How To Repair A Swelled Gun Barrel

How To Drill Out A Blank Gun Barrel

Barrel drilling tools. A is plan and detail views of oil tubing used on butt drills. B is program and cease view of butt drill while C is underside view of aforementioned.

into the tool mail slot in the remainder. This tongue is just thick enough to extend a brusk distance down in the tool post slot and the block is held down by two cap-screws passing downward through it and into a bar of steel in the wide groove at the bottom of the slot. This block is drilled and reamed, out beyond the tool mail service slot, on the exact center line of the lathe, clear through from side to side. This hole is a close fit around the drill bulldoze tube which has no vee-groove in it at this bespeak This cake is slotted with a saw-cut from the outer end back through this hole for the drive tube to a short distance back of the pigsty, the full width of the block. Out beyond the bulldoze tube hole two cap-screws, from top to bottom through the block, clamp the sawed outer end of the cake together, squeezing the tube tightly in its pigsty.

The speed the barrel turns during the drilling operation is high and the feed of the drill into the blank is wearisome, as y'all have merely one cutting edge on the drill. Oil is pumped under pressure level through the tube from the rear end where a connectedness for a flexible oil tube from the pump is sweated onto the tube. This oil passes through the oil hole in the drill, comes out beneath the point, and returns, carrying the chips with it in the vee-groove on elevation of the drill and drive tube. The drill is footing to drill a hole .010" to .012" smaller than the diameter the finished bore is to be fabricated. The blank is carefully centered in the barrel chucks and the hole is started with a heart drill and and so drilled for a distance with a twist drill to give the butt drill a true start.

After the barrel is drilled it must be reamed to size and for this performance iii reamers are used, a roughing reamer and two finishing reamers, the last really being a burnishing reamer. Reamers are made of highspeed steel and are made with six grooves, except the roughing reamer which may exist made with four or half-dozen grooves. These barrel reamers take a rather long front end airplane pilot, the front finish of which is turned down for a short distance then that the tube which draws the reamer through the barrel tin can be brazed to the reamer pilot. . The ends of the reamer flutes just behind the pilot are given a slight taper to bring the reamer bore at this point to just under the bore of the drilled pigsty in the barrel bare and so that the reamer will first to cut easily. The cutting portion or flutes of the butt reamers vary from 6" to vii" in length. A pigsty of small size is drilled lengthwise of the airplane pilot from the front end to a necked portion just alee of the flutes and so that oil may be pumped to the reamer through the pull tube. From the end of this hole in the necked portion of the reamers, three small holes spaced equidistant around the neck are drilled at right-angles to the axis of the reamer so that the oil comes out at the front of the flutes. These front pilots are fabricated to simply fit the drilled hole of the bare on the roughing reamer, to fit the rough-reamed hole on the finishing reamer and to fit the finish-reamed hole on the burnishing reamer. The roughing reamer removes .005" to .006" from the drilled hole in the blank, the finishing reamer removes .003" to .004" and the burnishing reamer finishes the diameter to size.

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Barrel reamers. A is roughing type reamer, four groove, all carried through rear pilot. B is finishing type reamer, half dozen groove, three grooves carried through rear pilot. C is burnishing reamer, six groove, three grooves carried through rear pilot.

The flutes of the roughing and finishing reamers are cut .010" alee of middle every bit are those of the roughing and finishing chambering reamers, while those on the burnishing reamer are cut on center and finished to shape as are those of the burnish-type chambering reamer. Barrel reamers practice not have clearance ground upon them every bit do the chambering reamers, their clearance is stoned upon them by mitt. Butt reamers with spiral flutes are more efficient than those with direct flutes as they have a shearing cut merely these spiral flutes are far more than difficult to stone than are straight flutes. Barrel reamers are sometimes made with rear pilots as well every bit front end pilots and in this case the flutes are milled out through the rear pilots and then that the chips can pass off the reamer and on downward the butt.

In using the barrel reamers, the reamers are held stationary and the barrel bare revolves at a low speed as the reamer is drawn through the barrel by the oil tube which is fastened to a movable railroad vehicle such every bit the lathe carriage in case a lathe is used. A floating connectedness at the end of the oil tube should be used, and then that the reamers are entirely guided by the bore of the blank. The stop of the oil tube may exist plugged for 2" and a simple universal articulation used, fastened to this plugged portion, or a floating drive of the type described on chambering reamers may be used. The flexible oil line from the pump is led into the side of the hollow portion of the oil tube alee of the plugged end through a screw connection similar a nipple. This connection must exist removed to laissez passer the oil tube through the barrel blank, equally the oil tube is brazed to the reamer, and then put in place and the oil line continued to it earlier starting the lathe.

