Winchester 1876 Action Strength

[Shrapnel]

I was just reading in my 1876 Winchester book about the history of the 1876. There have been many stories spread about how weak the 1876 Winchester action is and I find it interesting to see what the actual field test was to determine just how weak/strong that action is. Everyone parrots the same old saying about how weak it is and yet this study seems to nullify that rumor.

Here is a picture of a blown up 1876 that the action held and yet the barrel was blown completely off the action...

[black river smith]

Shrapnel,

I also read this years ago but 'thanks' for sharing this, here. I believe that the early manufacturers did a vast array of testing on there firearms before releasing them to the public. A lot more than most realize. The same is true about their bullet designs created for a particular original model. That is why I use original molds for most of my calibers when shooting, especially with BP.

Thanks

[COSteve]

I think you are missing the point of the cautions. I talked to Steve of Steve's guns at length about this when I was considering getting a Uberti '73 in 45 Colt in early 2013. As the actions in the Uberti 1860, 1866 and 1873 clones are the same design as the 1876's action, just designed for smaller calibers, I think our discussion is relevant.

He told me that the issue isn't new rifle absolute action strength but rather the wear on the toggle pins and holes over time from over pressure caused by excessive bolt thrust. The wear will elongate the holes the pins are in over time because of the excessive pressure causing the actions to have 'slop' in them which will cause them to not lock up the action tight into battery.

That's the danger of hot loads in the action, not absolute material strength but wear over repeated firings. Many people won't shoot their rifle enough to see a problem but many of us don't feel comfortable subjecting the actions to repeated over stressing. Steve said he's also seen the receiver stretch over time with many hot loads which also will result in lack of a tight lockup into battery.

Consider the Bolt Thrust (BT) pressure the action sees from different calibers and loads. First, Bolt Thrust is the rearward pressure on the action when the round fires and it's calculated thusly:

Case radius² x pi x max pres = Bolt Thrust (BT).

The original calibers the 1873 was designed for were more powerful than that for the '60 and '66 so I'm using that design. It's also the same design Uberti uses for all three of their rifles. The 1873 Winchester was offered in .22lr, .32-20, .38-40, and .44-40. Their corresponding current peak SAAMI psi limits and bolt thrusts are calculated as follows:

.22lr: 0.226" case diameter, 22,000psi = 883lbs BT
32-20: 0.354" case diameter, 17,000psi = 1,673lbs BT
38-40: 0.465" case diameter, 14,000psi = 2,378lbs BT
44-40: 0.471" case diameter, 14,000psi = 2,439lbs BT

So, the maximum bolt thrust the action could expect to see with the original calibers it was designed to use was about 2,450lbs. Now, consider the modern calibers, their SAAMI spec max pressures and the bolt thrust they generate. The calculations are as follows:

38spl: 0.379" case diameter, 17,000psi = 1,918lbs BT
38 Spl+P: 0.379" case diameter, 18,500psi = 2,087lbs BT
45 Colt: 0.480" case diameter, 14,000psi = 2,533lbs BT
44 Spl: 0.457" case diameter, 15,500psi = 2,542lbs BT
45 Colt+P: 0.480" case diameter, 19,000psi = 3,438lbs BT
357 Mag: 0.379" case diameter, 35,000psi = 3,949lbs BT
45 Colt (Ruger): 0.480" case diameter, 25,000psi = 4,524lbs BT
44 Mag: 0.457" case diameter, 36,000psi = 5,905lbs BT

All of the underlined calibers above 38 Spl+P have a bolt thrust higher than the maximum thrust the 44-40 produces and could be thought to be outside the parameters the action was designed to reliably handle over time.

It's something worth considering and in my book, the reason that I load a bit below the standard pressure of 14,000psi in my Uberti 45 Colt '66 and '73.

[wvfarrier]

I would think that, considering modern steels, that the original limits would be far under what the modern rifles can comfortably withstand

[COSteve]

If you've never taken the cover off of the receiver on a Uberti '66 or '73, it's hard to imagine that the pins are as small as they are. Here's a couple of pictures a Uberti '73. The one on the top is with the action open and on the bottom of it closed.

