Reactivating Drill Rifles

The Springfield 1903A3 rifle was the World War II variant of the venerable Springfield 1903 rifle from World War I. To expedite production, it used many stamped parts instead of milled components. The most notable difference was replacement of the barrel-mounted leaf/ ladder sight with a receiver-mounted aperture sight. Over 900,000 rifles were manufactured from 1942-1944 by Remington (707,000+) and Smith- Corona (234,000+).

After World War II many of these rifles were deactivated and provided to high school Junior Reserve Officer Training Corps (JROTC) and other cadet organizations. When I was in high school I attended a military class run by the California Cadet Corps under the California National Guard. In fact, I was the commander of the unit my junior and senior years.

We used deactivated Springfield 1903A3 rifles for drill; the barrel was plugged, the bolt face was welded, and the striker was ground down, but everything else on the rifle was functional. Most of us cadets wanted to own one of these rifles, so ever since my high school days I’ve wanted to have a functioning Springfield 1903A3.

As popularity and money for high school military programs waned, many of these deactivated rifles were returned to the military and eventually found their way to the Civilian Marksmanship Program (The CMP. org). In the fall of 2011, the CMP held a "junk" auction with over 80 palletsized lots of Springfield drill rifles with most lots containing 100 rifles. An individual who purchased one of these lots sold me one of these rifles.

Because the rifle was deactivated, not demilitarized, it had to be transferred through a FFL dealer. A few minutes of paperwork plus a transfer fee put this piece of American military history in my hands. Initial Assessment I completely disassembled the rifle for inspection and to determine what work I needed to perform, and what parts I needed to replace. There was no front sight blade.

The rifles we had in high school had the front sight blade installed, but I remember numerous cadets, including myself, getting cut by them during drill exercises so that is probably why this rifle didn’t have one. It looked like the magazine cutoff had been welded, but someone had worked on it to make it function again. The rear sight base was peened and bent, probably from cadets dropping the rifle multiple times, but I was still able to adjust the sight for windage and elevation.

The firing pin hole was welded on the bolt face and the striker (firing pin) was cut off so just the collar was left. The chamber had been torched and a steel rod welded in place and the barrel was tack welded to the receiver. The ejector and ejector pin was missing, the safety would not rotate, the upper band was loose and its screw was stripped. Finally, the safety plunger was broken. To my surprise, I couldn’t rotate the safety, which made disassembling the bolt a bit challenging.

I discovered the shaft was broken off of the safety plunger. This shaft guides the plunger into the hole, but now that it was broken, the plunger was hitting the side of the plunger hole effectively blocking it so it couldn’t move down. I used a small screwdriver to align the plunger with the hole and pushed down so I could rotate and remove the safety. Since the plunger is longer than the space between the shaft and the lever, it was installed prior to installing the shaft onto the lever.

The handguard ring would not come off because of the tack weld on the bottom of the barrel. I took a safeedge #0 narrow pillar file (Brownells #191-400-760) and filed down the top of the weld until it was even with the rest of the receiver so I could slip the ring off of the barrel. This turned out to be a stainless steel weld and would not take Parkerizing, but this was not a problem since the weld was on the underside of the receiver and would be covered by the stock.

Many of these drill rifles had the magazine cutoff welded in the off position so the bolt couldn’t be removed but cadets could still cycle the bolt. For many of these rifles this weld had to be cut through to remove the magazine cutoff. Removing the welded magazine cutoff in my rifle was much easier than anticipated. Since it was functioning all I had to do was remove the magazine cutoff screw and spindle and remove the magazine cutoff from the receiver.

Although the magazine cutoff functioned correctly, because this part was so damaged from the welding I purchased anew one. The ugliest part of this rifle was the cratered receiver where the magazine cutoff was welded. I could have had this TIG welded and then reshaped it, but I decided to leave it and just re- Parkerize it. Leaving it as is I can brag about how I recovered a drill rifle and show where it was originally welded. However, I wanted the magazine cutoff to function correctly so I cleaned up the detents.

I took a 3/32" carbide ball end milling bit and my high-speed rotary tool set to the lowest speed and opened up the welded center detent. I reinstalled the old magazine cutoff and tested it

with the bolt and everything worked as it should. The center detent was in the proper position so the bolt could be removed and installed easily. I also cleaned up the On and Off detents with the 3/32" carbide ball end bit because they had some metal splash from the welding. Now the magazine cutoff plunger sets securely into each of the three detents. So what exactly does the magazine cutoff do?

