Monday, July 13, 2009

Thoughts on the Use of Smokeless Powder in the 1876 Reproductions

Well, I have an 1876 reproduction. I have done a bit of case production and reloading. Just a bit. Others on-line like Grizzly Adams, John Boy, Larryo, Coyote Nose and Buck Stinson (by a long shot!) have done a lot more loading and shooting as well. Over at CAS City we had a bit of a tiff when loading this case with blasphemous smokeless powders was mentioned. Some other fellows (not any of those mentioned above) got tied in a knot over the idea. It is unfortunate, but it may come to pass in the short run that we'll have to load smokeless to shoot these guns. It just might be that explosive BP will be very much more restricted (just call me paranoid and then humor the supposition).

Lyman's 49th edition of their loading manual was recently released. In it Brian Pearce has an article concerning loading of the Winchester 1876 replicas/reproductions. FWIW, he used Chaparral rifles. In that article, Mr. Pearce says that the MODERN 1876s can handle 28K CUP pressures. No where does he say how he came to that conclusion.

He also provides loading data for the .40-65, .45-60, and .45-75. In the .45s he uses the same Lyman 457191 and 457122 bullets. These are nominally 292 and 330 gr. respectively. He did not use the standard 350 gr. 457192 in the .45-75. Pity. It appears that he loaded based on the 28K CUP limit, although not consistently so.

Powders used include IMR and H 4198, H4895, Varget, Pyrodex Pistol pellets (30 gr.), Trail Boss, 2400, AA2015 and AA5744 (XMP5744). Charges are a bit all over the place with some likely producing pressures of sub 15K CUP and others quite a bit more (the last is a supposition on my part based on my personal experience). No pressure data is given. After having read the article it would appear (perhaps due to editing) that he simply thought this or that powder would do well and used it. I don't suppose that he damaged any rifles, but I don't know one way or the other.

To narrow it down a bit more, I'd like to use H4198. IMR 4198 (and H4198 is the next slowest in the burn rate chart) has long been used as a sub for BP in the English express cartridges at a rate of 40% of the BP charge. That would be 30 gr. for a 75 gr. charge or 28 gr. for a 70 gr. charge in a more modern case. His lower charges with lighter bullets produce better results than is my experience in my carbine (22" barrel). I've re-read his article a number of times and can't shake this feeling that there's some sort of disconnect. In other words, something isn't quite right somewhere. There can be a number dimensional differences in the guns which affect the ballistics. Whether it is with me, my rifle, or with Mr. Pearce and/or his rifle and the longer barrel, I can't be certain.

Again, while I'd rather use BP I realize that there may be reasons in the future I won't be able to. I'd like to prepare for those contingencies.

So, what do you shooters of the toggle-link guns, specifically the 1876 and its reproductions think? Have you read the article? What do you do?

I don't think WHAT we do is critical, or might not be critical in the future, as much as being able to do anything/something.

I personally like Pyrodex. In my experience it gives ballistics very much like GOEX FFg.

Those pressure graphs were posted someplace (here or at CAS city). BP is an EXPLOSIVE and has a pressure curve to match that description.

IMR SR4759 is what I've been using. I wish there was real pressure data. I believe it is coming.

The thing is, simply using BP doesn't negate risk. We know that because guns failed with BP which is why there was a demand for safer actions even before the coming of the smokeless powders.

I got to shoot my '76 a bit this morning. Not much as I didn't want to tick off Mom's neighbors but I did want them to know I was there. Anyway, I had two failures to fire at first strike but both of those rounds went off with the second hammer blow. Ten-X ammo in Bertram cases. Smokeless (IMR SR4759 is what it looks like). The problem wasn't the powder, it was headspace. This is what comes from having to form brass.

Let's move this to another angle.

.45-70 Govt loads using various powders are a known quantity. I believe somebody mentioned their Trapdoor in this or another topic in this regard. While it isn't always wise to extrapolate data, the .45-75 has about the same capacity as the .45-70 albeit in a bottle necked case. Tests have shown (even back in the 1870s and 1880s) that the bottle necked cases of similar capacity and charge will give about 2K CUP more pressure than the straight case version. This is one reason the US Govt went with the kinda straight cased .45-70 (they were trying to maximize the margin of safety even then). Assuming the same bullet being used (and this is why we use a 50 gr. lighter bullet in the .45-75), if a given charge with a given bullet is OK for the Trapdoor, why then would it not be ok in the 1876? How about if one allowed .5-1 gr. reduction in the .45-75 to allow for that pressure increase? Yes, when velocities have exceeded the BP "envelope" so have pressures.

So, the old 40% rule would say that in the .45-75 a charge of 30 gr. IMR 4198 under the 350 gr. bullet would match the old BP velocities. In my experience the printed maxs are 24-26 gr. and these give the expected mediocre performance, both in terms of velocity (sub BP "envelope") and accuracy.

I believe I've posted this elsewhere but I only got around 950 fps with the traditional "suggested" loads of IMR SR4759 or IMR 4198. H4198 did no better.

I find it interesting that Lyman shows 34 gr. of IMR 4198 (slightly faster than H4198) in the .45-70 with a 385 gr. bullet at less than 18K CUP but Mr. Pearce stuck with the old standard of 26 gr. 4198 under 457122 in his .45-70 work up. I believe he actually used the same or higher charge in the .45-60! (don't have the book next to me at the moment)

I was just doing a comparison of the .45-70 Trapdoor (sub 18K CUP) and .45-75 loads using IMR 3031. Again, we seem to stick to starting loads in the .45-70 (or less) when using the same powders and bullets in the .45-75. I can't find any reason why.

In most situations it is enough to say that a particular launching system/firearm can handle pressures of X CUP or PSI in a particular cartridge and then stick with those pressures. It would seem that this simply method would apply to the 1876. Anecdotal "evidence" purporting to support the contrary view that the 1876 is somehow susceptible to different pressure curves actually uses instances of excessive pressures brought about by using overly "optimistic" loads. In old, original firearms, the condition of the material used in the construction of those firearms and it's actual condition after 100-130 (or more) years of use is an absolute mystery until the gun is destroyed because there is no consistency in the materials. It is therefore difficult if not impossible to address this variable.

However, I've been circumspect in my review of the Lyman 49th Ed. data because I've noted what I consider to be a tremendous number of typos in the narrative/article portions of the manual. A small thing but if these guys are relying on spell-check rather than a human proof-reader I don't know that I fully trust the rest of the manual. If I don't trust the manual then why have it?

As to having "kabooms" in guns, we've all seen photos of modern Marlin 1895, Mike Venturino's friend "Shrapnel"'s '76, a recent photo of a Ruger SP101, etc, ad naseum. These all prove that ANY gun can be brought to the point of catastrophic failure due to faulty reloading or perhaps shooting practices. If even modern designs constructed of modern materials can fail due to improper reloading practices, I can only say that you proceed at your own risk.

Now there is nothing wrong with risking yourself if you understand the risk. There is, however, no reason to risk the well-being of others either by handing them unproven reloads to shoot OR by testing loads with them sharing the firing line at the range. Consider the safety of your fellow shooters before you fire even one round.

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