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Lugers in .38 Super

Out of curiosity, how hard would it be to convert a 9mm to .38 Super. Other than the bore diameter being a few thousands different. I loaded a standard mag with some supers, they sat a bit more upright. But they did feed properly.
Comments.

Doug,

Does the case rim fit in the breechblock? If not, then it would have to be opened up... IF it does fit the breechblock, then all you would need is a barrel change...

Since the standard OAL is somewhat longer, I doubt that feeding would be very reliable...but you might be willing to live with that..and of course you would have to beef up the recoil spring... I would stay away from hot loads too...

but on the other hand -WHY? what would you gain over 9MM loaded hot?

John Martz has cranked out a dozen or more of his custom Lugers in this caliber, but I think he did his frame stretching magic for the conversion. As to why anyone would attempt such a thing, I would guess it is for the same reason given by people who climb mountains...for the challenge.

I believe the 38 Super is a semi-rimmed cartridge so the rim diameter is greater than the 9 mm Parabellum and the breech face would have to be milled out a bit. One might think of 9 mm Magnum brass trimmed to 38 super length.

My own idea is that AIMCO should be encouraged to produce a Luger chambered in 357 SIG. They once made a tool room job in 10 mm, so there is a bit of background experience. In this case the whole pistol would be scaled up a bit to handle the hotter round.

<blockquote>quote:<hr />Originally posted by Doug G.:
Out of curiosity, how hard would it be to convert a 9mm to .38 Super. Other than the bore diameter being a few thousands different. I loaded a standard mag with some supers, they sat a bit more upright. But they did feed properly.
Comments.<hr /></blockquote>There should be NO difference in bore diameter between 9mm & .38 Super.... both use the same .355" diameter bullets. It would also be easier to have the pistol converted to 9mm Largo or 9x23mm. The case is rimless and the same rim size as the Luger cartridge. 9x21mm would likely work even better.

While the .38 Super cartridge was a good idea, the semi-rim was not. The cartridge headspaced on the rim causing accuracy to suffer badly; mostly due to different thicknesses of rims. Newer .38 Super chambers are set for headspacing on the case mouth and accuracy is generally better than in the older guns.

Doubs,

Why should headspacing on the rim affect accuracy? Given good proper headspacing, I'd assume either type to be equally accurate. In general I've heard more horror stories about bad headspacing with types that head space on the case mouth.

On the other hand, it would be interesting to know why the semi rimmed self loader pistol cartridges were semi rimmed. What's the point? Trickier to get the headspace right when reaming a rimless cartridge chamber?

There are several rimless cases that would be a good canididate for the above project, but I have to agree the bottom line is "Why?" In my opinion a better useless wildcat project would be to neck the 7.65 up to 8 mm. Or my armchair ambition to have a revolver chambered for the 7.65 mm Parabellum.

In addition to lenghtening the mag well and beefing up the recoil spring, when Martz does this conversion, he also changes the toggle ramp part of the frame, so that the toggle opens wider for the 6mm longer case. He also opens up the breech face for the wider semi rimmed 38 Super case. I do have a couple of PO8 breech blocks that he opened for 38 Super or .40 S&W @$75 each. TH

<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.

When Colt origially built the 38 super it head spaced on the rim and was not accurate. Only when the IPSC crowd started using it and changing to head spacing to the case mouth did it become a usable accurate round. If you wanted to strech the receiver and the mags you could convert it to the new rimless cases refered to as the 9 super comp or 9 X 23. No need to open up the breech face when using these cases and they are availble at Star Line and Hornady. anddid

<blockquote>quote:<hr />Originally posted by Hub:
Only when the IPSC crowd started using it and changing to head spacing to the case mouth did it become a usable accurate round.<hr /></blockquote>Hub, thanks for the added information. I came back this morning intending to give credit to the IPSC shooters for the renewed interest in the .38 Super cartridge. The 9x21, 9x23 and .38 Super became more attractive when IPSC ruled that 9mm Luger loaded to Major Class was not safe and therefore not allowed in competitions. At least that's how I recall it.

Doubs,

Yes, you do occasionaly get odd cases like this where something fails to work for reasons having to do with design shortcomings rather than any inherent weakness. I am presently contending with this in 45 Colt, where the SAAMI chamber is oversized to the detriment of accuracy and case life. The oversized chamber is a hangover from the days of black powder when you had to leave room for the fouling to maintain reliable reloading.