Path: spln!rex!extra.newsguy.com!lotsanews.com!nf3.bellglobal.com!sunqbc.risq.qc.ca!nntp.flash.net!news-out.visi.com!hermes.visi.com!gemini.tycho.net.POSTED!not-for-mail Approved: sci-military-moderated@retro.com Return-Path: news@google.com Delivery-Date: Tue Oct 16 11:30:00 2001 Delivery-Date: Tue, 16 Oct 2001 11:30:00 -0700 for <sci-military-moderated@retro.com>; Tue, 16 Oct 2001 11:29:58 -0700 (PDT) for <sci-military-moderated@moderators.isc.org>; Tue, 16 Oct 2001 14:13:58 -0400 (EDT) for <sci-military-moderated@moderators.isc.org>; Tue, 16 Oct 2001 11:13:27 -0700 for <sci-military-moderated@moderators.isc.org>; Tue, 16 Oct 2001 11:13:27 -0700 for sci-military-moderated@moderators.isc.org; Tue, 16 Oct 2001 11:13:27 -0700 To: sci-military-moderated@moderators.isc.org From: autogun@globalnet.co.uk (Tony Williams) Newsgroups: sci.military.moderated Subject: Re: Smooth bore vs rifled gun barrels on Abrams Date: 16 Oct 2001 11:13:27 -0700 Organization: http://groups.google.com/ Message-ID: <a516ee75.0110161013.4236be39@posting.google.com> References: <3BC9D3BC.48122855@c0.comm> <9qgdpq$7a7@gap.cco.caltech.edu> X-NNTP-Posting-Host: 62.6.74.4 Content-type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Complaints-To: groups-abuse@google.com X-NNTP-Posting-Date: 16 Oct 2001 18:13:27 GMT Content-Length: 1837 Lines: 37 NNTP-Posting-Host: f43dced8.newsreader.tycho.net X-Trace: 1003264242 gemini.tycho.net 327 205.179.181.194 X-Complaints-To: abuse@tycho.net Xref: spln sci.military.moderated:39667 raj@alumnae.caltech.edu (Roger Moore) wrote in message news:<9qgdpq$7a7@gap.cco.caltech.edu>... > "Zonie" <Zonie!@c0.comm> writes: > > >The M1A1 Abrams converted to a smooth bore from a smaller rifled bore. > > >What advantages does a smooth bore give you? > > Most modern anti-tank ammunition is fin stabilized rather than spun. > Discarding sabot ammo is not, IIRC, especially hurt by being spun, but > neither is it helped, while HEAT rounds are definitely hurt by being spun > rapidly. Since those are the main choices for tanks these days (the Brits > still like HESH, but they're pretty much alone in doing so) there's not > much point in using rifling, while a smoothbore has some wear and velocity > advantages. True enough, but so far no-one has explained WHY the Brits prefer a rifled gun. The answer is simple; long range accuracy with HE shells. Fin-stabilised shells (as opposed to APFSDS) are inherently less accurate than spin-stabilised ones. Also, the HESH shells are much more versatile than HEAT, being not only effective against armour but also acting as a general HE round. Tank kills have been recorded at enormous distances using HESH (4 - 5 km IIRC; about double the capability of APFSDS, whether fired from rifled or smoothbore barrels). To sum up, the smoothbore is the optimum choice for medium-range anti-tank work using APFSDS, the rifled barrel is more of a general-purpose weapon. Incidentally, the performance penalty from firing APFSDS from a rifled barrel appears to be very small, judging by the published specs for the 120mm Challenger. Tony Williams Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces" Details on my military gun and ammunition website: http://www.users.globalnet.co.uk/~autogun/index.htm