In the down or Off position, it will not allow the bolt to come back far enough to feed rounds from the internal magazine, essentially making it a single-shot rifle. In the center position it allows the bolt to be removed and installed. In the up or On position, it allows the bolt to come back far enough so the rifle will feed rounds from the internal magazine. Also when in the On position, after the last empty case is extracted and When freed, it functioned but I replaced it for cosmetic purposes.

I didn’t polish out receiver weld. ejected the follower prevents the bolt from closing, thereby indicating that the magazine is empty. To clean up the rear sight base, I completely disassembled it and noticed that the sight base was heavily staked onto the receiver. I found on the Internet that this seems to be common with rifles manufactured by Remington so I decided just to leave it alone and treat it as part of the receiver.

I took a brass punch and pounded the sides of the rear sight base until they were straight. I took a file and cleaned up the burrs on the top of each side, then used a rubber polishing tip and my high speed rotary tool to polish out the file marks. The most difficult part of the recovery process was removing the welded barrel.

The proper method is to use a lathe to not only remove the barrel weld, but to remove enough of the barrel shoulder to reduce the interference fit of the barrel to receiver face to facilitate easy removal of the barrel. I don’t have a lathe so to remove the weld I used the same safe-edge #0 narrow pillar file I used previously. I started at the end of the weld and rested the safe edge of the file against the receiver face. I began filing the weld being careful not to cut into the receiver face.

After I filed off some of the weld to expose the barrel, I rotated the rifle so I could file off more of the weld, making sure the safe edge of the file was resting against some exposed receiver face to keep the file square and flat. Because the weld was so high I started filing on the other end of the weld being careful as before. I continued to file both sides of the weld until I had a bare-metal cut in place of the weld indicating that I had removed the weld metal and had started to cut into the barrel.

I filed a little deeper to make sure I had removed the entire weld. The barrel was now ready to be removed. I already had an action wrench from Brownells so all I needed was the Springfield 1903 Head (#080-801- 003). A properly fitting head is important because this prevents the receiver from warping or otherwise becoming damaged when removing the barrel. I also already had the barrel vise, but I didn’t have a bushing that fit the barrel, so I had to make one.

I marked the barrel just in front of the chamber swell, and made another mark 1 1/8" farther down the barrel. The barrel diameter measured at the two marks was 0.980" and 0.942", meaning the barrel had a 0.968-degree taper. I’ll discuss the math to calculate this taper below. I used Bob CAD-CAM v20 (bobcad.com) to create the CAM code, then used my MAXNC 10 CL hobby CNC mill (maxnc.net) to mill the bushing from 1 1/8" aluminum stock.

No matter how hard I tried I couldn’t remove the front sight base from the barrel, so I cut off the barrel about an inch behind the front sight base. This is a throw-away barrel

I was careful not to touch the receiver face. Notice the steel rod welded inside the chamber so cadets couldn’t chamber around. anyway and I ordered a replacement front sight base. I attached the receiver wrench to the front of the receiver using the Springfield 1903 head. I coated the inside and outside of the barrel bushing with rosin (Brownells #083-016-100), positioned it on the barrel, then installed and tightened the barrel vise onto the bushing.

I positioned the barrel vice in a wellsupported bench vise and used a two-foot length of pipe on the action wrench to gain some additional leverage. Thanks to this additional leverage the barrel easily came loose, even after almost 70 years. As my father taught me, it helps to have the right tools!

Replacement Parts I purchased the following parts from Numrich Gun Parts Corporation (GunPartsCorp.com, All the replacement parts, except the barrel, came stamped with an "R" indicating they were all manufactured by Remington; a perfect match for my rifle. They included anew Criterion barrel (1087210), safety lock assembly (514340B), striker (514510), magazine cutoff (515370), front sight base (524910), front sight key (524650), front sight blade (524900), bolt body (514520), ejector (515760), ejector pin (515750).

I not only wanted my rifle to function like new, I also wanted it to look like new so I decided to re-Parkerize the visible parts. Parkerizing is a very simple, inexpensive process that applies a more durable finish than bluing. This is why manufacturers starting Parkerizing military guns to keep up with the demands of two world wars. Parkerizing also covers up nicks, scratches, and other imperfections, and this rifle has almost 70 years of imperfections and cadet mishandling!

