Author Topic: Cartridge base alteration??  (Read 732 times)

Offline Black River Smith

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Cartridge base alteration??
« on: July 08, 2024, 07:47:22 PM »
I purchased fired brass in 357Mag about a year ago.  While separating the brands I came across brass that had been altered in a manner I have never seen before.  The brass brand is Norma.

Sooooo, the bottom of the base has been thinned down by tapering from about half the radius to the outer edge the base.

Why would someone do this to 100 pieces of brass (nice even job on all the pieces, also)?  One idea, I thought of, was to alleviate any drag when cycling into the firing position on certain 'stepped recoil shields' (like Uberti revolvers).  MAYBE?

Thanks for any insight and -- Is the brass safe to reload and use in rifles, like this, using middle level loads like 6 grains of Unique?
Black River Smith

Offline Abilene

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Re: Cartridge base alteration??
« Reply #1 on: July 08, 2024, 09:21:26 PM »
weird!  Your guess as to why is as good as any, but it would have been easier to file the recoil shield ridge.  Maybe someone else has seen this. I should think it would be okay to use but I ain't a ballistician.

Offline Reverend P. Babcock Chase

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Re: Cartridge base alteration??
« Reply #2 on: July 08, 2024, 10:50:21 PM »
Howdy Black RS,

It's hard for me to visualize, but if it is a chamfer it could be to allow an extractor (on a rifle or auto pistol .357?) to ride over the rim on closure of the bolt or slide. SWAG

Rev. Chase

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Re: Cartridge base alteration??
« Reply #3 on: Today at 03:49:42 PM »

Offline Black River Smith

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Re: Cartridge base alteration??
« Reply #3 on: July 09, 2024, 07:54:12 AM »
Howdy Black RS,

It's hard for me to visualize, but if it is a chamfer it could be to allow an extractor (on a rifle or auto pistol .357?) to ride over the rim on closure of the bolt or slide. SWAG

Rev. Chase

Now that is a different option or clever idea.  Imagining it, that way, definitely could make sense.
Black River Smith

Offline Coffinmaker

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Re: Cartridge base alteration??
« Reply #4 on: July 09, 2024, 08:41:09 AM »

 :) Well, well well  :P

In all my Sordid years as a Gunplumber, never saw anyone do that.  I suppose I could come up with some kind of WAG, but for the life of me, I can't think of any good reason to do that.  I would also suspect it will wobble some in the loading press.  "Weebles Wobble but don't fall down."

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Offline Reverend P. Babcock Chase

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Re: Cartridge base alteration??
« Reply #5 on: July 09, 2024, 09:33:40 AM »
It strikes me that a photo would probably help all of us come up with so other ideas.

Rev. Chase

Offline Tascosa Joe

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Re: Cartridge base alteration??
« Reply #6 on: July 09, 2024, 09:41:06 AM »
Here is another SWAG, the brass could have been modified to shot in a British Rook rifle.  The Brits built those things in all sorts of custom calibers.
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Offline Black River Smith

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Re: Cartridge base alteration??
« Reply #7 on: July 09, 2024, 11:45:51 AM »
I was hoping that someone had already worked their brass like this before, so that I would not need to add pictures, but here we go.  Hope they all fit in this posting.  These are different pieces of the lot, on different colored surfaces, to hopefully show a more distinct image.  The last photo is three pieces pushed through a white piece of paper for a flush surface image.
Black River Smith

Offline Black River Smith

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Re: Cartridge base alteration??
« Reply #8 on: July 09, 2024, 12:00:41 PM »
:) Well, well well  :P

In all my Sordid years as a Gunplumber, never saw anyone do that.  I suppose I could come up with some kind of WAG, but for the life of me, I can't think of any good reason to do that.  I would also suspect it will wobble some in the loading press.  "Weebles Wobble but don't fall down."

I got Nothin

Coffinmaker,
You are correct, these pieces do wobble in the shellholder, more than flat base brass.  I did already resize these pieces and had to maneuver them into the die.  But since I still use a single stage press after 30+yrs, it is workable.
Black River Smith

Offline Tascosa Joe

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Re: Cartridge base alteration??
« Reply #9 on: July 09, 2024, 01:26:24 PM »
When the Double Gun Journal was still in existence, Ross Siefreid (spelled wrong), was always trimming this brass case or that case to fit some European double rifle or single shot and a lot of the cases were trimmed in the style of your .357 Mag cases.
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Offline DJ

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Re: Cartridge base alteration??
« Reply #10 on: July 09, 2024, 07:35:51 PM »
The rifle-extractor theory makes sense.
I've seen it done on cases for the Evans--not a .357, of course, but principle makes sense.  Some bevel also seems to help other extractors ease over the rim.



