Sunday, August 7, 2011

Part 2: Using The Ladder Test - Lee TL358-158-SWC & 358-429 Keith with Unique and 700X

This installment covers the initial test results using the Ladder Test for a Ruger Blackhawk.  A few key truths are made evident and discussed.  I believe the results of this project translate to your 357 Magnum revolver and aren't only for my Ruger.

For the time being, ladder testing and validation using H110 moved onto the back burner.  700X and Unique early results are covered.

700X has proven to be one of the most accurate powders in the Taurus 66, and also the Rossi lever action rifle.  The ladder test for the 358-158-SWC (tumble lube Lee mould, lapped and now dropping 168 grain bullets) going from 2.8 grains to 5.3 grains, in .3 grain increments:

The 700X ladder test for the 358-429 Keith (lapped and dropping 180 grain bullets) ranged from 3.1 to 4.6 grains:

The 358-168-SWC test results didn't look very conclusive to me, so I followed up with some accuracy testing to see what would those results would indicate.  Wow, it wasn't pretty.  Rather than posting picture of horrible groups, here is the bottom line:
  • The Blackhawk won't shoot this bullet accurately with 700X
  • This bullet causes light leading near the forcing cone, with all charges.  It wasn't horrible, but enough to affect accuracy after 50-60 rounds.  Not acceptable
  • The Blackhawk does not shoot either of the 2 best bullets well with 700X.  Proof that bullet / powder combinations don't work equally well in every gun
So what does that say about ladder testing?  Load accuracy is the result I was looking for and all that ladder testing promises to offer.  The results weren't conclusive and when followed up with additional testing, 700X proved to not be accurate.  As much as the other 357's love it, the Ruger doesn't.

The Ladder Test can in fact save time in determining that the gun-bullet-powder combination isn't effective, there was no clear sweet spot because this combination doesn't work.  I think that's a big plus.

  • A note regarding the leading:  It was a small amount of leading, right were the lands start. The area between the cylinder throats and the lands is critical in a revolver.  It's possible that the short 358-158 bullet allows gas to get around the bullet, in this critical area.  Enough to cause this light leading, and the resulting loss in accuracy.  Basically, a form of gas cutting. The leading occurred using Unique as well.  With the longer Keith, there's no leading after 200 rounds.  That's a big difference between the Taurus, that loves this bullet, and the Ruger.

How about the results from the Keith ladder test?  This test indicated a charge of 4.1 to 4.2 to be a sweet spot.  After testing, it wasn't.  There was no leading with this bullet, but it confirmed that the Blackhawk just doesn't like 700X.  At least with 2 of the most proven bullets in other 357's.

Again, the ladder test proved to be helpful.  It suggested a sweet spot that once tested, didn't work out.  It saves time over testing 20 rounds, or more, at each charge weight (my old testing approach).

Before I would have loaded and test 20 rounds at each of the 6 charges, for a total of 120 rounds.  Using the ladder test, I loaded 6 rounds and could have validated it with 20 more, for a total of 26.  I did load and shoot more than that to see if the ladder test missed a sweet spot, it didn't.  So far the ladder test is looking promising, even in a revolver and even at 25 yards.

But can it find a validate sweet spot?  Here is the Unique ladder test with charges from 5.0 to 5.9.  Not a huge range, but I wanted to give it a try.

Now we are talking!  The sweet spot is clearly between loads 2 & 3.  Here is a group using 5.4 grains:

Please don't let my limited photographic skills mess up the effectiveness of these results.  The ladder tests are on a big bullseye target.  This test is on a target less than 1/2 the size.  This group (excluding the shot I pulled) is a .668 group.  Yeah, that's what I'm looking for!  A sub 1 inch group, rested, at 25 yards using iron sights.  That is a further indication that ladder testing (revolver, at 25 yards) WORKS.

I was able further validate, this is one sweet accurate load. BUT!  This bullet still has the leading problem.  That tells me it's not the powder as much as the bullet and the Blackhawk not working together.  Testing with the H110 will either be strike three, or may work.  It remains to be seen.

Conclusion:  Early results of ladder test are positive.  It saves reloading and range time by reducing the number of rounds needed to find a sweet spot.  In my tests, the inconclusive results proved that there was not a sweet spot, another ladder result let me quickly determine that 700X didn't work with the Keith either.  Then the third test produced a super accurate load, with a minimal number of rounds loaded and shot.  That's very impressive.

This is extremely useful since bullet moulds and powders don't always translate from revolver to revolver, or if you need to work up a new bullet & powder combination for your revolver.  Both 700X and the 358-158 that work so well well in other revolvers barely even group in the Blackhawk.  Unique in the Blackhawk is working out very well, even though it didn't give the best results in the Taurus. 
  • A .668 inch group is the best I've ever shot with iron sights.  That's exciting!
Part 3 is already in the works.

Shoot tight groups and enjoy your 357 Magnum.  The most versatile and fun caliber to cast and handload, in my opinion of course.

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