357 herrett case forming ??

[quicksdraw45]

I just picked up a 357 herrett barrel ,dies and some 375 winchester brass. I would just like to make sure that I have a few questions awnsered before I start .
To what length should I trim the 375 winchester brass prior to running through the die to neck it down ? It seems to me that this operation will change the length of the case .
I understand that it is improtant to headspace off the shoulder and not the rim .
Any other cautions I should be aware of before I start ?
I am not new to reloading just new to the herretts .
Thanks

[Peeter]

qicksdraw45
I have an old Thompson/Center Book. This information is out of section. "Making .30Herrett and .357Herrett Cartridge Cases for the Contender"
"Start the case forming operation by setting the end of the full length sizing die 1/4 inch from the top of the shell holder when the press is closed. Lubricate and size a test case. Trim to overall length of 1.750 inches for the .357 Herrett; chamfer neck opening inside and outside. The test case with preliminary sizing will be two long for the Contender and final sizing should be done as follows. Reset the full length sizing die down 1/8 turn (or less) at a time untill a sized case will allow the Contender to close completely and freely with no interference from the cartridge case. Dry fire a perfectly sized case and check to be sure the hammer strikes and rests against the firing pin. Successive .30-30 cases can be completely sized (except trimming and chambering) in one operation after correct die setting is obtained on test cartrige cases."
For my .30Herrett I had a little interference from the cartridge case. I had to close the gun a little hard. With that I did not have missfires. When I tested new brass I loaded a primer in the empty case and fired it.
Sorry that this is long but it is out of the book. :-D

[Johnly]

I just picked up a 357 herrett barrel ,dies and some 375 winchester brass. I would just like to make sure that I have a few questions awnsered before I start .
To what length should I trim the 375 winchester brass prior to running through the die to neck it down ? It seems to me that this operation will change the length of the case .
I understand that it is improtant to headspace off the shoulder and not the rim .
Any other cautions I should be aware of before I start ?
I am not new to reloading just new to the herretts .
Thanks

I've always made my 357 Herrett brass from Federal 30-30 brass. Personally, I'd hang on to those 375 Winchester cases and start looking for a Contender barrel chambered in that caliber, it's a natural for the Contender shooting Hornady 220 gr. FP

As mentioned by others, adjusting the sizing die until a snap to fit condition will assure the best possible brass life. I have a RCBS 357 Herrett trim die that makes case forming and trimming a snap. If you would like to borrow it, just drop me an e-mail.

[Graybeard]

In an attempt to answer the question you asked rather than providing you some other procedure for making cases from something other than what you have indicated you will use I will offer this.

As a rule of thumb when you form cases from a larger diameter bore case you ADD length in the forming operation and when you form from a smallaer bore diameter you SHORTEN the case length.

So to answer the question without giving you a hard and fast number I'd say trim to pretty much the max 1.75" length and then trim again after fire forming to the correct trim to length. You may find you want to modify that tho based on the outcome of your first few cases.

I use a Forster Power Trimmer and my drill press to do the initial case shortening for both Herrett's. The stop on my drill press isn't accurate enough to use it for final trim length but it gets me darn close and I do the final trim on my Forster Original Case Trimmer.

The biggest headache in making Herrett cases whether from .30-30 or .375 Win is getting all the excess case gone. That's why I use the drill press and power trimmer.

GB

[Old Syko]

Well Quicksdraw I'm not trying to contradict what anyone else says but I do things a little different.  I trim 1 case to max length then use it to adjust my sizer so that I just get proper closure of the action.  I then size all cases first before triming.  I understand not all sizer dies are deep enough internally to accomodate this process but if yours is like mine it can be done and you'll take a lot of guesswork out of the process of triming.  I then fireform and trim to length again.  That usually makes me good to go for 3 to 5 loads before having to trim again.

 375W cases are the way to go as I learned on this board.