Offline Black River Smith

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Re: Cartridge base alteration??
« Reply #11 on: July 09, 2024, 08:30:28 PM »
When the Double Gun Journal was still in existence, Ross Siefreid (spelled wrong), was always trimming this brass case or that case to fit some European double rifle or single shot and a lot of the cases were trimmed in the style of your .357 Mag cases.

Ok, so I can see the bevel as a smoother contact point on closing of the shotgun style recoil shields and lock-up.  And also a smoother slide surface for the extractor to glide over during closure of bolts or slides (faster lock up??).

I will add this last comment.  I tried this brass in my Rossi '92 by just inserting and closing the bolt 'slowly'.  Yes very smooth easy closure but the extractor did leave a very small but visible mark on the beveled area, that was not there before.  Using a standard shaped piece of brass, I see no markings using same method of closing.  I don't feel real concerned about this mark, brass may be scraped or chewed up faster, than standard.  At this time, I am not shooting a lot of rounds, that offer, so it still would last me a long, long time.  If no splitting occurs.

With the above statements it still comes down to.... Does anyone have any concerns or issues with reloading and using this brass in handguns and '92 style rifles?  Coffinmaker, What does you say?
Black River Smith

Offline Professor Marvel

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Re: Cartridge base alteration??
« Reply #12 on: July 09, 2024, 10:16:18 PM »
The modern cases have a solid head. That is where al the pressure happens.
A trimmed, beveled, or thinned rim should have no bearing on the saftey of the brass, only
Possible theoretical xtraction issues.

I would not hesitate to shoot this as long as the case heads measure to spec and show no signs of
Overpressure or excessive sizing.
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Offline Tornado

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Re: Cartridge base alteration??
« Reply #13 on: July 10, 2024, 07:20:22 AM »
I do something similar to my wildcated 1905 Winchester.  I take a 38 special and reduce the diameter of the rim, then bevel the back of the rim, similar to this brass.  This allows it to fit and operate with the existing extractor.

Offline Lucky R. K.

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Re: Cartridge base alteration??
« Reply #14 on: July 10, 2024, 07:53:22 AM »

My guess is that they were modified to be used in a Rook rifle. Get a copy of Cartridges of the World and compare dimensions. I used to have a Jefferies 300 Rook and your brass looks like what I shot. We made the cases from 32 H&R mag brass.
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Offline Reverend P. Babcock Chase

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Re: Cartridge base alteration??
« Reply #15 on: July 10, 2024, 09:32:47 AM »
Howdy cartridge historians,

The previous mentions of "Rook" rifles have gotten me thinking. What does a Rook taste like?

Rev. Chase

Offline Coffinmaker

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Re: Cartridge base alteration??
« Reply #16 on: July 10, 2024, 09:38:43 AM »

 :) Well, since I was Asked  :P

I would see no problem shooting the Brass as shown.  I would also be want to refer to the above post from the esteemed Perfesser Marvelous.  All that beveling was done at the perimeter of the base and poses no pressure or stress issues.  Other than a little Weeble Wobble in the loading press, quite shootable.  Fire Away!!

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Re: Cartridge base alteration??
« Reply #17 on: July 10, 2024, 09:43:03 AM »
I do something similar to my wildcated 1905 Winchester.  I take a 38 special and reduce the diameter of the rim, then bevel the back of the rim, similar to this brass.  This allows it to fit and operate with the existing extractor.

Some people do this with .357 Magnum brass to make .351 Self Loading.  .357 Maximum is a "better" parent case, but people certainly seem to be able to get the Magnum brass to work as long as they seat the bullet to a usable OAL.

You didn't mention an extractor groove being cut as well, so I'm assuming that wasn't done.  Some people do it when making .351 brass and some don't.

I think the rim would need to be turned down a tiny bit too.  I don't see any evidence of that on your brass.

The diameter of the case mouth before sizing may be a hint as to the brass's past life.  I know the .351 Self Loading uses a smaller bullet than the .357 Magnum.

The Rook angle is certainly interesting too.

Offline Tascosa Joe

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Re: Cartridge base alteration??
« Reply #18 on: July 10, 2024, 01:31:03 PM »
Howdy cartridge historians,

The previous mentions of "Rook" rifles have gotten me thinking. What does a Rook taste like?

Rev. Chase
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Offline Tascosa Joe

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Re: Cartridge base alteration??
« Reply #19 on: July 10, 2024, 01:36:16 PM »
Lucky RK is probably more versed than I on this subject.   All the Rook rifles (less than 20) that I have seen have been small single shot rifles most of the ones I have seen have been a variation of a falling block and in a .32 bore diameter.
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