38 Super headspace is making my head spin

All of the literature seems to blame the "accuracy" problems early in this cartridges' life, on the fact that chambers were cut to headspace on the semi-rim.  Doesn't the 38 Special, one of the most accurate cartridges we have,  headspace on the rim?  And wouldn't you think that headspacing on the rim actually gives you MORE precise positioning of the bullet relative to the beginning of the rifling, since we no longer have to worry about case length?  Why am I thinking that the Super should be, and have always been, a more accurate cartridge than anything that headspaces on the case mouth?

The semi rim is too small for reliable headspacing so we intentionally cut the chambers to headspace on the mouth. The 32acp is also a semi rimmed case and we do the same thing there. The 38 special rim is huge by comparison.

Im sure all factory supers today headspace off the case mouth. Think it was BarSto that initially made the change

The Super Comp brass which is all I use is pretty much rimless.

We should thank the action pistol community for bringing us the improved barreling of the .38 Super. They wanted more power than 9mm and more capacity than a .45 acp, but more accuracy than the then .38 Supers. I don't know who came up with the idea, but as was mentioned I am pretty sure it was Irving Stone at Bar-Sto who first produced barrels in .38 Super head spacing off the neck, instead of the rim. Early 1980s era.

Does anyone know for sure, if the most accurate .38 Special semi-autos headspace off the neck? Should they? Interesting....

I don’t think it was Irving Stone alone who made the switch.  Like most things it was likely a small set of individuals who came up with the idea.  Irving Stone likely made it more readily available.

As for the 38 match barrels?  I dunno.  They kinda lost favor thru the 80s and the concept likely didn’t get passed tru.  The rim really does give adequate headspace control even with just a partial engagement like a hooded barrel.  

Neither of these cartridges have the headspace dimensions on the case mouth codified in the SAAMI chamber drawings.

Allgoodhits wrote:We should thank the action pistol community for bringing us the improved barreling of the .38 Super. They wanted more power than 9mm and more capacity than a .45 acp, but more accuracy than the then .38 Supers. I don't know who came up with the idea, but as was mentioned I am pretty sure it was Irving Stone at Bar-Sto who first produced barrels in .38 Super head spacing off the neck, instead of the rim. Early 1980s era.

Does anyone know for sure, if the most accurate .38 Special semi-autos headspace off the neck? Should they? Interesting....

I don’t work on or shoot M52 .38 specials, so they are not included. They also in my time as a serious BE competitor did not provide the accuracy to shoot and win matches against our countries best shooters.
All the 1911 .38 special conversions I have seen have always headspaced off the rim and the end of the chamber varies from 0.020-0.030” beyond the case mouth. I think that is excessive but they still shoot well; 1.5” ish at 50 yds.
Jon

The following is from this article:  http://www.shootingtimes.com/editorial/super-accurate-38-super-loads/326242


"The .38 Super is a very accurate cartridge, something not so well known to many shooters just a few decades ago. In fact, many Colt Super 38 1911 pistols had a reputation for poor accuracy. The problem was traced to excessive headspace. The chambers were cut too deep because the round was expected to headspace on the semi-rim. The problem was that the semi-rim could slide past the cutout in the barrel’s hood, allowing the round to slip too far forward and essentially headspace off the extractor. Accuracy suffered.

John Rollins and Richard Shockley identified the problem and sleeved the barrel chamber so the cartridge headspaced off the case mouth. They described this in an article in the June 1961 issue of American Rifleman. Once properly headspaced, accuracy improved."