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40-65/40-70ss 2.5 inch Chambering (Read 960 times)

bobw Frequent Elocutionist Offline Posts: 1591 Location: NW, Iowa Joined: Mar 19^th, 2013	40-65/40-70ss 2.5 inch Chambering Jan 27^th, 2025 at 12:44pm	Print Post
	I’m considering chambering a gun I’m currently working on in the 40-70ss. I see there is a 40-70ss Shiloh which I assume is designed for a modern barrel of .408. From what I understand the original usually used a paper patched bullet and don’t shoot as well using a lubed bullet. Can anyone enlighten me on the original 40-70ss and the Shiloh version, the good, bad and ugly? Are they the same basic brass? It looks like the Shiloh has a thicker rim but is that all? Can both be made from 30-40 Krag brass? What kind of issues will I run into using it? I see folks getting along really well with it and others not so much. Thanks Bob

	Robert Warren
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emmett22405 Full Member Offline Posts: 164 Location: Virginia Joined: Sep 21^st, 2009	Re: 40-65/40-70ss 2.5 inch Chambering Reply #1 - Jan 27^th, 2025 at 12:52pm	Print Post
	Howdy My first Shiloh was in 40-70 SS. The rim size etc was perfectly met by Buffalo Arms who lengthened original 30-40 Krag brass. I believe my bullet diam was closer to 0.407 than .0408 for best results.


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marlinguy Frequent Elocutionist Offline Ballards may be weaker, but they sure are neater! Posts: 16444 Location: Oregon Joined: Feb 2^nd, 2009	Re: 40-65/40-70ss 2.5 inch Chambering Reply #2 - Jan 27^th, 2025 at 1:56pm	Print Post
	I can't speak for the Shiloh .40-70SS, but I shoot several old originals in this cartridge, plus a couple newly barreled chambered in recent years. All mine are in the .410"-.411" groove diameter and those old enough to have used paper patch bullets shoot extremely well with grease groove bullets still. Mine are Rolling Blocks and Ballard rifles and have slower twist in the original barrels, but faster 16" or 14.5" twists in the rebarreled rifles. All loaded with grease groove bullets and shooting smokeless 4198 powder.

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nuclearcricket Oldtimer Offline Posts: 774 Joined: Oct 15^th, 2008	Re: 40-65/40-70ss 2.5 inch Chambering Reply #3 - Jan 27^th, 2025 at 4:12pm	Print Post
	The big problem with the 40-70SS is brass. I would suggest that before you take the final leap, find a good source of brass and stock up. Otherwise you may end up with a very nice rifle you can't shoot due to little to no brass. That would just flat out suck. SAm


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marlinguy Frequent Elocutionist Offline Ballards may be weaker, but they sure are neater! Posts: 16444 Location: Oregon Joined: Feb 2^nd, 2009	Re: 40-65/40-70ss 2.5 inch Chambering Reply #4 - Jan 27^th, 2025 at 4:32pm	Print Post
	nuclearcricket wrote on Jan 27^th, 2025 at 4:12pm: The big problem with the 40-70SS is brass. I would suggest that before you take the final leap, find a good source of brass and stock up. Otherwise you may end up with a very nice rifle you can't shoot due to little to no brass. That would just flat out suck. SAm Very good point Sam! I got all my brass long before it became extinct! If I was doing it today using a new barrel I'd go for the shorter chamber that uses .30-40 Krag or .303 British brass fire formed and loaded as is length. They get the same velocities, but with easily purchased brass at cheap prices.

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KFW Oldtimer Offline Posts: 565 Location: Powell Wy. Joined: Dec 18^th, 2016	Re: 40-65/40-70ss 2.5 inch Chambering Reply #5 - Jan 27^th, 2025 at 4:39pm	Print Post
	I chambered my last barrel with a Pacific .40-70 Shiloh reamer. I use only Hornady .405 brass. Once full length sized with RCBS dies many will not chamber immediately with out a a small amount of additional work on the case head web diameter. Rim thickness has not been a issue. I spin the problem cases in a lathe collet and kiss it with a needle file, .001-.002" removal is all it takes. From there on no issues.


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nuclearcricket Oldtimer Offline Posts: 774 Joined: Oct 15^th, 2008	Re: 40-65/40-70ss 2.5 inch Chambering Reply #6 - Jan 27^th, 2025 at 7:06pm	Print Post
	As a shorter alturnative you may want to consider the 40-60 Maynard. Not posative but think that can be made from 303 brass. And from what I have seen its a very good cartridge. Sam


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steel-pounder Full Member Offline Posts: 167 Joined: Mar 26^th, 2016	Re: 40-65/40-70ss 2.5 inch Chambering Reply #7 - Jan 27^th, 2025 at 7:21pm	Print Post
	I just chambered a high wall with a ptg C-Sharps 40-70 SS reamer. shortened .405 winchester brass chambers perfectly.


