Need help with .30 bullet selection

[CptCurl]

Originally Posted by Sieger

Curl,

The two jams you describe above sound like the typical, annoying "Luger Jam".

Cartridge O.A.L. is critical for positive action function. Your tests for proper O.A.L. should be done before you go the range. For a good explanation of how to determine proper O.A.L., for a new bullet type, please see my thread on "Determining Proper Cartridge O.A.L." in this section of the site. I bet your O.A.L. is too short, but you won't know until you have gone through the pre-firing development stage, then the range test. The original O.A.L.s, of both the 9mm and 7.65mm DWM truncated cone bullets, were right at 1.14 inches (29mm). I have noted that the wider the "flat" on the nose of the bullet, the shorter the proper O.A.L. for proper function. Remembering that the original DWM "flat" was 4mm, you might want to measure the "flat" on your subject bullet. If I were testing, I'd start at 1.15 inches and work down .01 inch at a time until I found perfect function.

Once you have determined the proper O.A.L., for the bullet you are testing, then you are free to move on to the charge development stage. Again, I'd start at about 4.8 grains or so and work up 0.1 of a grain, at a time, until you get perfect action function and accuracy. Accuracy, for me, is three out of three touching at 25 yards, shot off of sand bags.

When the action starts working (with proper hold open) and the groups start tightening, then you are in the range to develop a great load.

I'd be interested in seeing the necks of your fired cases. Do the necks show any pressure signs; for instance, chamber milling marks engraved into the brass?

By the way, your initial load shot through eight one gallon milk jugs?!?. If you would test again, after you are comfortable with your load, I'd really be interested in seeing just how many jugs it takes to actually stop your bullet.

Sieger

Sieger,

I took your advice and lengthened my OAL rather than shorten it. I loaded a batch with the bullet seated for exactly 29mm OAL. I changed nothing else.

The first issue I faced was with the magazine that accompanies my DWM 1920 Commercial "shooter". It's an after-market magazine, brand unknown. Dimensionally it is too short (front to back) to accommodate rounds at 29mm OAL. I can place seven rounds of these longer rounds in this magazine, but it will not accept the eighth round. So I tried an original DWM magazine. They fit perfectly. Also with a WW2 military magazine. Therefore, I did my shooting this afternoon using these two magazines and not the after-market one.

The pistol functioned flawlessly over two full magazines.

Accuracy was somewhat disappointing, but I must confess my less than stellar ability with the Luger's spongy trigger pull.

You were certainly spot-on as to OAL.

More later.

Curl