Drilling Out Chambers

[nkbj]

I recently acquired a 6" barrel .31 with undersized rough as cobs chambers and have gotten a size "O" (that's 0.316") drill bit to try out, figuring that's worth an initial try before going the next step larger in either drilling or reaming.

Question: Have any of you drilled as opposed to reamed chambers with satisfactory results?

 

[Artificer]

Really, REALLY BAD Idea to try to drill the chambers. I can almost guarantee it will screw up at least one or more chamber/s.

My strongest advice is a job like this should be done by a machinist or gunsmith.

Gus

 

[bpd303]

I have to agree, don't try a drill bit in chambers. I know because I tried it years ago when I was young and dumb. Still have that cylinder to remind me.

 

[crockett]

I don't see any harm in polishing up the chambers a little but the drilling- I agree. Have you shot the gun yet?

 

[hawkeye2]

First I am assuming you have a reproduction. If it is an original leave it alone, you'll hurt its value. You could probably buy a new cylinder for less than you can have that one repaired. Is it an 1849 repro? They are rare and quite nice with a 6" barrel

You probably will ruin the cylinder using a drill on it no matter how careful you set it up and proceed. The cylinder should be honed instead and even that is kind of an iffy job out in the garage with a drill press.

 

[kaintuck]

The bit will bite into the steel..... :shocked2:
Maybe a hand reamer will survive.....on a drill press, w/o the power on~~~everything by hand...
Take it to a machinist maybe.....

Marc

 

[Artificer]

Your question got my curiosity piqued and we need a lot more information to really help you.

1. What is the model of revolver you have?

2. What manufacturer’s name is on it?

3. Is it blued or stainless steel?

4. Is it a reproduction revolver?

5. Does it have a serial number on it on the frame or maybe the bottom of the grip frame?

6. Not sure what you mean by the cylinder holes being undersized. Those holes have to be sized so the ball will form a tight friction fit or they will come loose in the cylinder when you fire off another cylinder. If you ream out the holes so they load easily, the balls will work loose as you fire the other balls in the cylinder and make the cylinder unserviceable and or unsafe.

7. Not sure what you mean by the cylinder holes being rough as a cob. Are the holes poorly machined? If so, that would be a warranty repair if the revolver is still under warranty. Are the holes seriously rusted or pitted from rust?

OK, first I will give you the worst case scenario.

If the cylinder holes have serious machining problems and the revolver is not under warranty, you may have to buy a replacement cylinder to be able to fire the revolver efficiently and/or safely. IF a replacement cylinder is available (and it may not be if it is an older reproduction), it is going to cost between $ 80.00 ”“ 95.00 plus shipping. That is going to be less expensive than having the holes reamed out. However, some fitting MAY also be required and that will cost more. Most gunsmiths won’t do this kind of work on these guns as the work can easily add up to more than the cost of a replacement revolver with the parts and labor combined.

If it is an older Navy Arms or Euro Arms pistol, Euro Arms is out of business and Navy Arms probably won’t have a replacement cylinder ”“ if the cylinder really is machined incorrectly or seriously screwed up. I would suggest contacting Taylor's & Company, Inc. in that case as they have been able to get repair parts for Italian Revolver replicas that few or no others can or will. Have the revolver in your hands when you call them so you can ask questions. Oh, I am NOT involved with them other than I have purchased a WHOLE LOT of parts from them over the years to repair Civil War guns. http://www.taylorsfirearms.com/contact-us/

The least expensive, but VERY time consuming method to clean/polish the cylinder holes will require these items:

1. One or Two .30 caliber bore brushes. Military bore brushes will last longer and be a better value to do this work.

2. One section or piece of an M10 .30 Caliber military Cleaning rod. You will screw the bore brush into this and it will act as a holder that you can put in an electric drill.

3. A ¼” electric hand drill.

4. A bag of OOOO steel wool.

5. A can of Kroil Oil or maybe better still, PB Blaster Oil.

6. Cold Blue if the gun is blued and not stainless. I most strongly recommend Brownell’s Oxpho Blue. http://www.brownells.com/gunsmith-...uing-chemicals/oxpho-blue-creme-prod1108.aspx

Screw the bore brush into the cleaning rod section and center/tighten the cleaning rod section in the ¼” electric drill. Unwind one of the 0000 steel wool pads and tear off some to wrap around the bore brush. Run the drill slowly to wind/wrap the steel wool around the bore brush until you have enough around it for a somewhat tight fit in the cylinder holes. Put oil on the steel wool and slowly run the drill and start it in the hole. After the steel wool wrapped brush is in the cylinder, you can run the drill faster to polish the cylinder. As the steel wool gets worn down, wrap more around it to get a tight fit in the cylinder hole.