I have Parkerized a number of guns and each one came out beautifully. I purchased a jumbo combination (black and grey) Parkerizing kit from Home Parkerizing Kits (ParkerizingKits.com, and used the grey to match the original military Parkerizing on early ’03-A3s. Later rifles came with a grey/green Parkerizing. I took all the parts I wanted to re-Parkerize and first removed any unsightly burrs. The new bolt body I received was blued and packed in grease.

I removed the grease by soaking the bolt body in solvent, then bead-blasted the parts down to bare metal which gave them a nice, even, matte finish. I thoroughly cleaned and degreased all the parts, and prepared the grey Parkerizing solution according to the instructions. Using nylon cable ties to suspend the parts and provide a means to remove the part from the hot Parkerizing solution, I heated the solution in a large stainless steel cooking pot to 190-degrees Fahrenheit and immersed the parts.

After the parts stopped bubbling I removed them from the pot, thoroughly rinsed them with hot water, then coated them with the provided light oil. Some areas on the receiver and the bolt sleeve wouldn’t take the Parkerizing. I bead-blasted them again and then dipped them in an acid bath made of one part muriatic acid and four parts tap water for 30 seconds, then thoroughly rinsed them in tap water. This time the Parkerizing came out evenly.

After Parkerizing the parts, I polished the bolt locking lugs on the new bolt. This ensured that the bolt locking lugs mated evenly with equal pressure which can provide some increase in accuracy. This process can also changed headspace, which is why I performed it before I installed the new barrel. I installed a spring onto the steel rod that was welded into the chamber of the old barrel and screwed the old barrel onto the receiver so the spring applied tension on the closed bolt.

I removed the bolt, applied some 800-grit lapping compound onto the recoil lugs, opened the bolt about 45degrees, then closed the bolt. Opening and closing the bolt numerous times lapped the recoil lugs. The spring applied rearward pressure on the bolt to facilitate the lapping process. After 10-20 open/close cycles, I removed the bolt, cleaned the locking lugs with brake parts cleaner, and examined the progress.

I applied more lapping compound and continued the open/close lapping process until both lugs were evenly lapped, then removed the old barrel and cleaned both the receiver and bolt with brake parts cleaner. Barrel Work The barrel I ordered from Numrich had a few problems. There was no alignment mark on the side of the barrel as found on military barrels, so the only way to index the barrel properly was to install the front sight base and "eyeball" it.

I discovered the slot in the barrel for the sight base key was too wide. The front sight base would not fit tightly onto the barrel because the wide slot allowed the sight base to

I performed the same process to the bolt and other visible parts. The barrel was already Parkerized. The post welded in the chamber acted as a spring guide. rotate. I peened the edges of the slot until the key fit tightly, then silver soldered the key in place. Now the front sight base fits tightly onto the barrel and does not rotate. I screwed the new barrel onto the receiver until it was hand tight and discovered that the barrel was rotated about 75 degrees, making it way too tight.

The proper method for reducing the interference fit is to turn down the barrel shoulder on a lathe, which I don’t currently have. Another method for reducing the interference fit is to use 400-grit lapping compound and lap the barrel shoulder to the receiver. This method removes metal from both the receiver face and barrel shoulder, as well as squaring these two surfaces. By removing metal from the receiver face, anew barrel won’t be able to be installed on this receiver.

Not a problem because I don’t plan to ever put another barrel on this rifle. I screwed the new barrel onto the receiver until the barrel shoulder was about 1/8" away from the receiver. Using a toothpick, I put some 400-grit lapping compound into that space, then screwed the receiver down hand tight while being careful to not get any lapping compound onto the barrel threads. I set the barrel straight up in a vise and alternately loosened and tightened the receiver.

After about 20 or 30 cycles of loosening and tightening I cleaned off the lapping compound with brake parts cleaner and checked my progress. A grey ring was starting to form around the barrel shoulder and receiver face. I continued this process until the barrel was about 16-degress off to the right. This will provide the correct amount of interference fit (tightness) for the barrel and receiver.

There was also a solid grey ring around the barrel shoulder and receiver face indicating that the barrel was lapped and square to the receiver. I coated the barrel bushing with rosin as before and slid it onto the barrel. Then, I installed the barrel vise onto the bushing and the action wrench onto the receiver. I put the barrel vise into the well-supported bench vise and tightened the receiver until the front sight base was vertical and centered.

The new barrel came with a chamber that was cut 0.005" short so I had to finish reaming the chamber to the proper headspace. I measured the headspace of the new barrel—a very important procedure when replacing a barrel is to check the headspace— and used the new bolt body so just the bolt face came in contact with the gauge. When testing headspace, there should be no extractor or ejector tension on the gauge.

