Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!uakari.primate.wisc.edu!aplcen!boingo.med.jhu.edu!haven.umd.edu!mimsy!falstaff.mae.cwru.edu
From: gmk@falstaff.mae.cwru.edu (Geoff Kotzar)
Newsgroups: rec.guns
Subject: Re: Downloading Centerfire rounds
Message-ID: <35651@mimsy.umd.edu>
Date: 14 Jun 91 20:05:29 GMT
Sender: magnum@mimsy.umd.edu
Organization: Case Western Reserve University
Lines: 36
Approved: gun-control@cs.umd.edu

In article <35613@mimsy.umd.edu> uunet!clodii.columbiasc.NCR.COM!keith@cs.UMD.EDU writes:
#Hello,
#   I am curious about what would happen if I were to download a .270cal
#round from my normal 50 grns. to say...about 30 grns. Would this be a
#dangerous thing to do. I shoot 130 grn bullets, BTW. Would the cup 
#pressure go up or down?  Could it possibly damage a rifle?   What about
#the sound level? Would it be significantly lower or just a little lower?
#I am just wondering about this since a friend and I were talking about
#it and we could not come with a good answer. Thanks for any answers.
#
#                                                   Keith M. Boyd
#
#
# 
#---
#| Keith M. Boyd  (NCR E&M Cola.) |  Nothing could be fina' than huntin' and  |
#| 3325 Platt Springs Rd.  _______|  fishin' in South Carolina!  -Me-         |
#| West Cola., S.C. 29170 | Std Disclaimers | keith@clodII.columbiasc.NCR.COM |
#| ph: 803-791-6419  |   From uunet: !uunet!ncrcom!ncrcae!sauron!clodII!keith |

Keith you don't state which powder you are using at present and this is VERY
important. Some powders do not take kindly to reduced loads where loading
density drops below something around 85%; the critical powders are classed
as slow or very slow like 4831 or 7828 from DuPont or 4831, 570, or 870 from
Hodgdon. These are not the only ones; there are several others from all the
powder suppliers. Reduced loads from this class of powders have been known
to produce very dangerous pressure excursions that have wrecked rifles. The
medium burning rate powders like 3031, 4064, 4320 from DuPont, Reloader Nos.
7 and 12 from Hercules and similar powders are better suited to your needs.
I think you need to consult either the Lyman manual or the Speer #11 manual.
I think Speer lists reduced loads using DuPont SR 4759 and you could use
the Lyman data for their cast bullets if you were cautious. Remember that
cast bullets tend to produce lower pressures than jacketed bullets of the
same weight in rifles. The starting loads should all transfer without any
problems though; the maximum loads would be different and you would have
to approach them cautiously.                           Geoff Kotzar