Clean/polish every cylinder hole this way. You won’t take out pits, but you will smooth it up a lot and won’t hurt the chamber holes. Clean each hole thoroughly when done, degrease with Alcohol or Acetone, use the Oxpho Blue to resist more rusting and oil the chamber holes to keep them from rusting more, then wipe each hole dry.

Gus

 

[44-henry]

If it absolutely had to be done I would find someone with a metal lathe that can make a piloted reamer. A D type reamer with a pilot that will fit the cylinder perfectly would do the trick since we are only talking about shaving off a few thousandths and this style reamer doesn't take more than 10 minutes to machine with a suitable piece of drill rod handy. The actual reaming could than be done with even a hand drill.

The D reamer involves turning the pilot to about .001 smaller than cylinder bore size and than step up to the desired diameter of your cylinder. Following this exactly half the diameter is ground away leading slightly into the pilot. Following this the reamer can be hardened and tempered and finally honed. I have used these for many applications and they do work and will cut a smooth hole.

That being said I would agree that more info is needed before proceeding.

 

[Vaino]

Using a drill as a reamer is fairly easy.....the drill "point" has to be a radius {bullet nose} instead of the normal angled drill point. Have done this many times when the hole wasn't a standard reamer size. Ensure that the radius has proper cutting or lip clearance. Also the cylinder has to be held tightly.... preferably in a "V" block.

Low RPM, slow feed and plenty of cutting oil will get the job done nicely......Fred

 

[nkbj]

To all,
It's a very old FIE of surprising good quality and essentially new in the box. While well taken care of it's apparently not been used because nobody could hit the barn with it half the time.
The insides of the chambers are bore diameter and rough, as though drilled and never reamed. In short, it's a great revolver except, well, unfinished in this particular aspect. At this time, as stated, I'm looking at drilling to .316" to see if the .310" bore will shoot accurately at that chamber diameter. If not then I can take it out to a larger diameter.
As stated, the question was, has anybody tried just using drill bit rather than reamer. What kind of results did you get.

And yes, I'm very tempted to send it out rather than screw it up. However, even though the chambers will have to be enlarged, a smith will end up costing more than was paid for it!

 

[LRB]

Gus, many of the older repros came with under sized chambers that need to be reamed out to get good accuracy. One simply uses a larger ball after reaming for a tight fit.

 

[LRB]

That's good to know Fred. Thanks.

 

[crockett]

The big worry is reaming off center and making things worse- or at least I THINK that would be the big problem. If what needs to be done is just cleaning up some rough machining- well I'm not sure that is the same thing as reaming. To me reaming entails setting everything on a drill press, and then using a drill bit and actually enlarge the current chamber with metal shaving coming out of the drilling, etc. Potential troubles are reaming off center (side to side) or clamping the cylinder at a slight angle (run out). You would not use a normal drill, there are special reaming tools (I use one in making folding knives) and I don't know if you could get the correct diameter. In any event having to do this with all six chambers increases the chance of a botched job, or at least it would for someone like myself.
Now I am one of those folks that is always looking for the easiest way to do a job, using hopefully - a foolproof method.
Here is an idea and I hope some of our more experienced metal workers might comment because I'm not sure it will or will not work. As I said, to me I think the main concern is reaming off center. There is a tool called a range rod that is used with modern revolvers and it is precision ground, it is used to see if the chambers on a modern pistol are properly aligned. The range rod goes down the muzzle and should slide into the chamber without any "bumps". If it bumps- the alignment is a little off.
Well, if what you really want to do is a polishing job- not shaving off more metal, I'm thinking of some sort of range rod with a jag on the end, where the jag has been rolled in lapping compound. If you are not familiar with lapping compound, it is an abrasive paste. Some times a cast slug is made of a bore and the cast rolled in lapping compound. There are a variety of grits that are used/available. It seems that lapping ought to work but I might not be seeing all the in's and out's on that idea. The big benefit is the range rod insures the lapping in the chamber is done on center with the bore.

