Swedish 12.7 Rolling Block

Rochelle

I have put together all the materials and etc. to start reloading the old Swedish 12.7 Rolling Block. I want to use a black powder subsitute to limit the presures in this old gun. What I would like is some powder I can use and treat the gun like I would using a normal smokeless powder. I am not intrested in taking it to the bath tub after shooting it.

DaveF

I've shot this caliber a fair bit using 12gr. Unique and the Lyman 515141 bullet cast soft and sized 0.512".
It's accurate in my rifle, which is a tight Carl Gustaf dated 1875, but as with anything pushing a 135 years of age, "there ain't no guarantees", so I usually use black powder.
Regards, DaveF.

44caliberkid

You can use American Pioneer Powder or Jim Shockey's Gold. It leaves no reside buildup, load by volume like real black, mild pressures, and cleans with one pass of a wet (water) patch.

mbsams

You don't need a bath tub. Use the cheapest rubbing alcohol you can buy from the drug store. Shoot your gun with real black powder or pyrodex and at the end of the shoot swab out with the alcohol and oil lightly. Been doin' that for 40 years, no problemo!

tbn95

I would try Trail Boss powder.It is used for cowboy shooting for lower velocity. I have used it in 45-70 with good results.

Billy Thunder

I shoot mine with real BP or 12.5 gr. Unique w/ a 450gr bullet.
No need for a bathtub soak with BP. It's a breeze to clean with the open breech. I use a mixture of BP Solvent and Canola oil for cleaning and swabbing after a few shots.

Rochelle

This Rolling Block is getting to be a pain in the post area.

All the advice I got says "fire form 348 Winchester cases, they'll work fine" Rim is to small for the extracter!! The extracter fits the chamber wall just fine. Then I was told "Maybe your rifle has been reamed to 50-70, a lot were". Bought a new case, Rim area in the rifle isn't deep enough to accept the 50-70 rim.

Does amy one have a 12.7X44 case that would take a micromenter to the rim and post the measurments. Diamenter and thickness, metric or ASM, I don't care. I can work from there.

Thanks Dan

DaveF

Because the .348 brass is tapered, and is also smaller in diameter at the base than 12.7X44R, when fire-forming the cut down .348 cases to make 12.7X44R, apply a double wrap of 5/8" wide masking tape wound around the brass immediately in front of the rim. This will add enough diameter to hold the brass centered in the chamber and allow the extractor enough contact with the rim to pull it back out after firing.
For the second loading in the now mostly fire formed brass, I replace the 5/8" masking tape with another double wrap of tape cut to only about 1/4" width, and fire it using a regular load. This completes the case forming, and the tape is then discarded.
I sounds like a PITA, but it does work.
Regards, DaveF.

Rochelle

Thanks Dave, that explains & will help a lot, I would still like to know the dementions of the orginal case.

I have found several sites that explain the Swedish had a diferent way of measurment back when and how they didn't use the metric system back when, BUT nobody seems to know what the measurements are today. Kind of makes a feller wonder about that.

Thanks again Dan

Billy Thunder

I've owned several 12.7X44's and I shoot mine with slightly modified 50-70 brass.
I've noticed the chambers on mine are all a little different. The one with the 'loosest' chamber will almost accept a 50-70 cartridge.

I have yet to encounter one that will not accept the rim thickness. I have needed to turn down the diameter of the rim for some chambers. A 50-70 case is usually a bit tight near the 'web' area just above the rim and will often give the impression that the rim will not fit. A quick test to see if the rim will fit, without the web area interfering, is to insert the case rim first (case backwards) to fit just the rim into the reccess

Rochelle

I have noticed the case dimensions for the 50-70 are almost identical. a quick turn in a drill and a file and they fit perfect. When fire forming the 348 cases I noticed a large space between the end of the 44MM case and the start of the rifling. I have ordered a small lot of the 50-90 cases and will trim them down until the bullet is just scored touching the rifleing. That should improve the accurate a bit.
I still haven't found a reference to the orginal case dimensions. I guess that is one of those things that is lost to history.