.357SIG Boolit Design

I’m looking to get a two cavity mold from Accurate, one cavity for each boolit shown below. These are for .357SIG and I’m wondering what kind of feedback I can get from you folks. One design is intended to be PC, and has two shallow grooves to reduce pressure via reduced bearing surface, and one of these grooves is a semi-cannelure intended to help with setback (I have successfully used cannelures on .357SIG). The other boolit design is for traditional lube, and I am placing & sizing the lube groove to minimize loss of neck tension without exposing powder to the lube. I’m not sure how much volume of lube I should have, so maybe I can make the lube groove a bit more narrow to increase neck tension. I want a large meplat with sharp corners, but I had one issue with a 0.280” meplat getting snagged on my feed ramp so I’m at a 0.250” meplat.
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Attachment 310226
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A couple of questions for you, what weight bullets do you want to use and what kind of velocity do you want to reach? What kind of gun will you be shooting (handgun or PCC and semi auto?) Are these going to be used for hunting?
As for your designs, the PC one I wouldn't add the grooves leave it stright bearing surface. As for the grease groove design, without all the dimensions it may be not enough. But this will depend on what velocity you want to achieve. I would also try and place the grease groove a little higher on the bullet due to the 357 sig's short neck.
As for neck tension I would suggest using the NOE neck size die and expanders to get the tension you want/need.

Accurate made few molds for me for the 357Sig.
357Sig is used for IPSC in Australia in Std division Major power factor.
Have a look at 35-150Z and 35-168Z.
These are great bullets for 357Sig sized .3575" Dia.
Seated to 1.152" OAL for use in glock 35 with 357Sig barrel. The guys running 2011 STI etc can seat longer. Load with Dillon carbide die set on a dillon 550B press.
Easy to reload.
A lot of people here run 40S&W brass necked down. no issues with neck tension.
These feed and function with zero issues. Laser accurate.
Hitek coated.

My advice has nothing to do with the bullet designs, but on the mold choice.

Unless you are living on your dead spouses social security, the economy of the two different cavity mold versus a four or more cavity mold is a false one. Single cavity molds are too slow to produce the volume of boolits used by a semi-auto and I will guarantee that you will find that one or the other is of greater utility than the other. Every time you cast with that two cavity mold, half of your time and effort will be wasted. Get a 4 cavity and go two by two if you must, but far better, IMO, is get separate molds, then should one fail to live up to expectations, sell it, and double down on the good one.

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Originally Posted by rintinglen

My advice has nothing to do with the bullet designs, but on the mold choice.

Unless you are living on your dead spouses social security, the economy of the two different cavity mold versus a four or more cavity mold is a false one. Single cavity molds are too slow to produce the volume of boolits used by a semi-auto and I will guarantee that you will find that one or the other is of greater utility than the other. Every time you cast with that two cavity mold, half of your time and effort will be wasted. Get a 4 cavity and go two by two if you must, but far better, IMO, is get separate molds, then should one fail to live up to expectations, sell it, and double down on the good one.

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This. Basically wasting your time one cavity at a time.

The two cavity thing is just to see which one I like best and if I will want any revisions before getting the final design in 4-c. Tom’s not replying to my emails though, so this probably is not going to happen.

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Originally Posted by justindad

The two cavity thing is just to see which one I like best and if I will want any revisions before getting the final design in 4-c. Tom’s not replying to my emails though, so this probably is not going to happen.

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Give him time, he is a one man shop if I remember correctly. The last design I submitted took well over a month to get cataloged.

I'm thinking a simple tumble lube design with or without gas check would solve both your "reduced bearing surface" and cannelure needs. Just specify groove location on the critical one. Could be PC'd, tumbled, or conventional lubed. Just make sure all the grooves will be inside the case neck if you're going to grease it.