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Doubs · 12-06-2003, 01:53 AM

<blockquote>quote:<hr />Originally posted by unspellable:
Doubs, Why should headspacing on the rim affect accuracy?<hr /></blockquote>According to the sources I've read, the rim thickness of the cases varied enough to affect accuracy. The original Colt .38 Super came out in 1929 and it earned a reputation for mediocre accuracy at best. Production of the .38 Super was dropped by Colt for a number of years. The problem reportedly was caused by rim thickness variations and in recent years it has become standard practice to cut .38 Super chambers to head space on the mouth of the cartridge. The following is a direct quote from the NRA book "Handloading", pg. 244:

"...the .38 Super is a semi-rimless cartridge, intended to headspace on the narrow rim, against a surface at the breech face of the barrel. Owing to the very narrow rim, and to diametral tolerances allowed for cartridges and chambers, there are instances in which the rim does not firmly engage the surface intended to support it, and headspace control is therefore erratic. Probably for this reason, ignition may also be erratic, and accuracy can be disappointing. The .38 Super Auto has never achieved a reputation for accuracy as a target arm, though it is mechanically nearly identical to the Colt .45 Automatic which is highly regarded among target shooters."

The book was published in 1981 and I believe that more recent guns chambered for the cartridge to headspace on the cartridge mouth are much more accurate than earlier pistols.

12-06-2003, 01:53 AM	#9
Doubs User Join Date: Jun 2002 Location: Byron, Georgia Posts: 1,736 Thanks: 819 Thanked 1,769 Times in 586 Posts	</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by unspellable: <strong>Doubs, Why should headspacing on the rim affect accuracy?</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">According to the sources I've read, the rim thickness of the cases varied enough to affect accuracy. The original Colt .38 Super came out in 1929 and it earned a reputation for mediocre accuracy at best. Production of the .38 Super was dropped by Colt for a number of years. The problem reportedly was caused by rim thickness variations and in recent years it has become standard practice to cut .38 Super chambers to head space on the mouth of the cartridge. The following is a direct quote from the NRA book "Handloading", pg. 244: "...the .38 Super is a semi-rimless cartridge, intended to headspace on the narrow rim, against a surface at the breech face of the barrel. Owing to the very narrow rim, and to diametral tolerances allowed for cartridges and chambers, there are instances in which the rim does not firmly engage the surface intended to support it, and headspace control is therefore erratic. Probably for this reason, ignition may also be erratic, and accuracy can be disappointing. The .38 Super Auto has never achieved a reputation for accuracy as a target arm, though it is mechanically nearly identical to the Colt .45 Automatic which is highly regarded among target shooters." The book was published in 1981 and I believe that more recent guns chambered for the cartridge to headspace on the cartridge mouth are much more accurate than earlier pistols.