 

[Zonie]

As several others have said, using a standard drill bit to enlarge the chambers will get you in trouble.

The two flutes cutting edges and the rapid twist will bite into the steel and attempt to pull the drill bit rapidly into the hole.

If the cylinder isn't held tight enough it will start flailing around damaging itself and everything in sight.

If you do clamp the cylinder securely there is a good chance you will damage it by crushing it out of round.

Even if the drill bit doesn't grab the part it will probably produce a hole that is about as rough as the ones in the cylinder now.

The proper way of enlarging the holes is by either reaming or honing.

Reamers typically are designed with straight flutes that won't pull the tool into the hole.
Although the cutting edges on the front of each flute will bite into the steel they won't pull the tool into the hole.

Reamers are designed to enlarge a hole about .005 (five thousandths) of an inch of material, total.

Keep in mind that although each cutting edge of the reamer is only cutting off .0025 thick chips there are at least 4 and often 6 flutes at work so some real power is needed to drive it.

Reamers tend to be self piloting but they do need to be kept square with the hole while they are first starting to cut. After they do, they will follow the hole quite nicely.
Due to this tendency, reamers used in drill presses are rarely forced to a fixed position. The floating drive head allows them to follow the hole freely but transmits power to them.

Using a crossing T drive handle similar to a large tap wrench will also accomplish this when the hole is being hand reamed.

As I mentioned, reamers are designed to enlarge the hole only about .005, if more enlargement is needed either several different reamers are needed or an adjustable reamer is required.
Most adjustable reamers are quite a bit larger than the .310- .316 size we're talking about.
Reamers, properly lubricated and used will produce very good, accurate finishes.

Now, as I mentioned, honing is often used to enlarge holes and to improve the surface finish.

Honing is a grinding process so lots of lubrication is needed to wash away the removed material and the grinding material off of the tool.

It just so happens that automotive valves often have valve stems that are 5/16 inch in diameter.

If you've got some money and want to play around trying to improve the condition of the chambers you might go to your local Auto Supply and buy a Valve Stem Hone.

They don't require holding the cylinder too tightly and they can be used with a electric drill.

If you go this route, do not try to enlarge the chamber all the way to the bottom. Just concentrate on the first 1/2 inch of the holes depth.
The hone is designed for a thru hole so the bottom of the chamber may damage it.

Here's a link to show you what they are: http://www.goodson.com/240_Grit_Standard_Duty_Flex-Hones_in_14_Stock_Diameters/

 

[Artificer]

Well, I began working UnCivil War firearms in 1974 at the Spring and Fall National Championships of the NSSA at Winchester, VA. I worked at what was called “The Navy Arms Booth” for many years before Navy Arms set up their own “Official” booth a little way down Sutler’s Row from the Booth I worked at. The last year I worked there was around 2004. Over the years the booth sold brand new guns from Navy Arms, Euro Arms and in the last few years, some of the then newer Armi Sport guns.

When I began working there, we worked on many of the guns that had been imported from the 60’s and even some M 1851’s from the 50’s. Now, we did not handle FIE revolvers, so I can not comment on them. However, had any revolver we sold had incorrectly machined or undersize chambers, it would have instantly been replaced, corrected or the person’s money was refunded ”“ whatever the customer wanted. Further, I don’t remember it being a common thing that Revolver chambers were incorrectly machined or undersize, either. Perhaps it was true with FIE revolvers and some of the really poorer quality imports, but again, we didn’t handle them, so I can not say one way or another.
Gus

 

[Artificer]

Excellent post, Zonie.

I did not recommend a piloted reamer where the pilot would go through the threaded hole for the nipple because I have seen WAY too many of those holes that were off center to the chamber. Besides, it would be a bit too easy to mess up the screw threads.

A reamer with a short pilot that is not intended to go through the nipple hole would work, but then one would have to make a second reamer without the pilot to get to the rear of the chamber hole. THEN the front edge of that second reamer would have to be matched to the actual shape of rear of the chamber hole and is somewhat rounded as Flehto mentioned. However, one would really need to do a chamber cast to find out how the rear of the chamber hole is shaped, or you can not make the reamer fit the end of the hole in the chamber and are going to wind up with a shoulder in the chamber that will be difficult to clean and cause pitting problems later on. Now if one has a lathe and other equipment, these things can be done, but they are not things the average shooter can do.

