"Original" Colt 1911s chambered in .38AMU

First topic message reminder :

This bit of history goes way back.

Back in the 50s the AMU took a 1911 in .38 Super, reamed out the chamber deep enough for a rimless .38spl (that the AMU made on a lathe out of .38spl brass) case and created a new caliber known as .38 AMU to create a more competitive centerfire gun.

I'm hoping that one of you guys was around back then. There are guys trying to collect the old Colt .38 AMU bullseye guns and we are trying to figure out if there were any of these guns produced in the Colt factory or if they were all converted by armorers and gunsmiths in the aftermarket.

Let me know what you guys remember about those .38 AMUs.

A thousand cartridges should do 

Greetings,

The 38 AMU is not rimless, it is a semi-rim like the 38 super.

The 38 AMU barrels were chambered such that the head space was controlled by the rim, not the mouth like some 38 Super offerings.

Cheers,

Dave

In the book "U.S. Military Match and Marksmanship Automatic Pistols" authored by Bill Jenkins there is 7 pages with pictures about the 38AMU. Any questions or details one may ask are covered.
Tom Ginovsky

I just purchased a Colt .38 AMU kit which has not been altered to .38 S&W Special.  Can anyone tell me if these kits were only intended to be used on a .38 Super Auto frame or if they can be used on a .45 frame.  Also, is there any difference between the two frames?  Thanks in advance, Dick

You can use frame with 45 slide. Need to change ejector. Feed ramp may need to be altered for 45 to feed correctly. 
Jon

Meant to ask.....does serial number have '-H' suffix?
Jon

Greetings,

Found this on the European CIP website.

http://www.cip-bobp.org/homologation/uploads/tdcc/tab-iv/tabivcal-en-page59.pdf

No dates of original origin; but, the only dimensioned drawing I have ever seen for this interesting cartridge.

Yes, it is Metric. So, get your calculators out. Or, divide by 25.4 to get the inch equivalent.

Cheers,

Dave

Thanks, Dave.  I appreciate the input.  rdc

Tom's reference to the Jenkins book is worth investigating.  It is a great book!  If you're at all interested in the pistols from the Golden Age of Bullseye, you will probably really enjoy the Jenkins book.... (not a dot sight to be seen anywhere).  I suspect it is recently out of print, so prices will only go up if you want a copy.  Amazon used to sell it for about $50.  
Besides the chapter on the 38 AMU, along with all the contemporaneous 38 special WC conversions, there is a lot on the origins of the S&W 52. 
Lots on all the 22s of the time, gunmithing (particularly from the angle of military armorers and marksmanship units), the old 45 Trophy and Award pistols, etc.

Dave's link to the CIP page is very helpful ... and revealing!  Anybody catch the chamber diagram below the cartridge diagram?  If so, you may notice that the diagram shows one of the variations for this cartridge that uses a long throat before the full rifling.  I had a 1959 Clark 38 conversion that had a very similar arrangement.  I talked the Jim Jr about this at one point.  He told me it was to simulate a revolver forcing cone.  I asked him why that would have been important.  He said (paraphrasing) "It was just something they tried back then.  It doesn't help much with anything so we stopped doing it"  My theory is that it was intended to soften the recoil a little bit in much the same way that it is used with competition shotguns.  That Clark did seem to shoot just a little softer than my Giles 38.  But, my Giles is more accurate!

Best Regards,
Jim

Thanks to Jon I scrounged around in my junk box, found a .38 Super ejector, installed it my my .45 frame, and everything works perfectly!  Feeds, extracts, ejects powderless rounds.  Haven't had a chance to shoot it, because we have 2 inches of snow over ice and all Portland, OR is at a standstill!
If anyone still wants a picture of the Colt roll marked slide, contact me and I'll send one. rdc