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nok · 03-05-2014, 12:09 AM

I have a circa 1975 Interarms Mauser 9mm luger, 4" barrel. It was basically unfired when I obtained it. Pretty, yes. Reliable, no way. I don't think it would make it through an entire magazine for the first few years I owned it. I didn't get to shoot all that much, but recently an indoor range opened (to the public). This gave me a much needed opportunity to chase down some variables. I can tell you this: At the range tonight, out of 100 rounds fired, I had one jam. Last time out, zero jams.
I'm only posting this in case anyone else with the same gun is as frustrated as I was. Firstly, most of the conventional wisdom turned up in my research was exactly wrong. This particular firearm DOES NOT like "hot loads". It also likes shorter COAL. I had bought some UMC 9mm FMJ at a gun show, and it performed better than anything else I had ever used. These cartridges are visibly shorter than any other commercial ammo I checked. I now load all my Luger rounds at 1.121". Secondly, I changed magazine springs. I still think a more powerful spring would help, but all I could find were Wolff springs @+10%. I'm thinking of winding some springs of my own since I can easily hand-load a Wolff-equipped mag even without the loading tool (others say they just cannot get that eighth round into the mag). Thirdly, I changed extractors. Repros are available from Numrich, along with much stronger extractor springs. By the time I had made these changes, I think the gun was about 75% reliable. Better, but still frustrating.
The final piece of the puzzle was changing to a different powder. I had some success after doing trials with Unique, but nothing I would consider definitive. It seemed from my reading that original luger rounds were loaded with a slow-ish powder. The answer to that turned out to be Winchester AutoComp. After fine-tuning the charge, I have finally been able to fully enjoy this Luger. I love the gun and succeeding in making it reliable has made it my favorite at the range.
My reloading recipe for this pistol is:
Remington FMJ 115 gr. bullets
Winchester Small Pistol primers (although I would try CCI500's)
5.4 gns. of AutoComp powder (gives about 1100FPS)
Cartridge over all length=1.121"

Hope this helps somebody or gives them a couple ideas if they're having trouble with their own Luger, whatever the vintage and make.

03-05-2014, 12:09 AM	#1
nok New User Join Date: Apr 2013 Posts: 1 Thanks: 0 Thanked 1 Time in 1 Post	Interarms 9mm luger now fully reliable I have a circa 1975 Interarms Mauser 9mm luger, 4" barrel. It was basically unfired when I obtained it. Pretty, yes. Reliable, no way. I don't think it would make it through an entire magazine for the first few years I owned it. I didn't get to shoot all that much, but recently an indoor range opened (to the public). This gave me a much needed opportunity to chase down some variables. I can tell you this: At the range tonight, out of 100 rounds fired, I had one jam. Last time out, zero jams. I'm only posting this in case anyone else with the same gun is as frustrated as I was. Firstly, most of the conventional wisdom turned up in my research was exactly wrong. This particular firearm DOES NOT like "hot loads". It also likes shorter COAL. I had bought some UMC 9mm FMJ at a gun show, and it performed better than anything else I had ever used. These cartridges are visibly shorter than any other commercial ammo I checked. I now load all my Luger rounds at 1.121". Secondly, I changed magazine springs. I still think a more powerful spring would help, but all I could find were Wolff springs @+10%. I'm thinking of winding some springs of my own since I can easily hand-load a Wolff-equipped mag even without the loading tool (others say they just cannot get that eighth round into the mag). Thirdly, I changed extractors. Repros are available from Numrich, along with much stronger extractor springs. By the time I had made these changes, I think the gun was about 75% reliable. Better, but still frustrating. The final piece of the puzzle was changing to a different powder. I had some success after doing trials with Unique, but nothing I would consider definitive. It seemed from my reading that original luger rounds were loaded with a slow-ish powder. The answer to that turned out to be Winchester AutoComp. After fine-tuning the charge, I have finally been able to fully enjoy this Luger. I love the gun and succeeding in making it reliable has made it my favorite at the range. My reloading recipe for this pistol is: Remington FMJ 115 gr. bullets Winchester Small Pistol primers (although I would try CCI500's) 5.4 gns. of AutoComp powder (gives about 1100FPS) Cartridge over all length=1.121" Hope this helps somebody or gives them a couple ideas if they're having trouble with their own Luger, whatever the vintage and make.