Very much agree for someone who does not have machine tools and experience, if a flex hone can be found that fits, that probably is the least expensive and easiest thing for a person to do. (We used Flex Hones to polish the bores on the $ 12,000.00 to $16,000.00 Krieghoff Skeet Shotguns we had in the Corps and I have also used one to polish out a Brown Bess Repro Musket Barrel.) Here is a video talking about using them: http://www.youtube.com/watch?v=dW1fkiATS7M

I made a pair of Bronze rods (in both .36 and .44 caliber) that closely fit cylinder holes for holding the cylinder without damage to get rusted in/stuck nipples out of cylinders. There can be some surprising torque necessary to get old/hammered in/rusted in nipples out of cylinders when people don't remove them to clean them enough or even occasionally the way some Guerilla tightened them at the factory. The vise held the rods and not the cylinder.

For only one cylinder and when using a flex hone, two hard wood dowels that closely match the cylinder holes might work when one places the rear end of the cylinder on a soft mat and have the rods come in from the top under some weight or pressure. With short enough rods and some weight or pressure on them, you could still get at one open cylinder. Also, a strap wrench would probably be a good idea to hold the outer diameter of the cylinder (with at least two rods in the cylinder holes) so as not to damage the cylinder. We use strap wrenches to put on and more importantly take off one piece round free floating hand guard tubes on AR 15 type rifles and they will hold cylinders without damaging them to a surprising amount of torque - well more than needed to hold the cylinder to use a flex hone.

Gus

 

[Vaino]

Rounding off the cutting adge of a drill is standard practice in toolrooms when a non-standard reamed hole is wanted. The modified drill point behaves exactly like a reamer....it will follow the existing hole.

A lap could be used if not too much mat'l has to be removed, but there's always the possibility of "bellmouthing" the hole if withdrawn too many times.


If a reamer or modified reamer/drill is used, a slow speed, slow feed and plenty of cutting ooil ensures a smooth hole. If a still smoother hole is wanted, a few strokes w/ a lap w/ fine compound can be used.......Fred

 

[LRB]

I have seen a number of under sized chambers, even on NA guns. If you were not mikeing them, how would you know they were not too small. Most customers assume they are made right, and when they don't shoot accurately, just blame themselves or just don't know what the problem may be and think that's the way they all must shoot. I've had direct experience with two Ruger modern sixguns with under sized chambers, both in .45 LC.

 

[Artificer]

No, we did not use precision dial calipers or precision expanding or hole gages to check every cylinder on every revolver we sold, though we always had them and other precision measuring instruments with us at the NSSA National Matches to do so. Also, most NSSA shooters who attended the Spring and Fall National Championships did not bring precision gages to check them out, though many did. It was not unusual for shooters to have buddies who were machinists or on the NSSA Ordnance Committee bring such instruments to check the brand new revolvers when they were helping others to pick out a revolver or other gun at our booth, because we allowed and even encouraged it.

Further, if a revolver did not shoot well, it was common knowledge to check things like cylinder holes amoung other things, by NSSA shooters.

I certainly won’t disagree that a small percentage of Navy Arms or Euro Arms revolvers had problems that could include undersize cylinder holes, but it was FAR from a common or usual problem. Had it been, NSSA shooters of that caliber would have reported it or heard of it and we certainly would have heard of it at our booth in all the years we were there.
Gus

 

[Vaino]

Is it true that only one cylinder chamber is used if one wants to achieve maximum accuracy in a C&B revolver?

A few years ago I was shooting one of my MLers at the gun club and this guy comes over and wants me to shoot his C&B...complained that he wasn't satisfied w/ the accuracy.....some "fliers".

He handed me the loaded gun and I took 3 off handshots at 25 yds and had a 4" group and was about to hand it back to him when he asked if I would shoot 3 more rounds. The next shot was a "flier", the next one was in amongst the previous group and the last was another "flier.

Repeated shooting 6 rounds and the same thing happened. Didn't mark the 2 errant cylinders, but told him he should do it. Don't think it was the cylinder dias., but do think it was cylinder orientation. Could be wrong and it was the cylinder dias. Comments?. Not up on C&B revolvers.....Fred