A Swedish Rolling Block comes back to life

Andy

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I love the old big bores and have messed with a Snider Cadet Carbine, various Swiss Vetterlis, a few Mauser 71 and 71/84's, and a Dutch Beaumont. I also love Swedish stuff, so it's only natural that I'd buy a Swedish Rolling Block and that I'd shoot it as soon as possible.

I bought this M1867-74 from P&S Militaria a couple of weeks ago. As always, it was exactly as advertized and was shipped well-packaged and without delay. Everything matches, and I have a replacement Unit Disk on its way. I took it completely apart and cleaned it, taking particular care to free up the firing pin which has seized somewhat. A seized firing pin in a Rolling Block is a very bad thing as if protruding, it will be forced against the primer when the breechblock is closed - leading to possible unexpected firing with the hammer back and breechblock unsupported. It freed up nicely after some work.

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This M1867-74 is chambered in 12.7x44R, but after taking a chamber cast with Cerrosafe, I discovered that I was fortunate to have one with a chamber generous enough that I can use Starline 50/70 Government brass, which required nothing more than trimming down to 1.715" and reducing the rim to 0.625", rather than a few more steps with 348 Win brass which is the usual process. The bore slugged to 0.515" (50 cal) and these guns have very aggressive lands which rise to 0.484" in my gun. Naturally I use cast bullets, and the Lee #90255 is perfect, dropping a 0.515" bullet at 430 grains using my mix of Wheelweight + 2% Tin. I lube with Alox. Lyman 50/70 dies did the rest. Loaded OAL was 2.310"

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As for loads, this was originally a Blackpowder round, but as with all my rifles, I use Smokeless. Some BP guys wet themselves over the notion of using Smokeless in such rifles, but it is completely safe if done with care as with any loading procedure. I tried five different powders and had some good results:

Unique - 12.0 grs - 1000 fps - good grouping
H4198 - 28.0 grs - 1150 fps - good grouping
XMP5744 - 28.0 grs - 1200 fps - very consistent MV's, but the poorest grouping
H335 - 40.0 grs - 1050 fps - inconsistent ignition, very large MV variation, poor grouping (too low a charge weight?)
Pulled Swede - 50.0 grs - 1250 fps, consistent MV's, good grouping

No fillers were used. The surprises were the XMP5744 which is supposed to be THE BP substitute, but it put shots all over the target, and the H4198, which I had expected less from. H335 might not be suitable for this cartridge at the load densities required to stay at pressures the action could handle (<20K psi) - I could have gone higher (say to 45 grs) and might some day, but 40 grs did not work. Unique is always a good choice, and the Marstar Pulled Swede (from the 8x63) has been my go-to powder for all the Milshoots, and I have found it to be an excellent BP substitute. Its Burn Rate is close to IMR4064, and a full case of Swede gives velocities similar to what the original full case of BP produced. You get some "clinkers" (burnt powder particles), but they do nothing to affect accuracy. The other surprise is that the gun shoots 12" low (Milsurps most commonly shoot high), so the fix is easy - set the sights for 180 yds (this one goes 120, 180, 240 and 300).
 
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I'm wondering how Hodgdon's Trail Boss would fare in that cartridge.
PP.

I suspect that it would be fine. I wouldn't go much above 10.0 grs and would not expect much more than 1000 fps. I have some and it's "fluffy", but would still fill less than 1/2 of the available space, and since Unique burns so reliably with such a small load, there's no real advantage to gain from its case filling properties (low density). It's quite a fast powder, and we all know that for a given MV, the slower the powder, the lower the pressure. I'm willing to bet that 1000 fps from Trail Boss would yield the same pressures as 1300 fps from the Swede. Other than its case filling properties it's known as a very good powder for cast bullets at low velocities. If I wanted to do up a load at say 700 fps, I'd quickly choose it. I have a low velocity load with it for my 44 Mag and it works quite well.

I still have Aliant 2400 and SR4759 to try, as well as a wad above the H4198 load and 52.0 grs (full case) of the Swede. When all's said and done, I suspect it'll be the Swede I stick with.
 