I inserted a .30-06 Go headspace gauge into the chamber and gently tried to close the bolt body using just light finger pressure. Never try to force a bolt closed on a gauge; light finger pressure is all that is needed. I used the Go gauge because this was anew barrel with a short chamber. At the point where I just started to feel some friction, the bolt would not close completely. This indicated that the chamber was too short.

I rented a .30-06 chamber reamer from Elk Ridge Reamer Rentals (ReamerRentals.com, and put the pull-through rod through the chamber and out the bore until the reamer was visible in the receiver. I liberally lubricated it with cutting oil and pulled the rod until I felt the reamer contact the chamber. With about ten turns clockwise as viewed from the muzzle (never counterclockwise as this could break the cutting teeth) I could feel the reamer cutting into the new barrel as it cut a longer chamber and new throat.

Pushing the reamer back into the action, I could see the flutes had steel dust from the reaming process. I removed the reamer and rod by pulling them back through the action, thoroughly flushed the reamer and chamber with brake parts cleaner to remove all chips and cutting oil, then ran a clean dry patch through the bore from the chamber to the muzzle. It still wouldn’t close on the Go headspace gauge, so I had to do more cutting.

I repeated the cut ten more turns, cleaned and measured process until the bolt finally completely closed with the Go gauge in place. The chamber and throat were now cut to the proper length. I also measured headspace with a .30-06 Field gauge just to make sure the chamber was within specification and the bolt would not close. Reassembly After I finished reaming the chamber I completely reassembled the rifle with the replacement parts.

Everything went together as it should and the re-Parkerized parts made the rifle look almost factory new. The front sight base key didn’t have a notch so I drilled a notch so the pin would fit. I made sure all moving parts were either oiled or greased before assembly.

The lap is spun at 500-700 RPM and rotated so the lap maintains the same angle in relation to the muzzle. The upper band was very loose and it looked like someone tried to tighten it by over-tightening the upper band screw, causing it to strip. The upper band hole in the stock was too large, causing a large amount of slop and play in the upper band. This may have been done on purpose to prevent cadets from installing a bayonet. I drilled out the hole in the stock to 1/4".

I glued apiece of 1/4" hardwood dowel into the hole and sanded it flush with the stock, then drilled a hole through the dowel using a #26 drill bit. Now the upper band has no slop or movement. I discovered that the extractor wouldn’t slip over the rim of a singlefed cartridge but it worked perfectly when feeding rounds from the magazine. I put a rubber polishing tip on my high-speed rotary tool and polished the face of the extractor. Originally it had a sharp edge transitioning to the bevel.

I polished that edge and the bevel, then cold blued the entire extractor. Now the extractor slips easily over a single-fed cartridge. When anew chamber is cut in a barrel, the reaming process leaves small burrs perpendicular to the bore. These burrs can tear copper from the bullets which turn into plasma and are deposited in the bore as copper fouling. Barrel break in removes these burrs and polishes the bore, helping to prevent fouling.

Normal barrel break in consists of five cycles of shoot one round then clean the barrel, followed by five cycles of shoot two rounds with a barrel cleaning, followed by five cycles of shoot five rounds then clean the barrel, follow by five cycles of shoot 10 rounds and clean the barrel. Each cleaning should be performed with copper solvent to remove all traces of copper fouling. My barrel break in is a combination of hand and fire lapping to polish the chamber throat and lap the bore.

I performed this procedure with anew M1 Garand barrel and it worked very well. So well that after a range session firing 10 eight-round clips the barrel had no copper fouling and needed only three patches to come clean. The purpose of this procedure is to polish out any burrs left in the barrel throat from the reamer, and to polish and gradually taper the barrel for increased accuracy and ease of cleaning.

Traditional fire lapping drives bullets impregnated with lapping compound through the bore at very low velocities. Cases used for fire lapping have to be discarded as the case neck becomes contaminated with the lapping media. Although this method does wonders for the bore, it also lengthens the barrel throat, reducing barrel life. My method polishes the throat without increasing its length, laps the bore and I don’t have to throw away the cases!

Start by loading 15 rounds of .30- 06 with 5.0 grains of Red Dot behind a 150 grain FMJ boat tail .308 bullet and a large rifle magnum primer. I use magnum primers because there is so little powder in the case. Anything less than 5.0 grains of powder will cause the bullet to get stuck in the bore.

