Friday, November 18, 2011

The Affect of a Nose Punch on Accuracy - 358-477 Lyman & 358-429 Keith

The Lyman 358-477 is one of the most accurate moulds for my 357 6.5 inch Blackhawk.  For my 357 20" Rossi lever action carbine the 358-477 bullets won't even group at this point.  That just doesn't seem right,  Thinking through the different accuracy tests ant the results (over the past several years and tens of thousands of bullets), I knew this bullet shot best when sized in a custom Lee sizer and tumble lubed.  The Lyman 450 sizer produces bullets that perform almost as well in the Blackhawk, but both lube approaches just failed in the Rossi.

  • I decided to try some tests with different nose-punches, to see if the 358-477 would at least group out of the Rossi.

  • If it worked, I would then run the same test on 358-429 bullets from my new Mountain Mold (see prior posts for more details).

The primary rationale for a nose punch test is that the nose first sizing of the Lee die pumps out "well-centered and square" bullets more often than the Lyman.  Could a loose fitting nose punch in the Lyman cause the bullets to be less accurate?  It's an easy enough test.  Here's the lineup of nose punches with a 358-477:

The flat punch is my standard, it is widely accepted as affective so it made sense to use it.  The deep fit / snug fit middle punch came with a NOE mould.  It also makes sense to give it test and see if there's any improvement in the Rossi.  The RCBS sits in between, but is loose fitting with not much more support than the flat punch.  I included here as a visual reference to show just how deep and snug the test punch is.

I loaded up test loads using 5.4 grains of Unique, using the deep seating NOE punch and headed to the range.  Using the same 2X scope as before, I didn't expect much.  This exact same load was a dissapointment every time I shot it in the Rossi.  So how did it do?  Here are the two best groups, the single flyer in each is shooter induced (sorry about that, I'm only human after all... with no Ransom Rest):

So much for low expectations.  The bottom 4 shot single hole (above the dime, excluding the fifth flyer) measure .190 inches, center to center.  That is the single best group I've ever shot.  Ever.

A quick recap: the 358-477, when sized with the Lyman & a loose nose punch, or the Lee, doesn't group from the Rossi lever action.  There is no before picture, so just think "swiss cheese" and randomly placed holes.  I change the punch to a deep fit / snug fit punch to see what happens.  This bullet goes from zero to hero, unseating the Lee TL 358-158-SWC as the most accurate in the Rossi. WOW!

  • The improvement comes from the bullet being centered while running through the sizer, and being very square and straight as it's sized. 

It's time for the next step, how would this work with the beautiful 180 grain, 358-429 Keith bullets cast with my new custom Mountain Mold.  First, the punch lineup:

The flat punch produces good results with this large meplat bullet, with groups less than 1 inch, at 25 yards & off a rest.  How does the deep fit / snug fit NOE punch affect accuracy. 

These are two different loads. On top is a 5 shot group with13.5 grains of H110.  Very impressive, the real story is the bottom .  It's a 4 shot group (I ran out of test bullets) and my very first revolver group less than .5 inch.  That's pretty special in my book, rarified air IMHO.  It is now the number one most accurate bullet and load, measuring .380 inches, center to center.  WOW AGAIN!

These are spectacular results.  The problem is, my one NOE custom nose punch isn't very helpful to you or anyone else.  It doesn't help me either, with new bullet besigns in the future that need a different size punch.

Luckily, I recently came across Keith Benedict and his unique nose punches.  I've just order 4 for future use.  He offers standard nose punches for a many calibers.  What's so different about his "open" design punch:

They are open so then can be filled with epoxy, or hot glue, and then form fitted to a specific bullet.  That gives a deep fit / firm fit, every time, for any bullet.  If the standard nose punch doesn't quite meet your needs, you can order one custom sized one.

I'm not connected with Keith or his busness.  This is the best solution I've found and need to pass the info along.  You can contact him directly at and he will provide all the information needed.  Including instructions.  If you have a loose fitting nose punch, it may work with epoxy or hot glue, give it a try with what you have.

Either way, taking advantage of a deep fit / snug fit nose punch for maximum accuracy makes good sense.

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