44 Maggie

Thanks Andy, it's been a very interesting thread.
BTW, can you shed more light on your 44 Mag slow load? I have some people to train on the single-action revolver and I'm looking for a good, tame load for beginners.
PP.:)
 
Glad to help, but after this I'll try to steer us back to Rolling Block issues. ;)

I took one load from the IMR site and another I contrived. Trail Boss is designed for low velocity cast bullet shooting. Trying cast loads with jacketed can get you bullets stuck in the bore, and trying to attain higher velocities (the same as you can routinely get with other powders) can result in over pressure situations.

I have used:

- 240gr cast over 6.0 grs to get about 875 fps from an 8 3/8" barrel; and
- 310gr cast over 7.0 grs to get about 750 fps.

If I was to try it in the Rolling Block I’d start with 10.0 grs with the 430gr cast and adjust to get about 800 fps.
 
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Thanks!
In your Rolling Block loads with Unique and 4198, did you make use of standard or magnum primers? the fact that you got some unburned flakes can be attributed to the lower pressures but did you get much powder soot?
And in that case, do you think magnum primers could help?
PP.

PP.
 
I used standard primers in all loads. No flakes with Unique, but I got them with all other loads. Like I said, they had no negative effect, unless they fall back and get into the chamber, in which case they could impede loading. It's not unburnt powder, rather soot like you described. I've examined them, and they crumble when handled and won't burn under a flame. The pressure is very low, and they just were not expelled from the 36" barrel.

I doubt that Magnum primers would change that, but they sure would elevate pressure with little increase in MV.
 
I like 50.0 grs of pulled 8x63 Swede powder under the Lee 430gr cast. Gives about 1225 fps and a nice 10 shot group. :) My load development work is done. I am confident that I will beat several Garands and No 4's at the next Milshoot, even single loading as I must. ;)

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This is my effort. It likes 24grns of XMP 5744 and 500 grs wheel weight cast bullets that are two months old or older. I put scopes on everything.
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Thanks. It is a nice rifle but I can't claim credit for it, the only thing I did was the bluing. Mike Magee the gunsmith and rolling block nut from Gull Lake Sask rebarreled it and supplied the wood. He also tweaked the trigger. It was a stock 1879 Argentinian contract rifle when I got it, but I cracked the barrel and could not find another one so I thought I might as well make use of the action. I have shot over 2000 rnds through this rifle and it is very accurate with the right loads. The crappy trajectory lets it down, it's like a rainbow.
 
Thanks. It is a nice rifle but I can't claim credit for it, the only thing I did was the bluing. Mike Magee the gunsmith and rolling block nut from Gull Lake Sask rebarreled it and supplied the wood. He also tweaked the trigger. It was a stock 1879 Argentinian contract rifle when I got it, but I cracked the barrel and could not find another one so I thought I might as well make use of the action. I have shot over 2000 rnds through this rifle and it is very accurate with the right loads. The crappy trajectory lets it down, it's like a rainbow.

That can be expected from any heavy weighted gun.
Like howitzers. :D
 
Time to get this thread alive again!! I just got my 12.7 in the mail!!! Popped a 50/70 brass in and no joy. Full length sized it and voila perfect fit rim and all. How important is it to trim to length? Any reccomendations on a starting load in smokeless? I have some 4198 on hand and lots of bp. My bp load will be 60 grains with a 450 grain lee bullet over top. Can't wait to shoot her.

Cheers
 
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Time to get this thread alive again!! I just got my 12.7 in the mail!!! Popped a 50/70 brass in and no joy. Full length sized it and voila perfect fit rim and all. How important is it to trim to length? Any reccomendations on a starting load in smokeless? I have some 4198 on hand and lots of bp. My bp load will be 60 grains with a 450 grain lee bullet over top. Can't wait to shoot her.

Cheers

See post #1 for some smokeless loads. You can safely use maximum 45/70 Trapdoor loads. You can go higher, as the action of the Rolling Block action is stronger than the Trapdoor, and the cartridge and bore size is larger than the 45/70, but why would you? 45/70 Trapdoor loads give you good mild, useful loads.

You should trim to length. If you don't, once a bullet is seated it won't chamber, and if it is forced in, the rifling cold pinch the neck and cause high pressures. I'm surprised that you didn't need to reduce the rim diameter - perhaps it has been rechambered to 50/70. Only a chamber cast can confirm, and any decent gunsmith can do one for you.
 
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