With a bore guide in the action to prevent the lap from depositing compound in the chamber, I wrapped a .45 caliber cleaning patch around a .25 caliber bore brush with the patch impregnated with USP Bore Paste (USPBorePaste.com, I ran the tight-fitting patch back and forth through the entire length of the bore 20 times, being careful not to allow the lap to come all the way out of the muzzle or all the way into the chamber.

This performed the hand lapping part of the process and left a small amount of compound in the bore. I fired one low-velocity round through the barrel for fire lapping. Afterward, I inserted the bore guide into the action and ran an USP-impregnated tight patch back and forth 20 more times. This cleaned any powder residue and fouling from the bore and prepared it for a second low-velocity lapping shot.

After performing this lap/shoot process for five shots, I thoroughly cleaned the barrel using patches with solvent followed by dry patches. This removed any residual lapping compound in preparation for the next finer compound. Using a clean patch with J-B Bore Bright (Brownells #083-065-100) instead of USP, I performed the lap/ shoot process sequence for another five times as before, then thoroughly cleaned the bore again with solvent and patches.

Finally, I performed the same hand lap/fire lap process an additional five times using Iosso Bore Cleaner (iosso.com, which has the finest grit. This process performed the final polish of the chamber throat and bore. The bore was mirror bright and smooth and now ready for full pressure loads with a polished throat that will prevent excessive fouling. The last thing I did just to make sure I hadn’t picked up any nicks or burrs on the muzzle crown was to lap the muzzle.

This removes those nicks and burrs and makes the ends of the lands and grooves sharp, and can enhance accuracy. I put some 400-grit lapping compound on the end of a brass muzzle lap attached to a variable

Threaded brass pins will prevent the crack from spreading. I cut the pin and file it flush with the wood. speed drill. With the drill running at about 500-700 RPM, I touched the ball end of the lap to the muzzle held at an angle and rotated the drill through 360 degrees, keeping the lap at the same angle. I did this for about a minute, making sure I kept rotating my drill in a circular motion. I cleaned the excess lapping compound off the muzzle and ran a cleaning patch through the bore from breach to muzzle.

The muzzle had a bright ring around the inside and the lands and grooves were nice and sharp. I installed the new blade in the front sight base and used a 1/16" roll pin because I didn’t have a solid pin to mount the blade. The pin was nice and tight so the blade didn’t move. Stock Work I decided to refinish the original stock and handguard rather than purchase new ones. I’ve refinished a number of gun stocks and they come out looking almost like new, although this one was pretty beat up.

With the rifle completely disassembled, I removed all the metal parts from the stock and handguard. I used Klean-Strip KS-3 Premium Stripper, a semi-paste that adheres to the wood. I applied the stripper with a brush, allowed it to set for 15 minutes according to the instructions, then wiped it off with a paper towel. The first application removed almost all of the old finish. I applied a second coat of stripper and used a stiff nylon brush to work it into all the crevices, wiping off again after 15 minutes.

After the third application I soaked a green scrubbing pad in mineral spirits and rubbed down the wood to remove all excess stripper and completely clean the wood. After the wood was stripped and cleaned it appeared like someone had tried to refinish this stock once before and did a poor job of sanding. However, many of the original cartouches became visible after I stripped away the old finish. After the wood dried, I applied a wet cloth and pressed a hot iron to it. This process steamed out dents from the wood.

If this was a collectable stock I would not apply steam to any cartouches as this could remove them. I steamed the entire surface of both the stock and hand guard three times to make sure I raised as many dents as I could, then set them aside to dry. After the wood completely dried, I lightly sanded with 400-grit paper, then applied Minwax Gunstock #231. I wiped off the excess with a clean cloth and allowed the wood to dry overnight.

Then, I applied a coat of Minwax Clear Satin Fast-Drying Polyurethane to all the inside areas of the stock and handguard. This will prevent moisture from getting into the stock, especially the parts touching the metal receiver or barrel and causing rusting and pitting. Once the stain was dry I applied three coats of Birchwood Casey Tru-Oil. Tru-Oil provides a durable, easy-to-repair finish that I use on all my gunstocks.

I allowed each coat to dry for six hours, burnishing the surface with a nylon stocking after each coat. I don’t usually use steel wool because it can leave steel filaments behind in the wood. The stock was cracked from the magazine cutoff detent back to the wrist; but it was only cracked on one side. I couldn’t open the crack far enough to put in any glue so I decided just to use pins. I took a 3/32" brass rod and threaded it with a 4-32 die.

