Cast bullets for Mauser Parabellum

[RAY1946]

Recently I purchased a used Luger, this being a Mauser Parabellum in 9mm with a 6" barrel. I decided recently to begin reloading for this pistol. Yesterday I slugged the barrel and found the groove diameter to be a whopping .3585! Is there enough room in the chamber for a bullet this large?
I have seen many old pictures of Lugers with what appeared to be a truncated bullet of I guess WWI design. Is this a good design for the Luger? Lyman has a mold which seems to duplicate this design;356402.
I am new and would like to say thank you to everyone. This is a really cool site with lots of great info!....................Ray

[Sieger]

Originally Posted by RAY1946

Recently I purchased a used Luger, this being a Mauser Parabellum in 9mm with a 6" barrel. I decided recently to begin reloading for this pistol. Yesterday I slugged the barrel and found the groove diameter to be a whopping .3585! Is there enough room in the chamber for a bullet this large?
I have seen many old pictures of Lugers with what appeared to be a truncated bullet of I guess WWI design. Is this a good design for the Luger? Lyman has a mold which seems to duplicate this design;356402.
I am new and would like to say thank you to everyone. This is a really cool site with lots of great info!....................Ray

Hi

The original DWM 9mm groove diameter was 9.1 or 3.58, so your Interarms Mauser would appear to be in the same neighborhood.

The truncated cone bullet types work best in a Luger if the OAL is held to the original DWM standard of 29mm. Yes, I know that part of the lube groove will be exposed, but so what.

I perfer the 124 gr. RCBS Lead Truncated Cone 9mm bullet, because it is more accurate in my various Lugers.

As to your specific question regarding bullet diameter, perhaps the Interarms' newer design chamber will take a 3.58 bullet (because it has no "step" as the original DWM chamber has) but an original DWM chamber will take only a bullet of about .3565, so proceed with extreme caution when experimenting with larger bullets in your Interarms Luger

The Luger will shoot very accurately with 3.56 diameter lead 124 gr. RCBS Truncted Cone bullets (seven touching at 25 yards) with no problem at all!!

To save you weeks of effort, Accurate No 5 is the best powder I have found for this bullet. The accuracy load will be at about 1,070 fps or so, closely matching the original DWM military load.

Search my name and you will find a comprehensive post on the RCBS 124 gr. TC lead bullet and Accurate No5 powder.

Sieger

[RAY1946]

Thanks very much for the loading info! I was thinking along the lines of 4756 or Blue Dot myself, but I will definately give the Accurate #5 a try. I assume your data was established with a 4" barrel, do you Know the approximate groove diameter of your Luger?
I have been toying with the idea of loading one of the 147 gr. bullets. Lyman and RCBS both offer a mold in that size. I would only have to make about 1095 or so to make "Major" in the IDPA league. What a hoot! A 110 year old pistol design competing with the latest and greatest..................................

[Sieger]

Originally Posted by RAY1946

Thanks very much for the loading info! I was thinking along the lines of 4756 or Blue Dot myself, but I will definately give the Accurate #5 a try. I assume your data was established with a 4" barrel, do you Know the approximate groove diameter of your Luger?
I have been toying with the idea of loading one of the 147 gr. bullets. Lyman and RCBS both offer a mold in that size. I would only have to make about 1095 or so to make "Major" in the IDPA league. What a hoot! A 110 year old pistol design competing with the latest and greatest..................................

Hi:

SR 4756 and Power Pistol are the best I have found with 124 gr. FMJ bullets, but only marginal with lead. Search my name and "Good 9mm load in 4 inch barrel" and you will find my specific loads and results.

The Luger was "timed" for 123 gr. FMJTC bullets, so don't expect it to work properly with the heavier bullets. Mine will bearly get by with 130 grs.

Start low and work up until the action will barely work. Keep adding powder until it action outruns the magazine spring. Somewhere between those two extremes, you will find your accuracy load.

Sieger

[RAY1946]

Thanks so much. I will go very slowly..........................

[RAY1946]

Would you happen to remember the "as-cast" diameter of the RCBS 124 gr. bullet? Thanks again,..........Ray

[Sieger]

RAY1946:

Here are some answers to a few of your questions above.

Groove diameters are very standard on Lugers. My 1917 DWM and 1941 Mauser are both in spec. at 9.1mm or .358 inches.

Because I have "vintage year" Lugers, the chambers are stepped. When you look at a fired casing, you will see this little step. This was designed into the chamber to aid in sealing the case to the chamber wall upon firing.

I bought 10,000 of the RCBS 124 gr TC at an estate sale (back in the day) on ebay. They were dirt cheap and were a real quality casting out of what appears to be linotype. The diameter is at .356 and they are lubed with the standard NRA formula of 50/50 beeswax and alox. The key to an accurate bullet with these (as well as most cast bullets) are square and true bases.

Please let me know how you are progressing.

Sieger