturing facility at Gosford in New South Wales.

The Angel was marketed as a more affordable local equivalent to the Swing rifles being developed in the UK. At the time these rifles were stated to cost $800 – $1,500 AUD whilst the Angel was available either as an action on its own at $180 AUD or as a complete rifle for $450 AUD. The complete rifle was initially made available with a Schultz & Larsen blued chromoly steel barrel, 26 inches long with a 1 in 13 twist chambered for the 7.62×51mm NATO (308 WIN) cartridge. Other types were made available at the purchaser's request.^[1]

501 Angel actions were made. The majority of Angel rifles were right-handed although approximately twelve left-handed actions are understood to have been made. A model known as a Hawk Angel was made specifically for benchrest shooting.

Approximately the first one hundred actions made were half an inch longer than later versions at the rear of the action. The change to a shortened action was made due to the rear sight hitting shooters when placed fully to the rear and the overhang behind the trigger causing issues with stock geometry.

right-handed Angel rifles were serial numbered starting with AA and then three digits. Left handed models had serial numbers commencing with an LH prefix and the Hawk Angel had a prefix of HA.

Angel made their own triggers.

All actions were fitted with a rear mount for a Central target sight.

The original Angel stock was of a yellow coloured wood with a rounded fore end that was parallel all the way to the tip with a basic cheek piece with no adjustment.

The rifle is no longer in production.

• The underside of an Angel M80 receiver.

• The right hand side of an Angel M80 receiver.

• An Angel M80 bolt (not original handle).

• The left hand side on an Angel M80 showing a Central Mk 4 sight. Woodwork is not original.

• The Angel M80 bolt disassembled.

• A bottom view of the Angel M80 receiver without trigger fitted.

• The Angel M80 firing pin assembly.

• The Angel M80 locking mechanism.

Omark 44 Serial Numbers Doreen

Media related to Angel Rifles at Wikimedia Commons

Omark 44 Serial Numbers Lookup

References[edit]

1. ^'The Marksman', The Official Journal of the National Rifle Association of New South Wales - April 1980

Omark 44 Serial Numbers 222