There are two sets of toggle links, one on each side. As you can see, the pivot pins are a tad small and the forward pin isn't pushing on the rear toggle straight through the centerline.

According to what Steve and I talked about back in 2013, the pin at the center pivot (silver one in the top photo) takes the most load and that's where they can 'oval' the holes in the links causing the sloppiness in lockup.

My point here is that the design isn't the most durable and long term with high bolt thrust, it could lead to loosening of the action which is not a good thing.

So yes, absolute yield strength may be plenty but I see the issue as long term durability of the design when exposed to high thrust. That could cause issues.

Winchester 1873 Action Partially Open.jpg

u54bw8y7.jpg

[Pat C]

Pretty sure at lock up those links are supposed to be tight together ,NO pressure on lever or link pins.

[COSteve]

I'll direct you all to Steve of Steve's Gunz for any further comments as he's is the expert and I got my information from him. Hopefully, he'll see this thread and reply.

[Pat C]

As you can see this 1887 1873 the links are still tight as new NO gaps at the mesh points .

[Griff]

Actually, the lower pressure loads may have MORE bolt thrust than a hotter load. Without case expansion, the sidewalls of the cartridge don't fully contact the chamber walls, increasing bolt thrust. The momentary thrust of the heavier load might be mitigated by the shorter dwell time the thrust acts against the bolt... while the lighter load has less momentary thrust but over a longer dwell time due to less wall grip.

[AJMD429]

.
“…and in my book, the reason that I load a bit below the standard pressure of 14,000psi in my Uberti 45 Colt '66 and '73…”

Actually you SHOULD write a book; I’ve learned a lot from your posts (and those of others) on here…

[RIDERED350r]

I'm no gunsmith nor am I a mechanical engineer. But I am very mechanically minded, experience rebuilding engines from snowmobiles and ATVs to my diesel pickup engine.

That said, I agree with what COSteve has posted. Save the modern higher pressure loads for the modern 1886 and 1892 rifles.

I still find myself a bit dumbfounded that Uberti offers an 1873 model in 44mag.

[Nath]

I don't agree with Steve's comments.

Just how many is it of these rifles that have let go because of failed links?
I also don't think much of the calculus for bolt thrust. It's hypothetical and theoretical.
The locking mechanism is not subject to a portion of peak pressure, possibly via the primer, but not the whole case head.

[Shrapnel]

I would re emphasize the strength of this gun in withstanding the pressure that blew the barrel off the gun. This was not a new gun, as you can see, it was a well used rifle. The round in the chamber wasn’t the only round discharged in the blow up. One round in the magazine went off at the same time, causing all the damage to the forearm and magazine tube.

I would agree that wear can contribute to the lack of strength of any action, but the most obvious concern of the 1876 action being weak, is not what rumors have suggested…

[Nath]

I would re emphasize the strength of this gun in withstanding the pressure that blew the barrel off the gun. This was not a new gun, as you can see, it was a well used rifle. The round in the chamber wasn’t the only round discharged in the blow up. One round in the magazine went off at the same time, causing all the damage to the forearm and magazine tube.

I would agree that wear can contribute to the lack of strength of any action, but the most obvious concern of the 1876 action being weak, is not what rumors have suggested…

Absolutely.
The problem, if any, is not bolt thrust, I hate that term, it's percussion. A percussion not thrust.
Thrust involves a push over extended period of time. Percussion is milliseconds.
This is important. The often overlooked time factor.
The primer loads the bolt up with a tiny amount of percussion. So now in our example of the 86 any play in the links is taken up by a limited force.
Then when the case let's go of the chamber relatively lower pressure percussions that against the bolt but there is nothing to shock linkage wise because the primer already took the slack up.

[Pat C]

One of the special projects I hope to someday do is building a custom rifle off that old 1883 model 1876 receiver I have .
The main goal will be using modern high strength steel in the making of the bolt and links ,plus barrel.

Thinking of using 8620 alloy and carburizing the parts.
Maybe 4150 HTSR for pins. Modern barrel from Winchester Barrels.

[marlinman93]

Anyone whose ever owned an 1876, and loved them knows they're plenty strong for the cartridges Winchester chambered them in. Of course the testing proves they were much stronger than those who call them weak ever knew.