40-70 SS rim thickness

[august west]

What is the origin of there being two different rim thicknesses for Shiloh rifles in this caliber? BACO has cases and loaded ammo listed for Shiloh rifles, some with .064" rim and some swaged to increase it to .068". If the cases come already at .064", what is the use of chambering deeper just so that the cases don't fit correctly and have to be altered? Or is there something I'm missing here?

[MikeT]

I think it has something to do with the use of 405 Win brass. The original 40-70SS had a thinner rim than the 405 winchester, which came along latter during the smokeless powder era. This was probably done by winchester so nobody could mistakenly chamber a 405 in an original BP 40-70SS.

Now, we have some 40-70SS chambers with the original rim and some chambers setup to use 405 brass.

Keep on hav'n fun!
MikeT

[august west]

That makes sense. I guess my question is which run thickness is standard from Shiloh, and does it matter that much. Since. 064 thickness brass is really available can't I go ahead and get that?

Since there almost no difference between these two run thicknesses I should be able to use the thinner one no matter what, right? I mean, .004 is the thickness of a piece of copier paper. I can't see that making a lot of difference.

Thanks
Ryan

[august west]

Sorry, rim not run.

[beltfed]

Ryan,
INdeed,you might find that you would have trouble closing the breech block on a "0.064" 40-70 Shiloh with the 0.068" 405 brass.
I tried to use 405 Hornady brass to neck down to 38-72 in a Win 1895 rifle, and it would Not close and lock.
It is noted that both the 38-72 and the 40-72 Win ctges were designed from the basic 40-70 SS case and had the "old" 0.064 headspace.
The 30-40 Krag case-used by BACO to form to 40-70SS. apparently also came from the 40-70SS necked down to 30 cal. It is also 0.064 rim thickness

That seemingly small 0.004 can be "TOO BIG" to be useful.
Now, some people were machining that 0.004" off the Front of the Rim ( not from the face of the case head
in order to utilize formerly available 405 Hornady brass.

I sold my '95, cal 38-72 before I learned that trick. Wish now that I had not sold it.
Since I had built a 40-72 on a Ruger Number 1 and had plenty of 405 Hornady brass.
I even have both 38-72 and 40-72 (cum 405 Hornady brass fit) Dan Theodore's reamers.
We did slightly rechamber a friend's Shiloh 40-70 to use the full length 405 Hornady brass. Simple,
no need to trim back from 2.58" to 2.5" for the (formerly) 40-70 chamber/rim size.
beltfed/arnie

[august west]

Ok I see.

So what run thickness comes stock from Shiloh? If it comes 068, can I use the thinner rim cases?

I just ordered my rifle this week. Can I request 064 depth so that I can use the more easily obtained cases that baco sells now?

They're both listed as"for Shiloh" in the back catalog.

Thanks
Ryan

[Clarence]

Ryan,

Your best bet is to ask Kirk. I believe he'll tell you that the standard chambering is for 0.068" rims; that is how a Shiloh I owned in the 1990's was, and I used the 0.068' rim in that rifle. 0.068" rims is also indicated as the Shiloh standard in the BA catalog.

Assuming my earlier statement is correct, I don't understand the thought process of using thinner rimmed brass and a non-standard chamber when the correct brass is manufactured and you have plenty of time to get the correct brass before you get the rifle. Using thinner rims may encourage case stretch, since it is the equivalent of 0.004" headspace. And, the Buffalo Arms 0.064" rimmed brass may not be available some time down the road...

My current .40-70 SS (not a Shiloh) was chambered specifically for the Hornady .405 brass, which works well, but I'd be in trouble if I didn't have plenty of brass.

Clarence

[august west]

That makes sense. I wondered if that small amount of head space would be a problem and I guess it is.

Thanks
Ryan

[Kurt]

I have .40-70 cases made by BA stretched .30-40 that are .068" the .405 hornady cases are .068 that fit my Shiloh. The only problem I had with this brass is the base diameter had to be swaged down. I did this by turning the round EZ edge off the bottom of the Lyman sizing die.
I also have Bertram brass marked .40-70 and the rim thickness on that .068".
BA made brass for the stretched .30-40 .40-70 for the C-Sharps that uses a thinner rim thickness but I don't remember the thickness but I had some by mistake and the cases separated in my rifle.

[J.B.]

I'm running with BACo Krag modified cases in our 40/70 straight from Shiloh and they are going fine. Some rubbed a little at the breech face initially but a few runs over some fine wet and dry laid on a flat surface ( ie. glass or granite bench ) had them fitting perfectly. I'd give BACo a call to see if they have the parent cases ready to work with as I believe that was a problem for a while. If you were to order 80+ cases or more ..you may find they gear up to produce them. There is a lot in their inventory and keeping up with demand on all the chamberings and the variations thereof...would be a tedious task. If you could source some Hornady 405... as Kurt says they will work but need some fine tuning on the standard Shiloh chamber. The problem comes about with neck thickness... I purchased two boxes when I saw them and now keep them for paper patch work in my sons rifle and they work well for that. Without neck turning... they are a little thick at the neck to seat gg bullets at .408/.409 diameter.
J.B.

[august west]

Thanks very much. 405 brass is unobtainable now too so I'll stick with the standard 068 rim thickness cases. I'll call BAC and see if they will be doing some in upcoming weeks. No sense re inventing the wheel.

Thanks
Ryan