Ammo for Interarms Mauser
 

The 4" Swiss frame Interarms Mauser Parabellum that I am breaking in is exhibiting all symptoms of being oversprung for SAAMI-spec ammunition, failing to eject intermittently and refusling to lock back after the last round. Which U.S. factory brand of high pressure ammo is best suited for this pistol?

Michael, Is your Parabellum in 7.65 or 9mmP? TH

How many rounds have you put through it? Unless it's really bad, I'd allow 200 rounds as a break in period before I started really worrying about reliability. My standard for a reliable new bought pistol is to ignore the first 200 rounds and tolerate no malfunctions in the second 200.

I'd make an exception in the first 200 rounds if it has obvious problems. I might tolerate one malfunction in the second 200 rounds if it's a for fun pistol as opposed to one for social occasions.

And if there are problems, then you are correct in not overlooking the possibility that the ammo is the problem.

If its a 7.65, the factory ammo will be under loaded. Fiocchi produces the lowest velocity, Winchester the next lowest. I have not run Remington/Peters over the chronograph yet but suspect it is the hottest load if you can find it. You are looking for high velocity, not high pressure. It's a recoil operated action, not a blow back.

If it's a 9 mm the factory ammo will be too short. Try the Wally World Winchester hardball special. It's has the longest OAL of any factory load I know of off hand.

(Really bad is defined by an AMT 380 I had that averaged 2.5 malfunctions per magazine load including such wonders as tossing a loaded cartridge out in front of me.)

</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 Michael Zeleny:
[QB]...is exhibiting all symptoms of being oversprung for SAAMI-spec ammunition, failing to eject intermittently and refusling to lock back after the last round./QB]</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi Mike:

Again, your problem may be too short of an OAL to properly feed from the step-feed magazine of a Luger.

For factory ammo that may just work, I'd try the German ammo made by GECO in 124 grain, or the Czech S&B ammo, again in 124 grain. In American ammo, I'd also try one box of 130 gr. for function.

If the ammo you are now shooting is less than 115 gr., don't expect reliable function in a Luger.

Sieger

oh, so that is why those 85 grainers wouldn't work Sieger!

Years ago, I was playing around, reloading and those 85 grainers would only function about half the time.... and I tried to stretch the bullet up to make OAL :D

Thanks to all for thoughtful replies. The Mauser Parabellum is a 9mm. I would like to count on it for social work. I used two original Mauser magazines that were very tight laterally. The East German 2/1001 milled rework magazine that inspired my hopes of perfect functioning, did not feed at all. I fired around 170 rounds, most of them Axis FMJ, such as 115gr Fiocchi and 124gr Geco, with a few 123gr Hirtenbergers thrown in. The OAL is about as long as it gets. Everything easily stays in the black offhand at the point of aim at 15 meters. The failures to eject were most prevalent, about once midway through every other magazine, with the breech stopped from closing on a half-chambered round by the flipped over fired case. At the end I managed to empty two magazines of Remington Express 9mm +P 115gr JHP that felt a lot more welcome in the toggle action, suggesting a taste for higher pressures.

Dear Mike:

The Geco 124 gr. ammo is loaded hotter than hell, so I'm wondering why it wouldn't kick back your action.

It sounds to me like OAL could be part of your problem. If you can measure them, if they are shorter than 1.173 inch and they are round nose ball, expect feeding problems. The sad thing is that most modern ammo is loaded to 1.169 inch, too short to reliably feed in a Luger.

If you want better function with regular, readily available ammo, consider having your recoil spring changed to one balanced to it.

If you can reload your own, this is the ultimate answer.

Several folks here can help you with your spring questions.

Sieger

</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 Edward Tinker:
<strong>oh, so that is why those 85 grainers wouldn't work Sieger!

Years ago, I was playing around, reloading and those 85 grainers would only function about half the time.... and I tried to stretch the bullet up to make OAL :D </strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Dear Ed:

Yep, 115 and up will provide the momentum needed to unlock that toggle.

Sieger

Michael,

I get malfunctions like you describe when my '36 shooter gets too dirty. When I first got it, I had to clean and carefully lube every 50 rounds. Now that I've put about 700-800 rounds of Wal-Mart Winchester 115 gr ammo through it I can go maybe 250-300 rounds until malfunctions start. It's 100% reliable now when reasonably clean. Guess the gun was never really shot enough to break it in until I got it.

I am a shooter, not a hard core collector. They gotta shoot or out they go.

Hi,

Following the advice of some forum experts, I started using the S&B 115 9mm. Works fine, although the combination of a MecGar and my dutch M11 is somewhat erratic at times. My other (unknown origin) magazine works without problems.

Anyone have the product code for the WalMart 115 gr. winchester? I've found a dealer who can order winchester 9mm, but they have 4 separate product codes to choose from...

Winchester 9mm Luger
115gr. fmj
Target/Range
100rd Value Pack
USA9MMVP

Michael,

I just shot another 50 rounds of Wallyworld Winchester through my '36 Mauser shooter today. I did have one failure to lock open--otherwise perfect function. I use a SS MecGar magazine. It has been about 100 rounds since it was cleaned. Everything went into a 1.5" high by 2.5" wide group. Great gun.

stymie, thanks. Will inform...