A wood strip of the same type is used on one side of the finish or fine boring reamer 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 edge of this side opposite to that on which the wood strip is placed.
The choke boring reamer is used in shotgun barrels to cut the choke. After the finish or fine boring
reamer is used the choke boring reamer which has a tapered Lead an inch long which tapers about
.050" in this distance is used to bore out the choke portion of the barrel which is not bored out by the
finish boring reamer. A wood packing strip is used, with paper shims on the tapered portion of this
choke boring reamer and this reamer cuts on two edges.
The shotgun boring reamers are run at a low speed and plenty of cutting oil is supplied by a
low-pressure pump. In making the reamers they are hand honed after being ground to shape by a
surface grinder. They must be carefully checked for straightness. In doing the grinding, if much stock is
to be removed, do not grind a lot off of one side and then off the opposite side but take a small amount
off of the first side, then a like amount from the opposite side, then take the same from an adjacent side
and the same from the last side and repeat this until the reamer is ground to size, as this method of
grinding will prevent warping the reamer.
Choke boring is similar to quick-boring, except the cutting end of the rod does not go quite through the
barrel, being withdrawn and again inserted with a slip of paper placed between the slip of wood and the
cutter. This is worked not quite so far as the previous boring, being withdraws and another slip of paper
placed between the wood and the chatter, and this is worked in as far as desired. Care must be taken
that the choke be gradual and even. A finish can be given by folding a piece of fine emery cloth or emery
paper around a rod, and by turning this in the barrel, equalize any unevenness that may occur.
To enlarge the interior of a barrel, boring it choked at both breech and muzzle, push the rod to the
distance from the breech the enlarging is to start, and then start boring, leaving off where the muzzle
choke is to start. If the bore of a barrel is to taper from muzzle to breech, it will scatter. If made to taper
too much from breach to muzzle, it will compress the shot, and cause a very scattered pattern.
A very slight variation in the size of the bore of a gun-barrel at one of its ends often has a marked effect
on its shooting. If the shotgun tends to scatter the shot too much, it can usually be corrected by enlarging
the bore at the breech. Choke boring is another is another type of finishing the choke.
You will have to, or more than likely need to polish the choke area. This consists in dressing out the
breech with fine emery paper or cloth, wrapped upon a round wooden rod. A little oil should be used in
finishing the dressing, which will not extend above half the length from the breech to the muzzle.
No attention is needed to the slope of the choke, as the size of the bore, during this operation, is usually
largest at the breech. To do this get a break cylinder hone will work very good with the finest grit stones
you can get. It is usually necessary to hone the slope of the choke area, as the reamer will usually not do
that well there. This is where the old style square shotgun reamers work well as they will do a better
finish job there. You will need to braze a 1/4-inch rod to the hone so it can reach down the barrel to the
choke area. Then finish with a fine lapping compound. With the hone you will be able to do quite a bit of
alterations on the choke area. Be careful that you do not change the shape of the cone area as this will