6 mm Musgrave

Infobox Firearm Cartridge
name= 6 mm Musgrave


caption=
origin= RSA
type= Rifle
service=
used_by=
wars=
designer= Ben Musgrave
design_date= 1955
manufacturer=Musgrave
production_date=
number=
variants=
is_SI_specs=
parent=.303 British
case_type=Rimmed, bottleneck
bullet= 0.243 (6 mm)
neck= 0.338
shoulder= 0.401
base= 0.460
rim_dia= 0.540
rim_thick=.064
case_length= 2.222
length= 3.075
case_capacity=55.7
rifling=1-10 inches
primer=Large rifle
max_pressure=49,000
max_cup=45,000
is_SI_ballistics=
bw1=80
btype1= SP
vel1=3120
en1=1729
bw2=85
btype2= SP
vel2=3084
en2=1795
bw3=90
btype3= SP
vel3=2950
en3=1739
bw4=100
btype4= SP
vel4=2805
en4=1747
test_barrel_length=24"

The 6 mm Musgrave was the brain child of Ben Musgrave and introduced by Musgrave Fire Arms in 1955 and can be described as a classic Africa cartridge. It is based on necking down the .303 British with the original intent of it being a Springbok calibre for hunting on open plains in South Africa's Karoo, Kalahari and Namakwaland. It is also well suited for other smaller antelope where longer shots have to be taken. Although not designed for bushveld conditions, the calibre can be downloaded to drive 100 grainers at 2500 feet per second and makes a very good cartridge for Impala and Reedbuck.

Like the .243 Winchester it has a fast rifle twist of 1-10 inches, however if 105 grain bullets are used it is recommended that a 1-9 or even faster twist is used to stabilise the bullets.

PMP (Pretoria Metal Pressings) is one of the very few ammunition manufacturers of 6mm Musgrave ammunition, but a lot of South African distributors have the ammunition in stock. A lot of international manufacturers (like Hornady, Nosler, Barnes, etc.) also manufacture 6mm bullets and as such there is no real problem for the reloader either.

The 303 case has a larger capacity than the 243 case but is loaded to lower pressures (SAAMI spec 45 000 compared to the 54 000 for the 243). The lower pressure is due to the actions on which most of these rifles are built, the Lee Enfield action. Musgrave started quite a large “manufacturing” operation, building rifles on military surplus actions (both Mauser and Lee). The 6mm Musgrave was built by simply rebarreling the 303.

Even at these lower pressures, the cartridge is almost on a par with the 243. Of course handloaders can improve this and the round is capable of well exceeding the 243, but this doesn’t work in the Lee action (it is claimed that the “flex” in the Lee action results in head separation after a few shots if high pressures are used).

This load is also popular in Australia as a wildcat. Part of the popularity of this load is the fact that old Lee Enfields are available for next to nothing.

This is a truly “African” caliber that has proved its mettle over the years.

ee also

* List of rifle cartridges
* 6 mm caliber

References