Saturday, August 13, 2011

Part 3: Using The Ladder Test - 700X Result, Keith and Unique Final Result

First the mould & bullet used in this Ladder Test:  The 358-429 mould from NOE is lapped and now it drops 178 grain bullets.  I round it to 180 and use those recipes.  Since the actual bullet weight is lighter, it's safe.  Working the other way can cause unsafe pressures, so don't use recipes for a lighter bullet.

A recap of Part 2 results:  The 5.4 charge of Unique under the lapped TL-358-158 has proven to be extremely accurate.  The leading problem reported in Part 2 has been completely solved.  Look for an upcoming post "Extreme Alox" to see how.  Ladder tests with a 357 revolver (a 6.5 inch Blackhawk in this case) is producing accurate loads.  This continues to be a great surprise.

Now for the 180 grain Keith.  For a description of the test approach please refer to Part 1 and Part 2.

This time there are 2 sweet spots.  The pairing of shots 1 & 2 is the first, then 3 & 4 is the second.  That suggest 5.1 grains of Unique and also 5.7 grains of Unique.

At this point, I know this bullet and the TL358-158 are the 2 most accurate moulds for a 357 magnum, and that the Ladder test produced a great load for the  TL358.  So I decided to shoot the 2 loads from this ladder off-hand, 25 yards with the open iron sights and unsupported in any way.  I fully expect that off a rest they will group well, just like the TL358.

First the 5.1 charge of Unique.  This is looks to me like another great load:

The 5.7 load is just a bit bigger, but still very respectable:

Not bad!

A review of the progress so far:
  1. 700X didn't produce a good ladder using the Blackhawk.  Verfied later on, this combination isn't accurate.  The 700X and the Taurus 66 357 is the most accurate combination, with that revolver.  The variation of what works in one revolver vs another is quite large.  So don't get frustrated is one of the "proven" recipes doesn't work in yours, try some other powders and you'll find one.
  2. The TL358-158 ladder with Unique produced a charge of 5.4 (1 sweet spot).  It checked out to be incredibly accurate.  Producing a best group, rested and iron sights, of .668 inches. That's awesome.
  3. The Keith ladder with Unique produced 2 charges (2 sweet spots).  A charge of 5.1 and also a charge of 5.7.  They are both excellent, with the 5.1 load having the slight edge.  One off-hand test isn't conclusive in my book.  But that is the result for this test.
  4. With the leading of the TL358-158 resolved, it just edges out the Keith for accuracy, making it the preferred bullet for 357 magnums.

Coming up next, test results for H110 and the TL358-158.  I plan to try all these loads out in the Rossi 20 inch M92 Lever action rifle.  Oh, the Extreme Alox solution will be laid out in detail too.  Without that, the single most accurate bullet would loose accuracy in 40 rounds.  That would make it unusable.

But it is resolved, the Blackhawk and the TL358-158 are now an awesome combination.  If you have similar problems with a bullet leading right at the start of the lands (rifling) maybe Extreme Alox will solve your problem.

At this point, the Ladder Test certainly work in a longer barrel 357.  Give it a try to develop your most accurate loads. 

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