Workbook

Now it is time to thread the barrel. Lock barrel up in vise jaws. Leading with the tapered side of the

die (9/16 x 24 tpi LH or 14mm x 1.0 LH for metric or AK brakes, 9/16" x 24 tpi RH for Inch

Pattern), insure your die is perpendicular to the barrel. Ideally, you will have the barrel held

vertically in the jaws to assist in getting it perpendicular. A large handle on the die works better than

a wrench because it is easier to keep straight. Continue cutting using cutting fluid or oil. Your goal

is to keep the work cool and to keep chips clear. Go slowly, backing die out often to clear chips. Die

should never become too hot to hold in your hand and remember which direction your are threading

- right or left hand.

After the die is all the way up to the shoulder, unscrew and repeat, leading with the flat side. It

should cut the last few threads a bit more. Then lightly file and sand any burs from the edge of the

shoulder, careful to keep it squared. Then, by rotating the barrel 45 degrees against a sanding block,

(fine - 180 grit or less) Break the sharp 90 degree edge just to the point where it won't cut you.

You are now going to relieve the threading with the edge of a thin, 6" file, all the way around the

barrel at the shoulder. Cut only the thickness of the threads. You then use a triangle file to bevel the

thread 60 degrees out of this groove you have cut. You can do the same at the start of the threading.

When you are done, screw the die back on to chase any burs. Your metric brake will now screw on.

THREADING INCH PATTERN

The procedure for inch pattern barrels is the same as for metric barrels, however when you are done,

you must align the bayonet lug (if permitted) at 6 o'clock and make a pin prick to mark the spot.

Unscrew the flash hider. Now take your smallest cut-off wheel (a small one about ¼" diameter is

best) and Dremel tool and cut a small radius for the indexing washer. Test fit the flash hider with the

washer and when the three holes align, drive in the pin and stake the sides.

L1A1s come with a washer that fits inside the flash hider so when tightened on, the flash hider

indexes properly. The thickness of this washer controls the point of indexing. Although not

absolutely necessary, it eliminates the slight wobble you may experience without it, as would

judicious application of permanent thread-locking compound. Take a .308" drill rod and insure that

your hider is aligned. If not, drill it out so you don't shoot it off.

Type I receiver