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bobw Frequent Elocutionist Offline Posts: 1591 Location: NW, Iowa Joined: Mar 19^th, 2013	Re: 40-65/40-70ss 2.5 inch Chambering Reply #8 - Jan 27^th, 2025 at 7:34pm	Print Post
	The first 2 pictures just support each other. I'm showing them because the 40-70 is not in my book but the 40-65 is. KFW looks like the Shiloh version was made so the .405 brass could be used, specs look like they are really close. The Shiloh specs I am showing are from the 4D rental reamer info. I assume you are sizing with the standard 40-70 die? How is this cartridge performing? Bob

	Robert Warren
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KFW Oldtimer Offline Posts: 565 Location: Powell Wy. Joined: Dec 18^th, 2016	Re: 40-65/40-70ss 2.5 inch Chambering Reply #9 - Jan 27^th, 2025 at 8:06pm	Print Post
	From BobW "I assume you are sizing with the standard 40-70 die? How is this cartridge performing?" Yah I was slow to join the .40-70 party after yrs of reading Venturino's endorsements. But I have really warmed up to the caliber this summer in 2 matches, it may put my .40-82 shil. on the back burner. That said, I only size cases once as I shoot PP DD


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ssdave Frequent Elocutionist Offline Posts: 1857 Location: Eastern Oregon Joined: Apr 16^th, 2004	Re: 40-65/40-70ss 2.5 inch Chambering Reply #10 - Jan 27^th, 2025 at 8:26pm	Print Post
	Bob, I've got this reamer if you want to borrow it. One option is always to not run it all the way in, and turn the rim recess on the lathe if you want to use 30-40 to fireform. (You need to *Login* or *Register* to view media files and links)


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Deadeye Bly Frequent Elocutionist Offline Posts: 1077 Location: Stephens City Joined: Feb 25^th, 2011	Re: 40-65/40-70ss 2.5 inch Chambering Reply #11 - Jan 27^th, 2025 at 9:33pm	Print Post
	I've got a Shiloh 40/70SS and use the stretched Krag brass from BACO mainly. It fits and works well. I've also got some 405 brass that fits the rifle. I had to turn the necks to get the the case small enough to chamber with a bullet seated. I had to reduce some of the cases right in front of the rim so they would chamber. 405 brass is not available right now so you had better check on the BACO brass. I've also got the Pacific reamer for the 40/70 to use 405 brass. I've used it on 40/70 and 40/60 Maynard chambers by short chambering. Krag brass works well for the 40/60 Maynard. I've done 40/50 SS chambers with it by short chambering. Krag or 303 Brit brass works for the 40/50.


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LRF Oldtimer Offline Posts: 636 Location: MN Joined: May 8^th, 2010	Re: 40-65/40-70ss 2.5 inch Chambering Reply #12 - Jan 28^th, 2025 at 6:21am	Print Post
	Bob, if it is of any help, the very first rifle I every built (circa 1980) was in 40-70-2.5" SS and for the build I bought an original Sharps paper patch cartridge which I still have. So here are the dimensions from that cartridge: OAL: 3.278" Bullet length: 1.131 Bullet diameter: over the patch .403" Diameter case at mouth: .424" Diameter at base: .454" Rim diameter: .548" Case length: 2.500" Rim thickness: .069" I don't know how these compare to the measurements listed above but at least you now have a base line to go from.


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jhm Frequent Elocutionist Offline Posts: 1595 Location: georgia Joined: Sep 4^th, 2011	Re: 40-65/40-70ss 2.5 inch Chambering Reply #13 - Jan 28^th, 2025 at 7:07am	Print Post
	I have an original hi wall in 40-70 st that I use shortened 405 brass and a .410 Snover bullet in. It has an old Green Mountain barrel and shoots quite well. A gentleman here chambered the barrel for me many years ago and I forget who he was (it's been a long time). Still using the original 50 cases I bought when I built the gun. They were Hornady and with care will last a good long time. JMH


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bobw Frequent Elocutionist Offline Posts: 1591 Location: NW, Iowa Joined: Mar 19^th, 2013	Re: 40-65/40-70ss 2.5 inch Chambering Reply #14 - Jan 28^th, 2025 at 11:20am	Print Post
	Thanks for all the information everyone, you never disappoint with the vast experience on this board! Dave, that reamer looks nearly the same as the Shiloh reamer 4D has. I will be talking with you as I get closer to chambering. Thanks! Luckily, somewhere around here, I have 50 .405 pieces of brass for sure. Bob

	Robert Warren
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