Direction of twist in Enfield barrels?

Ned · Post by **Ned** » Tue Apr 04, 2006 5:57 am

JBS

Mate I used to do MFC. Motrar Fire controller .

Also air strikes etc but never in the CP of a artillery battery !!!

Cheers

NED

Post by **Niner** » Tue Apr 04, 2006 8:17 am

But.... here is a work sheet from a high burst registration in FDC school. Looks like earth rotation is not an obvious question. However, this is with observed fire. And don't ask me what any of it means now....I haven't a clue any more.

When I went to Vietnam, I had the 13e20 MOS but they needed Forward Observer team members more. Lucky me.

http://img.photobucket.com/albums/v51/N ... st/HB2.jpg[/pic]

Aughnanure · Post by **Aughnanure** » Tue Apr 04, 2006 3:59 pm

I always knew that there was a reason that I prefered to be an Infantryman

Eoin.

Brian the Brit · Post by **Brian the Brit** » Tue Apr 04, 2006 4:58 pm

Taken from "Guns Australia", October/December 2003 Page 24 "Technical Advice by Nick Harvey"

"Q: Can you tell me why British service rifle barrels are rifled with a left-hand twist rather than a right-hand twist used by the Australian military?
Harold Freedland

A. Back in 1886, the British military found that the rotation of the earth in the northern hemisphere caused a bullet to deviate about 6 inches to the right at 1000 yards. Maximum drift occurred when the shot was fired towards the north east and minimum drift when the shot was at the opposite azimuth. This was in addition to normal drift in the direction of the rifling twist. To counteract this, they decided to use rifling with a lefthand twist which reduced the total drift by about 30 percent. Bullet drift effect due to the rotation of the earth varies inversely according to proximity to the equator and it drifts towards the left below the equator. Hence our military chose to use a right-hand twist."

Since when have armies restricted themselves to fighting wars only in their own hemisphere, I wonder?

I still think it's bollocks. What say you?

Brian

Strangely_Brown · Post by **Strangely_Brown** » Tue Apr 04, 2006 5:12 pm

I can not help feeling the subject would have come up on one of the forums before if there was some truth in the subject.

Off topic again I can remember as a young gunner on some of the bigger American guns we had at the School of Artillery (M107) there was a correction for rotation of the earth, I forget what it was worth at 30,000 kilometres possibly something like a couple of centermetres from memory.

Didn't realise just how many FOO's, FAC's and CP wallahs were on this site.

Brian the Brit · Post by **Brian the Brit** » Tue Apr 04, 2006 5:16 pm

Can you check that range please, Gunner Kelly?

Strangely_Brown · Post by **Strangely_Brown** » Tue Apr 04, 2006 5:30 pm

Sorry!

Too many 0000's.

From memory it had a maximum range of about 33 K, any ex gunners on site remember?

Post by **Niner** » Tue Apr 04, 2006 9:05 pm

Close support guns, like 105's had an effective close support range of around 9000 meters from gun to target. And that was pushing it. Max range was around 13,000 meters, although I don't remember exactly anymore. Heavy guns had a much longer range.

Arty batteries would register every so often with an observer making corrections. This would make some general first round accuracy possible by adjusting for powder lot, atmospheric conditions, and other considerations, probably the rotation of the earth being one of them. But the results were more simple observation than scientific calculation. Just about the same as zeroing a rifle. And... when the next fire mission came with danger close fire and it happened to be in a rain storm... well... all bets were off and it was still first round wp 200 up as the first fire command. And besides that the fire direction came from someone on the ground who only kinda sorta knew where he was within a hundred meters or so, another reason for the white phosphorus round. No gps 35 and more years ago. The rotation of the earth didn't come up as a question.

Ned · Post by **Ned** » Tue Apr 04, 2006 11:50 pm

They all had a planning range and actual range. I was never an artilleryman but the 81mm mortar had a planning range of 4200 metres but with charge 9 and a cup of petrol down the tube you could get around the 5 click mark.Also break the torsion bars on a M113 APCM. The 155 with a rocket assisted round could get the 33 click mark maybe even further I think. memory fades with time, but get me on a tube again and I reckon I could lay on as quick as i did 20 yrs ago, never forget the mechanics !!!

:pirate:

Aughnanure · Post by **Aughnanure** » Thu Apr 06, 2006 1:04 am

I guess I shouldn't get back on topic but...

You can take it as gospel (Eoin 1-4) that Lithgow .303" Lee-Enfields had left hand twist (1in 10) the same as their Indian and British counterparts.

Nick Harvey is a good bloke and really knows his stuff, but even he makes a mistake now and again, witness his statement in his reloading manual,

"Be warned: case heads are not fully supported in 7.5MM Swiss rifles and overloads can be extremely dangerous."

Eoin.

Direction of twist in Enfield barrels?

This is adding to the off topic turn

Here's the article - it wasn't a Poisson d'Avril!

Northern Hemisphere

How many kilometres?