8mm in F-class?

[Tim N]

Please explain(recoil reducing devices)
With pics preferably

[RDavies]

Please explain(recoil reducing devices)
With pics preferably

Some use large muscular shoulders to absorb the recoil. I use a Ruckers Bump Buster hydraulic dampened recoil absorber in the (rifle) butt. They are likely a more viable option for you.

[macguru]

If the rifle is under weight , like the savage, 1kg of lead fishing sinkers was all that was needed. With the barnard, i have not bothered. The barrel is so heavy it absorbs alot of the recoil.

[DenisA]

I'm working on an anti recoil device at the moment. Its looks, smells and tastes just like a cupcake, but lots of them.....

[Tim N]

I was just about to sign up at the gym to get the big shoulders but now there are other options available I might conserve my energy.
When you said recoil reducers I was thinking about the other end of the gun with some sort of "legal" muzzle brake

[AlanF]

There is another way of reducing the sharpness of recoil and maintain velocity. Use a longer barrel and slower powder .

[DenisA]

I've been reading up a little on 8mm bullets and cartridges on the net. An 8mm bullet (.323) is actually 8.2mm O.D. The bore diameter is 8.2mm in the groove and 8mm on the lands. Does that mean that 8mm bullets don't actually qualify for the ruling of 8mm and under?

[williada]

Afraid so Denis, you will have to roll your own. The bullet gauge is 8mm on the target.

[Razer]

Quote:
The measurement .303-inch (7.70 mm) is the nominal size of the bore measured between the lands which follows the older black powder nomenclature. Measured between the grooves, the nominal size of the bore is .311-inch (7.90 mm). Bores for many .303 military surplus rifles are often found ranging from around .309-inch (7.85 mm) up to .318-inch (8.08 mm). Recommended bullet diameter for standard .303 British cartridges is .312-inch (7.92 mm).

The standard 8mm range restrictions were possibly the result of the 'umble' .303 military round which just sneaks in to those specs.
At the recommended 7.92mm bullet diameter there is not much between it and the 8mm max.

Interesting when reading the above that the bores had relatively big variations.
Might account for the varying accuracy of some of the old Lee Enfields, some were absolute shockers.

[DenisA]

Ha, ha. I think that's pretty funny... That 8mm's don't qualify for 8mm or under. Its just a name at the end of the day.

[shooter mcreid]

Actually they do qualify as the was a rule modification not too long ago:
(a) An F-Class Open Rifle may be of any calibre up to and including
8mm. When groove diameter is included this is determined as 8.204mm (or .323”)
So keep building that new rifle Dennis

[macguru]

Likewise 308s are really 7.82 mm diameter across the grooves, and not 7.62 (.300) ... Thats .300 across the tops of the lands.

where

303s are really 312s. IE .312 is 7.92 bullet diameter and across the grooves, and not 7.7mm (.303)

so the 308 is named for the bore and the 303 is named for the lands. (edited, i got this the wrong way round) And handgun cartridges get even more confusing !

[pjifl]

Just think of 308 bullet as 30 cal which says it all.

Be careful generalizing about oversize grooves especially for a 303 and also the M17 which was produced in quantity as the US Enfield.

Like any battle rifle production was changed because of wartime contingencies to save production time and utilize readily available tooling.

303 Barrels were made with 2, 4, 5 and I think at times 6 groove configurations. They all shot quite well and qith good barrels were as accurate as each other. I shot a 2 groover for a while and equalled others scores but it never looked quite right ! The ratio of groove to land area was quite different and to assure the right amount of squeeze on the bullet groove depth was deliberately changed with the rifling type. When a bullet is squeezed the metal has to go somewhere and it is the 'average' bore size that matters most.

To complicate matters, US and British practice was to provide a quite different land width. The British rifling used much wider lands. This was to better resist wear from hotter burning Cordite which is a double based propellant.

When the US took over the M17 (it was the P14 British) production in WW1 the Rifling tooling designed and already in existence to produce British Style rifling was retained although the groove depth and bore was adjusted slightly to give the correct squeeze to US 30 cal projectiles. This produced what to US eyes seems quite a different result and was not apparently a Kosher '30' cal barrel.

For a battle rifle it shot just as well and the barrels lasted about twice as long under battle conditions.

When I shot seriously a 303 in competition we had a set of gauges. They are still here somewhere. I cannot remember the sizes exactly but from memory were 303, 30325, 3035 and 304.

A 304 indicated a badly worn barrel definitely not suitable for target shooting.

Of all the military rifles I ever saw of Australian origin which had been approved for issue none ever had the bad barrel tolerances suggested earlier. But, as I said, ignorance often led people to assume the groove size was wrong because of the need for different groove sizes in different types of barrels.

I would beware of much that has been written in the popular shooting journals - especially recently.

Peter Smith.

[macguru]

Thanks for that, and yes
Just think of 308 bullet as 30 cal which says it all.

Yes but I bet if you ask a dozen people "whats .308 in mm?' 11 of them will say 7.62 not 7.82

[williada]

The boys make a lot of sense Denis. If its as simple as calibre related, and not strictly 8mm then have a crack. I put this idea past Ecomeat a couple of weeks ago with a view to making some projectiles in 8mm. I'm a bit over the lack of supply of decent projectiles. Its like the diamond trade, control supply and you control the price. Where will we be when our $ gets to 60 cents US? This will probably happen before the year's out.