Making cases for 11mm Murata

[tiriaq]

Acquired a Type 18 rifle with what appeared to be a shootable bore. According to Donnelly, a .450 basic case can be used. Not much more available than Murata ammunition. Asked a very experienced reloader, he suggested .348 Winchester, although it is a bit short. That doesn't matter much, given the longish neck. .348 is easy to find. Primed cases with WLR primers, charged with 12gr 700X (had it readily available), filled cases with rammed cornmeal, sealed with wood glue. Cases fireformed beautifully, extracted easily. None lost, even though I had not annealed the necks. Added bonus is that the cornmeal seems to have scrubbed the bore a bit.

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[Patrick Chadwick]

Added bonus is that the cornmeal seems to have scrubbed the bore a bit.

Which is why it might not be a good idea to make a habit of using such material. Fine for fire-forming, but not as a filler for regular BP loads - it might just be wearing the corners off the lands...

But congratulations on getting a rare old banger going again!

Patrick

[tiriaq]

Agreed. I had hoped that the granular nature of the cornmeal would remove some of the fouling in the barrel, but a regular diet would not be a good thing.
In a recent Double Gun Journal article there is an analyisis of different fillers used in smokeless for black loads in a BPE double rifle, and the effect on pressures. Strain gauges were used to record pressures both near the base of the cartridge and at the mouth. There are reports of some fillers causing ringing at the chamber mouth, and the author was looking for pressure spikes (which he did not observe). Plain cotton batting appears to be as good as anything else.

[tiriaq]

While I have not yet slugged the bore on this rifle, an 11mm bullet for a 71/84 Mauser thumb seats nicely in the fireformed case.

[Patrick Chadwick]

... an 11mm bullet for a 71/84 Mauser thumb seats nicely in the fireformed case.

If that bullet is a finger/thumb push fit in the case, and so does not expand the case so that it jams in the chamber, then you have IMOH the ideal setup for BPCRs, and you case will last and last and last...no resizing at all!

All you need to do is make a mark on the rim so that you always have the same case orientation when you push the case into the chamber (if the Murata will let you push in the case and then close the bolt) and you will have a "BPCR-benchrest" setup.

When are we going to see a test target?

Patrick

[tiriaq]

Have to install a rear sight before any shooting. I suspect the chances of locating an original sight are very low, but I can certainly adapt a sight. The sight base is secured with two screws, no solder, so installing a sight with period appearance will be straightforeward.

[tiriaq]

Have installed a rear sight from a Krag rifle. One screw plus double sided tape. Should serve the purpose, no alterations to either the rifle or the sight. A case with an 11mm Mauser bullet inserted chambers freely, and the rifle fired normally. Have a couple of boxes of fire formed brass now, so will be assembling rounds and testing the rifle soon.

[Patrick Chadwick]

... and show us the results.

BTW, if you don't want to be cleaning the bore after every shot, you will need about 1/2 cc of lube behind the bullet to keep the fouling soft enugh to be cleared out by subsequent shots.

A load made up of Swiss No.4 plus overpowder wad plus 0.5cc of lube plus the bullet seated to be about 1mm off the lands will do nicely for this generation of rifles. Since the bullet is also lubricated in the grooves, a wad between the lube wad and bullet is superfluous.With the lube wad, it should not be necessary to use any filler.


Patrick