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Author Topic: Forming .357 Herrett Cases  (Read 2606 times)
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Posts: 103

« on: March 07, 2012, 09:11:45 PM »

I have a new-to-me .357 Herrett barrel for my Contender pistol.  I have two approaches to making the .357 Herrett cases.

(1) I have lots of .30-30 Winchester brass (who doesn't).  These will take a bit of work to neck it up from .30 to .357.  I plan on expanding the neck in steps using different RCBS expander balls between .30 and .357 diameters.  Then run the lubricated case into the RCBS .357 Herrett trim die, cutting off the excess and trimming the case mouth inside and out.  I'm not sure if the shoulder will be quite right and plan on fire forming the cases with light very light bullets to blow out the case wall and shoulder to the proper size and location.  From then on it will be neck sizing only.

(2) I have some .375 Winchester brass from shooting my .375 Win Contender barrel.  This should be straight forward.  Run a lubricated case into the RCBS .357 Herrett trim die, cut off the excess and trim up the case mouth inside and out.  This too will require fire forming, again with light bullets.  The only thing I worry about with this approach is the .375 Win cases are a bit thicker.  Will I need to inside neck turn these cases?  What about outside neck turning?

I know I can purchase .357 Herrett brass already formed, but it is expensive and .30-30 Win cases are plentiful, and I can get .375 Win brass easily.

Are there any other cases that might make for good starters for his reforming? 
Posts: 23

« Reply #1 on: March 25, 2012, 12:37:39 AM »

I would stick with the 30-30 WCF case, the .375 Win. as you mentioned is thicker and stronger. If your .357 Herret has a tight neck you may run into problems with excessive pressure as the result of the case neck not being able to expand properly. The forming of your cases from the .375 Win. may result in an overly thick neck, without inside reaming or neck turning dangerous pressures may arise. This round was designed around reformed 30-30 cases anyway, this way you shouldn't to neck ream or outside turn the cases for safe and proper usage.
osprey steve
Posts: 2

« Reply #2 on: April 05, 2013, 12:35:26 PM »

No reason to use 375 win brass.Its too thick and will raise pressures.You don't need to neck up before using the trim die.You are gonna trim down below the original caliber section anyway.Just lube the clean 30/30 case,and run it up into the trim die.Then cut the excess with a hacksaw blade and file the rest flush.Inside/outside chamfer,and you are ready to prime and load for fireforming.Firefoming works best with standard bullet weights and reduced charges.Cast bullets loaded about a grain or two under max work well for me and keep cost down.
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