270 Sherman just starting out

ryan burget

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Hello I’m new to the wildcat world and I am having a 270 Sherman built. I have a few questions. My first question is on fire forming first I read they you have to establish a shoulder on a 270 bullet by first necking it up to .30 cal the. Back down? If that’s the case why can’t I just start with a 30-06 case as skip the first step? Second the I have a lot of rl23 and haven’t seen much for reloading data on it what is or how do I determine a good starting load so I don’t over charge or under charge? All help is appreciated thank you!
 

338 dude

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Hello I’m new to the wildcat world and I am having a 270 Sherman built. I have a few questions. My first question is on fire forming first I read they you have to establish a shoulder on a 270 bullet by first necking it up to .30 cal the. Back down? If that’s the case why can’t I just start with a 30-06 case as skip the first step? Second the I have a lot of rl23 and haven’t seen much for reloading data on it what is or how do I determine a good starting load so I don’t over charge or under charge? All help is appreciated thank you!
Have you checked their website on this forum somewhere there was a thread about load data out for Sherman Wildcats
 

waspocrew

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30-06 brass will end up too short in the neck. You’ll want to use 270 Win or 280 Rem brass to start with. The false shoulder is very important to establish correct headspace.

Here’s an example with the false shoulder prior to fireforming. It’s definitely a lot of brass movement. 6.5 Sherman, but pretty similar.


4CED117C-A0CE-48C8-8E29-30D4F2CADECC.jpeg
 

jpfrog

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724A7035-C425-42F3-83F3-A6F29975F3A0.jpeg
Hard to tell from the pic, but the brass on the right is a 270win formed to 280 Sherman, which is extremely close to your 270 Sherman and uses the same forming process. The brass on the left is a 30-06 formed to a 30-06AI. There is about .030” difference in case length. Blow the AI shoulder forward to Sherman dimensions and your neck will suffer a bit.
 

codyadams

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Yup, as stated, the 30-06 is a slightly different case than a .280 rem or .270 win. I have put together and worked on two different .270 Sherman's, and have used Reloder 26, Reloder 16 and H1000. What bullet do you plan on running?
 

ryan burget

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Yup, as stated, the 30-06 is a slightly different case than a .280 rem or .270 win. I have put together and worked on two different .270 Sherman's, and have used Reloder 26, Reloder 16 and H1000. What bullet do you plan on running?
I plan on running the Berger 170 grain or 165 nosler accubond I have a lot of reloader 23
 

Alibiiv

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Hello I’m new to the wildcat world and I am having a 270 Sherman built. I have a few questions. My first question is on fire forming first I read they you have to establish a shoulder on a 270 bullet by first necking it up to .30 cal the. Back down? If that’s the case why can’t I just start with a 30-06 case as skip the first step? Second the I have a lot of rl23 and haven’t seen much for reloading data on it what is or how do I determine a good starting load so I don’t over charge or under charge? All help is appreciated thank you!

There's a lot of data within these forums that ought to help answer some of your questions about fire forming brass. I started fire forming brass for the .270 Ackley Improved a few years ago. You "can" make a false shoulder as has been suggested in one of the replies. I am not familiar with the .270 Sherman case's overall dimension so not certain about using .270 Winchester brass. For me something that also was suggested was to leave the bullet seated out the .270 Winchester just far enough so as to keep the base of the cartridge held tightly against the bolt face to fire form the brass with. There's also the "hydro forming" process that will require special dies, Google or the forum will be your best friend here. No matter what process you decide upon, I "strongly" recommend that you make an investment in an annealing system before you decide to get too far into the process of fire forming. It will save you a lot of time, money and brass. I use a Sinclair mandrel die and a Forster neck turning system to clean up the necks on the cases <<-----and your going to need all that stuff too......... Some people may disagree with this statement, however I started out learning the fire forming process with inexpensive brass (Winchester) before I decided to invest in good brass to do my fire forming. Good luck with your project.
 

264MHC

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Unless you have or are planning to get a 280 or 280 AI in the future, I would probably use one of those for the brass. The case length is right for it and you will only have one operation, necking down, to create to false shoulder. 280 AI brass would probably be ideal because its already pretty close to the Sherman dimensions so wouldn't have as far to go to blow out. RL 23 should be a really good powder for 270 Sherman, works great in my 280 AI. You should be able to find load data for it in standard 270, then just use the max load in that data as a start load in fireformed sherman brass, and work up from there.
 

264MHC

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Alliant lists between 57.1 and 57.8 as max for various 150 grain loads in 270 win, and quickload shows 56 as max with the 170 Berger. The 270 Sherman has a pretty significant jump in case capacity over 270 Win so I would think 56 grains would be a good safe place to start with 170 class bullets in the Sherman.
 

Alibiiv

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Alliant lists between 57.1 and 57.8 as max for various 150 grain loads in 270 win, and quickload shows 56 as max with the 170 Berger. The 270 Sherman has a pretty significant jump in case capacity over 270 Win so I would think 56 grains would be a good safe place to start with 170 class bullets in the Sherman.

With the .270 Ackley Improved I did not have any data to work up a load with. After doing some research I decided to start with 1/2 grain less then the SAAMI data for the .270 Winchester. I believe that starting the fire forming with the same data for the .270 Sherman ought to work quite well to fire form brass. What I have found after working on load development is that the .270 Ackley Improved is very close to the data provided for the .270 Winchester Short magnum, getting a little better performance with less powder than in the .270 WSM.

And......if you are building a .270 Sherman, Rich ought to be able to answer any questions that the OP has and usually he has some brass or is in the process of making brass for the round.
 

FEENIX

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30-06 brass will end up too short in the neck. You’ll want to use 270 Win or 280 Rem brass to start with. The false shoulder is very important to establish correct headspace.

Here’s an example with the false shoulder prior to fireforming. It’s definitely a lot of brass movement. 6.5 Sherman, but pretty similar.


View attachment 287707
Yep, that's what I noted on his other post ...
The .270 Win and .280 Rem has a case length of 2.540" and the .30-06 has 2.494". The .270/.280 is a better choice to fire-form to .270 Sherman. Rich (@elkaholic) is the designer and SME with this cartridge.
(#26 of https://www.longrangehunting.com/threads/270-ackley-vs-270-sherman.137449/page-2)

Ed
 

codyadams

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Unless you have or are planning to get a 280 or 280 AI in the future, I would probably use one of those for the brass. The case length is right for it and you will only have one operation, necking down, to create to false shoulder. 280 AI brass would probably be ideal because its already pretty close to the Sherman dimensions so wouldn't have as far to go to blow out. RL 23 should be a really good powder for 270 Sherman, works great in my 280 AI. You should be able to find load data for it in standard 270, then just use the max load in that data as a start load in fireformed sherman brass, and work up from there.
7mm was not enough of a shoulder when I tried it, I did not get a solid shoulder, it is only .007". I had to neck up to 30 cal before I got an appropriate false shoulder. 280 ai brass would still be a good option though.
 

264MHC

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Interesting, I've always assumed it would work. Guess I shouldn't post something I haven't tried. I've only done it from 6.5 to 6mm, but .021 is a lot more than .007 in this instance.
 
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