Shotgun barrels are made from steel tubes and although they may therefore be reamed to size with a serial of barrel reamers, such equally those used on rifle barrels, they are ordinarily bored with a long, 4-sided, square bit of high-speed steel, basis to size on a surface grinder. These bits are 10" to 12" long and have a tapered lead at the front terminate, most long on the roughing reamer and an inch long on the finishing reamer or bit. The driving rod for these bits is brazed to the rear end of the bit, the opposite end from that which has the tapered lead, and the bits are pushed through the bore as the barrel tube revolves.

A wood packing strip, turned on one side to the contour of the barrel diameter, is placed against one side of this flake, its full length, and on the roughing bit the 2 edges of the side diametrically reverse the side upon which the packing strip is placed do the cutting. Strips of paper are placed between the wood strip and the slow chip to cause it to cut larger subsequently each trip through the barrel.

A wood strip of the same type is used on ane side of the finish or fine boring bit but the leading edge of the opposite side has a small radius stoned upon it so that it does no cutting, which is all done with the trailing border of this side opposite to that on which the wood strip is placed.

Shotgun boring bit, too sometimes used on rifle barrels. End view shows how wood packing strip and shims are used.

A third square bit, the asphyxiate dull fleck, is used in shotgun barrels. Afterwards the finish or fine boring chip is used this choke boring scrap which has a tapered lead an inch long which tapers about .050" in this distance is used to diameter out the choke portion of the butt which is not bored out by the finish boring bit, but only past the roughing fleck. A forest packing strip is used, with newspaper shims on the tapered portion of this choke boring chip and this bit cuts upon two edges as does the roughing bit. These shotgun tiresome bits are run at a depression speed and plenty of cutting oil is used. In making the $.25 they are manus honed afterward being footing to shape by a surface grinder. They must exist carefully checked for straightness. In doing the grind ing, if much stock is to be removed, practice not grind a lot off of 1 side and and so off the opposite side merely take a small corporeality off of the outset side, and so a similar amount from the opposite side, and so take the same from an adjacent side and the same from the terminal side and repeat this until the bit is ground to size, every bit this method of grinding volition prevent warping the scrap.

Drills for boring out old barrels for relining (the insertion of rifled tubes) may be made from standard, high-speed steel, three or iv-groove drills with the regular twist flutes as fabricated by all drill making firms. These manufacturers will grind a pilot on these drills, to social club, to fit the old bore of the barrels to be re-lined, or past using an electric tool post grinder y'all can grind your own pilot upon them. The cutting edges at the rear cease of the airplane pilot must be ground with relief, as were the cut edges at the end of the drill originally. These drills volition non drill holes in solid metal only are used to enlarge cored or previously-drilled holes. A carbon-steel shank of whatsoever length may be welded to the shank of these drills.

If you lot wish to brand your own drills for drilling out barrels for relining they may be fabricated of a curt section, \fifty/2" to two" long, of high-speed steel by turning a pilot upon the front end to fit the old bore in the butt and turning down a brusk section of the rear end to a smaller size then that an oil tube may exist brazed onto it. The trunk ordinarily has three straight grooves milled lengthwise of information technology with a fluting cutter. The front end end of the lands between these grooves are relieved or ground as are the lips of a twist drill. A small hole is drilled lengthwise of the body from the shank stop about halfway through the trunk and holes are drilled into this at the finish toward the point of the drill from each of the grooves so that oil pumped through the oil tube can be forced out into the flutes, washing the chips out of the butt ahead of the drill and keeping the cutting edges cool. The pilot is grooved with the milling cutter which cuts the flutes so that the chips have a gratis passage.

Subsequently the old butt is drilled out with one of these drills it is commonly reamed with a barrel reamer of the regular fluted t}'pe to straighten the pigsty perfectly and bring it to size to take the lining tube used.

Half dozen-groove barrel reamer, of the blazon ordinarily used in sets of three, in graduated sizes.

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