I threaded enough so I could cut two pins, used a #44 drill bit and drilled a pilot hole in the stock. I made sure I didn’t go through the bottom of the stock and applied a clamp to the stock to keep the crack as tightly closed as possible. I cut apiece of the threaded rod long enough so I could insert it into the chuck of my variable speed drill. Applying some epoxy to the threads of the pin, I used the variable speed drill at a very low speed to screw the pin into the hole.

I carefully cut and filed the pin flush with the wood, then touched up the wood with sandpaper, stain, and finish to match the rest of the gun. After the glue dried on the first pin I performed the same process to a second hole drilled from the bottom of the stock. This fix should prevent the crack from spreading any further. Result I was very pleased with the result of all my work. The stock was in pretty bad shape to begin with but now has a very nice finish. Everyone keeps telling me it has character.

All the external metal has been refinished and everything functions as it should. You can still see a small spot of stainless steel where the old barrel was tackwelded to the receiver, but this is covered by the stock and does not show. I left the receiver weld alone where the original magazine cutoff was welded. Because of the different consistency and hardening, the weld

This picture just doesn’t do it justice. metal Parkerized differently than the rest of the receiver. So how does it shoot? With a brand new, lapped barrel and proper bench rest technique, this rifle is very accurate. And, because I lapped the barrel, it took only three patches to clean it after firing 40 rounds through it. I am now the proud owner of apiece of U. S. military history that I restored to shooting condition.

So why go through all the trouble and expense of converting this drill rifle into a shooter when I probably could have purchased a shooter for about the same price from a gun show? First of all was the challenge of the project and doing the work. Part of the pleasure was doing the work myself and seeing the result. Second, my rifle now has a brand new barrel and refinished parts.

Even if you could find anew, never-fired ‘03-A3 it would cost upwards of $1,500+ whereas I spent far less than half that for parts and tools, including the price of the drill It shoots as good as it looks. rifle. A gun show rifle wouldn’t have a new barrel or new finish. Best of all, I now have a functioning Springfield 1903A3 for my collection that will last for thousands of rounds.

I know I probably won’t come close to putting a thousand rounds through this rifle but I do enjoy seeing those longing looks from fellow shooters when I take it to the range. So the next time I participate in a bolt-action military rifle side match, guess which rifle I’ll be taking along! Calculating Barrel Taper Gunsmithing requires some math capability; especially when it comes to measurement and dimensions. I needed to calculate barrel taper so I could make a tightly-fitting aluminum bushing for my barrel vise.

My bushing had to be 1 1/8" long to fit in the barrel vise, so I made two marks on the barrel just below the chamber swell that were 1 1/8" apart. The barrel diameter at the two marks was 0.980" and 0.942" so I made a drawing to represent the dimensions. I moved both vertical lines up until the bottom of the small vertical line was at the end of the horizontal line. This helped me to visualize what I needed to do. Now I needed to know the length of the small vertical section on the left.

To find this, I found the difference between large and small vertical lines (0.980" – 0.942" = 0.038"), then took half that because the small line is in the center of the large line (0.038" / 2 = 0.019"). So the small line was 0.019". I drew a line from the bottom of the large vertical line to the bottom of the small vertical line and now I had a right triangle to calculate the angle. Trigonometry… I can hear some readers groaning from here! First I needed to find the length of the hypotenuse.

Remembering Pythagoras, with a right triangle A^2 + B^2 = C^2. So now I had 0.019^2 + 1.125^2 and taking the square root of that sum is 1.1251604330050004 029069759316584" So now I needed to find the angle A indicated by the arc in the diagram. As a reminder, SOH (Sine equals Opposite over Hypotenuse), CAH (Cosine equals Adjacent over Hypotenuse), and TOA (Tangent equals Opposite over Adjacent) helps to remember the relationships of the angles and sides of a right triangle.

The side opposite from angle A is 1.125" so I used the Sine function to find the angle. Sine(A) = 1.125" / 1.125160433005000402906975931 6584", so solving for A yields A = arcsine(1.125" / 1.125160433005000 4029069759316584"). Note, on a scientific calculator (or calculator program on your computer or smartphone) arcsine, the inverse sine function, is likely under the INV check box. So the angle worked out to be 89.032 degrees.

This was very close to 90 degrees which I knew was right, but would have been much too large to make my bushing. The two non-right angles of a right triangle equal 90 degrees so I subtracted 89.032 from 90 for a difference of 0.968 degrees. This was the angle I used to make the bushing. My high school math teachers would be so proud! AG Angle A was the angle I need to find for the barrel bushing.