Deciphering the Caliber of Your New/Old Drilling Gun

By Bob Shell

Drilling Gun
Close Up Look at Some Drilling Gun Hammers

Apache Junction, AZ –-( For those who might not know a drilling is a three-barreled gun. Usually, the top two barrels are shotguns while the bottom is a rifle.

Many of the older drillings are chambered for 16 gauge though the 12 shows up fairly often. The only question with them is the length of the chamber and if it is a black powder or smokeless piece. If it has Damascus barrels you should stick to black powder after making sure the gun is safe to shoot. Also, many of them have 2 & ½” chambers as opposed to the more modern 2 & ¾”.

The fun begins when you want to shoot the rifle barrel. Frequently the barrels are not marked and each maker chambered his guns for unique cartridges designed by his company.

That is where advanced ammo making and reloading techniques come in handy.

You have to have a good understanding of these guns to make safe and shootable ammo. Some are made back in the last quarter of the 19’th century to the early years of the 20’th. You should ascertain that the gun is sound and safe to shoot. If not sure consult a competent gunsmith beforehand. Many of the drillings were made in Germany which generally guarantees good quality. Some made elsewhere may or may not be so good. They are complicated and expensive because of the firing mechanisms. You generally have two triggers to fire three barrels which necessitates a lever on top or the side to determine which barrel you want to fire. That involves extra parts and fitting which adds to the cost.

An advantage to owning a drilling is you have two guns in one. You have a shotgun or rifle at your command. Most of the rifle calibers range from adequate to good large game cartridges though there are exceptions. I ran into a 22 Hornet barrel once.

11.03 11,03x50R Scheibengewehr and 11 X 60 Mauser
Some Drilling Calibers include 11.03 11,03x50R Scheibengewehr and 11 X 60 Mauser (center) Rounds

After you determine that it is safe you need to figure out what the chambering is. Usually, the best way is to do a chamber casting. By far cerrosafe is the best product to use. It melts at low temperatures, around 170 degrees making it relatively easy to use. It can be purchased at Brownells or Midway. After you clean the chamber you put a plug in the barrel about ½” in the rifling which will also give you the bullet diameter.

You should have a tin type of container that you can melt it and pour into the chamber. It cools rapidly and after a couple of minutes you can tap it out. You should have a cast of the chamber and rifling. Then you have to find which case you will use to form the brass. This is where some knowledge is essential to make good cases. If you are unable to do this, the cast can be sent to a custom reloader to make some ammo for you. Be prepared to pay a steep price for that service.

Original 11,03x50R Scheibengewehr round
Original 11,03x50R Scheibengewehr Round

The gun I used for this piece was made by J. Reeb who made guns many years ago in Germany. It is a well-made piece though there is no engraving that is found on some. Typical of the day the hammers are hard to cock and the triggers have a heavy pull. I did a chamber cast and determined that it is an 11 X 60 Mauser round but 3/8” was cut off of the neck. I made a test round and it fired perfectly so I trimmed a bunch of cases for working up a load & the owner wants to hunt with it.

It has provisions for a claw mount so when he has one custom made he can use a scope if desired. Since it shoots an 11 mm bullet big game at moderate ranges is a viable option. The rifling is good so I expect some good working accuracy from it. Naturally, we want to shoot this gun.

The customer doesn’t want black powder which brings up another challenge. Is it safe to shoot with light loads of smokeless?

Through various ways, I determined that it was. Since I have worked with similar guns and calibers in the past I felt on safe ground working up a couple of loads. I have worked with a couple of 11 X 60 Mausers one was a double rifle that is quite old. Since this cartridge has a shorter neck I reduced the powder charge by a few grains from the Mauser loads. The process is called extrapolation and should be attempted by very experienced reloaders only.

Test Firing the Drilling Gun
Test Firing the Drilling Gun with Custom Made Rounds.

I am happy with these loads as they give plenty of velocity without straining the old gun. These loads would be very adequate for deer and black bear at woods ranges. Once a scope is mounted it will make a nice addition to any hunting rifle collection. The iron sights are not that good. A little research from a German friend has probably come up with the proper name for this cartridge. It is a 11,03x50R Scheibengewehr an obscure round from the 19’th century. The picture closely resembles the fired cases I have.


31 X 5744 – 300 grain cast – 1615 – very consistent

37 X IMR 4198 – 300 grain cast – 1698 – ok

27 X 5744 – 370 grain cast 1388 – very consistent

33 X IMR 4198 – 370 grain cast – 1517 – ok

It’s always a great opportunity to get an old gun to shoot well.

Rear View of the Drilling Barrel
Rear View of the Drilling Barrel

About Bob Shell
A Custom Reloader of Obsolete and Antique Ammo, Bob Shell, writes about the subject of Guns, Ammo, Shooting and Related Subjects. Visit:

Bob Shell

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mike laird

Hhave a 1936 drilling marked 7.8×57 that will not camber a 8×57 more than 1/4 inch as the 8×57 is too big to go in the chamber any help would be good


8*57 (7.92*57) comes in at least two diameters: .318 and .323. You may be trying to put a .323 round into a .318 chamber.


I’m arash and living in Iran isafahan 

I’ve got a gun I’m too old and the caliber 11 was wanting you can help me
I need this a carriage caliber 11 please help me
Waiting for u email



I’m arash and living in Iran isafahan 

I’ve got a gun I’m too old and the caliber 11 was wanting you can help me

SFC Ralph Denton USA (Ret)

Where can I purchase 2&1/2″ 16ga shotgun shells to shoot in my Damascus barrelled Drilling?

Gerald Keller

Hi – Have you ever heard of a caliber called 25 Win? I am being told that a rifle I am interested in was re sleeved to thei caliber from 7.7? When I look up the 25 Win I see – 25 WSSM, 25-20, all sorts of things. The guy insists its 25 Win. Do you know of a 25 Win? This is for a Bock combination gun. – Thanks!!


Re. Guy. My drilling is also stamped 7.7 x 57. (16 x 16) So close to ah 8mm Mauser.
I’m guessing I’m going to have to have a good gunsmith do a mold of the chamber.
Mold is not the right word. I forgot the correct word. But You know what I mean.
Buffalo Arms said they can then figure it out for me.
I’m not the interested in shooting my drilling. I just want to know the caliber.
Let me know if you get an answer mike

guy R. Mundale

Greetings;…I own a 1930’s+/- German Waffen Weib 16ga. over 7.7mm rifle. I am attempting to determine exactly what kind of cartridge this is. I have not been successful. I need some direction/info/advice. The chamber appears to be tapered. It is stamped nitro for all chambers. Bores are “as new”….Thanks for the time to assist me…Guy

larry krumrine

looking for 6.5 x 70 r loaded ammo.

also looking for 11.0 mm loaded ammo.
this would be used in an Austrian cape gun.
I think it was made in 1898