Measuring the caliber?

[FiremarshalBill]

I have an Austrian Lorenz rifle musket that was dug up in the Arizona desert near an old Butterfield stage station that had been abandoned in the late 1880s. Because of the very dry climate in the area it is in remarkably good condition. Everything works and it is probably fireable (though I never have). When dug up, it was cocked and loaded and had apparently been leaned (or fallen) against a sand bank that eventually collapsed and covered it completely. By 1970 when it was dug up, the tip of the barrel was only a few inches below the surface and enough water had seeped through the soil to pit the top 2-3 inches of the inside of the barrel which makes it hard to determine the exact caliber by just looking down the muzzle. My question is, how do I determine if the caliber is .54 or one of the Lorenz rifles bored out to .58 caliber? Seems I've read somewhere about pushing a plug of some sort (lead? clay? plastic? soft wood?) through the barrel and then measuring the caliber from that plug with a micrometer? Any suggestions what to use as a plug? Should it be pushed through from the muzzle end or should I remove the threaded breech block and push a plug through from that end?

 

[ranger326]

Hello from Tennessee!

Somebody will be along to help, but I just gotta see pictures!!

d

 

[Old Hickory]

To "slug" the barrel by pushing an oversize soft lead slug through, you would need to remove the breech plug and push the slug the entire length of the barrel which would give you "groove" diameter. Being a muzzle loader, you want "land" or bore diameter, that is the diameter of the bore before rifling the depths of the grooves. This is best accomplished with pin gauges for precise diameter, but since you just want basic caliber you can simply measure with a caliper land to land if it has an even number of grooves, (2-4-6), an odd number, (3-5-7) and it won't work. Probably the simplest thing would be to google a fractional to decimal conversion chart and carefully measure across the bore with a ruler and convert to decimal. Or get a .58 bullet and see if it goes in.

 

[knoet holgerson]

droped a dril in the barrel, cal 58 is 14,7 mm, en when it is stuck ,use a compressor to get it out

 

[FiremarshalBill]

Since the muzzle end of the bore is corroded for the first 2-3 inches, could I press the slug into the barrel from the breech end to say, 1/2 to 3/4 of the way up the barrel, and then push it back out from the muzzle end to get an accurate inside barrel diameter? I would have thought the difference between .54 caliber and .58 caliber would be more obvious, but without actually measuring, it looks larger than .54 but smaller than .58. Is there anything I can use besides a lead slug to simply determine if it's a .54 or a .58?

 

[Jobe Holiday]

The Austrian Lorenz was actually more like 0.55 caliber, so yes it is bigger than a 0.54 and smaller than a 0.58!
J.

 

[Don Dixon]

The bore diameter of an unmodified Muster 1854 System Lorenz rifle is 13.9 mm/.547 inches; rifled with four lands and grooves. However, the first six to 6.5 inches of the bore at the breech received a tapered relief of an additional 0.025 inches/0.635 mm. This was called the Ründung [drop or fall]. Relieving the lands and grooves at the breech permitted the bullet to expand and then be compressed, creating a progressive rifling system at the breech.

Since the rifle has been out in the elements so long, pulling the breech plug is likely to be problematic. I would get a long 14mm drill bit. If it either won't go into the barrel or won't go any further than the first 2-3 inches from the muzzle then the rifle is in the original caliber. If its loose, then you have .577, .580, or perhaps larger. Some of the rifles that were re-rifled in Belgium are as large as .600.

Regards,
Don Dixon

 

[DixieRifles]

Probably the simplest thing would be to google a fractional to decimal conversion chart and carefully measure across the bore with a ruler and convert to decimal.

The difference between .547 and .577 is 0.03 or approx = 1/32 inch.

The bore diameter of an unmodified Muster 1854 System Lorenz rifle is 13.9 mm

I was wondering why the metric system was being introduced to this discussion---but then I realized this is a European gun.

My question is what happens to the bore ID if it is exposed and corroded? Would the rust built up and thereby reducing the ID? So inserting a plug down the barrel will only measure the smaller diameter of the rusted end.

This may not work in this application, but one way to check dimensions or surface finishes is to take an impression using clay. Years ago, I found a clay material that can be easily baked to harden it to a permanent set. Then you can get really fancy and use something like a sealant or a 2-part epoxy and a releasing agent.

 

[originalrebelyell]

I would not suggest pulling the breech plug on the gun if it has been out in the elements that long, its likely to be rusted frozen solid in place. You might do more damage to the breech end of the barrel and breech than it is worth.

 

[FiremarshalBill]

Actually, the threaded breech block was fairly easy to remove and I have unscrewed it a couple of times. I think the dirt/sand jammed in the muzzle might have actually kept very little, if any, water from running down the inside of the barrel which still has some shine to it.

As Dixierifles mentioned above... Would the rust built up and thereby reduce the ID? Or would the pitting caused by moisture in the top few inches of the barrel increase the ID?

The difference of only 1/32 of an inch (between .54 and .58) has really got me curious now. I know both sides used this particular model, but since the Federal Government had the arsenals and the capacity of re-boring a .54 caliber barrel to use the more common .58 caliber ammunition, and the Confederacy didn't really have that capacity, determining which caliber it is might at least suggest which side it was originally issued to?

 

[Don Dixon]

The Federal Army imported both .54 and .58 caliber System Lorenz rifles. They also rerifled some of the long range sighted .54 caliber weapons to .58 caliber. The Confederate purchases were in. 54 caliber, but the Confederates captured and reissued large numbers Federal weapons. So, you can't tell who used it just based in the caliber.

Regards,
Don Dixon