Saturday, November 5, 2011

Mountain Molds Custom 3 Cavity SWC, 358-429 Keith Style

For folks that can't seem to get a 358-429 mould that drops full diameter bullets, here is one great solution.

The last couple of Lyman 358-429's that I bought cast .356-.357 bullets.  Too small to be lapped, especially since they are made of a steel/lead material.  It's too difficult to lap them to .3604 or so, which my guns like sized to .360.

My NOE mould 5 cavity is awesome, but it's only run once a year so you can't order one right now!  There are a few places that can help you out.  Mountain Molds is one of the most unique, with an online design tool.  There are ton of options and measurements that can be changed to make the mold you want.  If the tool can draw it, Mountain Molds can make it.

My new custom 358-429 shoots as great as bullets cast from the NOE and Lyman moulds.  It's one of the top bullets, one of the most accurate and it loves magnum full-house loads.  It is 100% of everything I had hoped for and expected. I did tweak it for a wider meplat, it's a beefed up Keith! 

Before I get to the details, here's a quick look at the top 3 designs that I've found:

A quick review of these great bullets, from left to right:
  1. Lyman 358-477:  The 150 grain mould came already dropping nicely sized bullets.  To get exactly  the size I want, with my soft alloy, took some minor lapping.  With the softer, and also heavier alloy, it drops 4 160 grain bullets.  I shoot a bunch of these every month.
  2. The Lee TL-358-158-SWC  was easier to lap, since it's aluminum, unlike the steel/lead construction of the Lyman.  This now drops at 168 grains, with the soft & heavy alloy.  The Ruger Blackhawk leads at the lands, unless it gets a heavy dose of Liquid Alox.  It's incredibly accurate.
  3. The last two are both 358-429 bullets.  I didn't have a NOE handy for this picture, because I shot all that I had on hand!
    1. This is the Lyman bullet.  It's a little longer than the NOE, but they are similar.  I used this as the model for my custom Mountain Mold.
    2. This is the bullet from the Mountain Mold.  I wanted a little bigger meplat, specified it using the online tool, and it's right on the money.  It fits the Blackhawk really well, and even cycles in a Rossi Lever Action.  A few more thousanths and it probably wouldn't. You can decide how big you want your meplat.  The orignal Keith was (I believe) .250, this one is also .250.
How do you design your own mould

 Go to Mountain Molds website, and select 35/9mm in the drop down.  The measurements that I used are in this screenshot:

Click on the image to get a full size version, use this for input if you are interested.

It takes some learning but in no time you will be used to the interface.  It's a lot of fun and very easy considering that you are actually designing a bullet mould.

Let me say, this mould is awesome.  Mountain Molds will cut either one, two or three cavity moulds.  Check out the absolutely wonderful sprue plate.  If you enjoy casting as much as I do, it's easy to get excited over the Mountain Mold design.  It's thick, it cuts great and the recessed holes making casting a breeze.  I can cast more bullets with this 3 cavity than most other 4 cavity moulds.

What does a Mountain Mold look like (after casting about 10lbs of bullets):

The RCBS handles fit it, or Lee handles fit as well.  It's easy to cut the sprue, and the bullets just drop out of this mould.

Nice looking vent lines and a big block help make this cast so well.  Note the block size in the design tool screen shot above.

Attention to detail is evident in the alignment pins, and the overall look and feel,  This mould is a joy to cast with.  Now you can get any bullet you want, without having to waiting for group buys.  Modeling a design after a known bullet can get you started quickly.

One of the more important decisions is the diameter.  You must decide if you want the specified diameter to be the maximum or minimum, or in the middle of the tolerances.  I choose for .360 to be the minimum.  Since I size and lube, and my guns love fat .360 diameter bullets, this works.

I'll be working up additional design specs in the near future, stay tuned for those results.

At the beginning, I was concerned that the bullets from my custom mould would not be as accurate as I demand and expect.  After all, testing thousand of rounds, testing endless alloys, unending moulds, lapping, sizing, lubes and alloy temps, it all resulted in a finely tuned set of a few excellent moulds.  

Not to worry.  The design is close enough to the model design, which is proven.  Then adjusted for the diameter my guns want, with my alloy.  It surpasses the accuracy and performance of the others, to make it into the top three bullet moulds.  Gotta love it!

I hope this provides another way to get that bullet you really want.  Now, if you design something your gun doesn't like to shoot,  that's another story.  Stay close to a proven masterpiece (the 358-429 Keith in this case) and tweak to suite your guns, and you'll be one happy casting handloader.

Coming soon there will also be another post regarding testing with nose punches (on a lubrisizer), and how a good fitting punch can improve accuracy.

Have fun, be safe and shoot tight groups!


  1. OH! Great post..I was so impressed I've found this kind of blog..Thanks.

    injection mold

  2. This comment has been removed by the author.

  3. I definitely enjoying every little bit of it I have you bookmarked to check out new stuff you post nice post, thanks for sharing.

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  4. I don't know how many casings it can hold. It's located immediately behind the breech, so it's not safe to stick your hand in there when the gun can fire.
    Reloading Bullets

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