After the final laps are cast, withdraw the rod just enough to expo« the cutter slot; insert the cutter» coat laps and cutter liberally with oil (preferably lard oil), and push through the bore until the end of cutter partly projects from the opposite end of barrel. Now draw the rod carefully the full length of barrel. Note whether the cutter has "taken hold." If not, shim it up with thin paper until it does. The sloping bottom of the slot in head permits a release of pressure on cutter during return stroke, thus preventing wear to the teeth. When the cuter will just start cutting, count carefully the number
of strokes made with it to deepen the groove the required amount. And be sure that you use the same number of strokes in each of the other grooves.
But to get back to this first groove we are working on. You can tell from the feel of the rod when the cutter is jumping over deeply pitted or corroded spots. The moment you get a full smooth cut, remove the entire head very carefully, after marking on muzale of barrel the exact point at which the cutter came out. Inspect the groove you have been cutting, and if clean and smooth from one end to the other, stop working on it. If pits still show, and you think it will stand deepening a bit, replace the cutter carefully in the same groove, and continue a few more strokes. An extra thickness of the» shimming should be used whenever the cutter stops taking hold.
Now remove all the shims and in like manner start in on the next groove. From now on you cut the exact number of cuts in every groove, regardless of whether all are properly cleaned up or not. When all grooves have been cut, if pits still show, select the groove having the deepest ones, and make a sufficient number of cuts in it to remove them, then a like number of additional cuts in all other grooves.
I should have mentioned that the better plan, when changing the cutter from one groove to another, is to melt off the old lap and cast a new one each time. This is not always necessary, but many old rifles do not have the grooves spaced evenly, and the new lap is advisable to avoid running the cutter against the side and widening the groove. ^
Before you started cutting, you should have made a small sulphur cast of the bore at the muzzle, and measured the full groove diameter. Now make another cast and measure groove diameter after the cutting. The bore should now be enlarged a corresponding amount, more or less, so that the grooves may be about the same depth as they were originally.
A straight spiral reamer should be ground to about .0015 less than the final diameter required. This reamer should be six inches long if possible, and should be relieved for a distance of 1 1/2 inches to enter the bore smoothly. Wrap the reamer in soaking wet rags, and braze the shank firmly to a long steel rod almost the full diameter of the reamer. Attach a strong handle, and ream the bore carefully full length, using the soda water and lard oil cutting compound mentioned in Chapter 31. There is little space between reamer head and the large part of shank to receive the cuttings, so the reamer should be removed frequently and chips carefully brushed off. Use plenty oj cutting compound. Be sure the reamer is not oversize for any point in the barrel, and if it stops do nOt try ro force it. Remove it. and you may find a cutting or two jamming the cutting edge or clogging the grooves. Do not cut for more than an inch or so before removing the reamer and cleaning off the cuttings.
When you have reamed clear through the boie, waih out with boiling water and dry thoroughly. Cast a regular lap and lap the bore for as long as necessary to remove all cross marks from the lands, and give it a bright polish. Thus you have rebored and rifled a barrel without changing the original pitch or rifling, and very little special equipment has heen used on the job. Before the final polishing you should check up on the bore diameter and its suitability for the ball you purpose using. It may be necessary to eicher find a new mold, or to lap the bore a trifle larger.
The reason for cutting the grooves before reaming the bore is that the old grooves provide a certain means of guiding the cutter for the new cuts; while reaming rhe bore might eliminate the grooves, leaving you with no cutter guide, if the reaming were done first. This method is entirely practical in old style barrels having very narrow grooves; but I would question its practicability in a barrel with wide grooves and narrow lands. Undoubtedly the lands would be damaged by the reamer. It will not work in a rifle with "gain" twist.
• CLEANING OFF RUST. Having either cleaned, or re-cut the inside of barrel we next turn our attention to the outside. Often it will be encrusted with rust, and the original finish completely obliterated. If it is desired not ro rebrown the barrel, try liberal applications of Hoppe's No. 9 followed by careful scraping with a scraper made of soft or half-hard brass, with edge filed square like a cabinet scraper. A piece of printer's brass rule is fine. This may be followed with a brass wire brush, using plenty of No. 9, which
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