Brownells Brownells Brownells 75th Anniversary - A Shooting Heritage

Building a 1911 Style Race Gun

By Mike Watkins

IPSC competition is a fun and challenging part of the shooting sports to be involved in and there are several different class levels you can compete in. For instance, are you competing in IPSC stock gun class now and wanting to move up to Open Class? Or do want to jump right into Open Class with a Race Gun?

You can start a couple of different ways; Purchase a complete Pistol from one of the excellent Pistolsmiths or companies out there. Or build your own; this article will cover how to assemble a .38 Super High Capacity Race Gun.

If you don’t have access to a Milling Machine and Lathe for the required machine work necessary you want to start with something like the STI 2011 Short Block Kit (#791-000-001). It has the machine work done and the fitting of the slide, frame, and barrel. All you have to do is fit the fire control parts and other small parts. Add a Red Dot mount, your favorite Red Dot Sight, and the final finish. A simple, and fun way of getting started and adding a very nice pistol to your collection.

For this article, we’re going to start with separate components and do all the machine work and fitting ourselves. I had a Caspian Hi-Cap Frame (#168-000-008), Caspian slide in .38 Super (#168-000-050), and a Schuemann Hybrid barrel (#836-011-160), EGW Hybrid style Comp (#296-114-101) in my shop all ready, so let’s use them.

The Caspian frame comes with a grip safety, mainspring housing, magazine catch, and ambidextrous safety of there own design, so we don’t have to choose what to use there. As I fit each major component I completely deburr and smooth all surfaces at the same time, so I won’t repeat that as we go thru building the Race Gun.

There will be a tool and parts list at the end of this article for you to refer to.

Fitting the Slide to Frame

To get started, I like to make a rough drawing of the slide and frame with dimensions of each written down so I know where metal needs to be removed to fit them together. Then I square the frame in the mill and machine the outside of the frame rails the required amount for it to fit the slide. You will need to use a frame rail file to file out the inside of the rails on the slide and frame for them to fit together. If I need to remove material from the top of the frame rails or the bottom of the slide, I use a 6 inch mill smooth file and draw file them by hand.

You’ll want to fit them so the slide will go onto the frame tightly without binding, remember to oil them so they won’t gall and stick together. I quit filing when I can install the slide almost all the way onto the frame. Then we can do the final fit by lapping them together.

I start with 600 grit Aluminum Oxide Lapping compound and work the slide back and forth on the frame with a slide lapping tool that connects to the slide like a bushing with a handle on it. As soon as the slide will go all the way back on the frame. You will want to stop and clean off the 600 grit lapping compound. Then coat the slide and frame rails with the 800 grit lapping compound and slowly finish lapping them until the slide will move smoothly without binding on the frame. Then Stop, you are trying for .001 clearance between them, with no binding. Now that the slide and frame are fitted we are ready to machine the slide for the Schuemann HybriComp barrel.

Installing the Schuemann HybriComp Barrel

The machine work required for a HybriComp barrel is different from a standard barrel because you will have to machine a slot into the top of the slide for the rib on top of the barrel. Be sure you read and understand the instructions that come with the barrel completely before you start.

Cutting the slot for the rib will require that you measure the distance from the front of the slide to the back surface of the slide locking lug. Then, measure the distance from the back of the barrel rib to the back edge of the back locking groove. Subtract the second measurement from the first. Measure this distance back from the front of the slide and scribe a mark on the top of the slide to indicate where to stop your mill cut at. Clamp the slide in your mill vice and level it. Find the exact center of the slide and make a 7/16 inch mill cut from the front of the slide back to your scribe mark. Make sure you have .010 to .020 clearance on the barrel rib so that it does not bind on the slide during cycling of the slide. The back lower rear corner of the slot, on the inside of the slide will need to be chamfered to clear the radius of the fillet on the back of the barrel rib. I use a die grinder with a ¼ inch round carbide cutter to do this. The rest of the barrel fitting is the same for a ramped barrel.

You will have to fit the barrel hood so the barrel will go all the way into the slide. I measure the width of the barrel hood, which is oversize by about .010 of an inch usually, and write down that dimension. Then with your dial caliper measure the width of the slide breech face, write that down and subtract the two. This will show how much needs to be removed from the hood for it to fit into the slide. About .001 of an inch clearance on each side of the hood is what you are striving for. Carefully file each side of the barrel hood, while trial fitting it into the slide. Use a barrel alignment block to hold the lower lugs or feet square and centered in the slide when checking the hood fit in the slide. You want to be sure the hood is filed evenly on each side to keep it centered in the slide. Once the hood will slide into the breech face area, you will now have to shorten the length of the hood so the barrel will go all the way back into the slide, to allow it to go up into lockup into the slide lugs. EGW makes a hood length gauge to measure the slide with, and you can transfer that measurement onto the barrel hood to see how much metal to remove. I modified my dial caliper arm on one side with a relieve cut so that it would clear the lip or overhang on the slide ejection port and reach the back surface of the rear lug. Then I can measure directly from the rear lug vertical surface to the breech face, and scribe that distance on the top of the barrel as a stop line. You can file the back of the barrel hood or machine it off in your mill to the correct length.

With the hood now fit into the breech of the slide, you can measure the barrel lockup into the slide upper lugs. Install the barrel into the slide and with the barrel hood forward of the breech face, hold pressure on the barrel upwards into the top of the slide. With your caliper measure from the top of the slide down to the top of the barrel, write it down. Then slide the barrel back against the breech face and the barrel up into the slide upper lugs into full lockup, measure this distance. The difference between the two is the amount of barrel lockup and should be .045 inch or more. If not you may have to file the barrel upper lugs to achieve that measurement and full lockup. Be sure to watch that the barrel sides are not contacting the inside of the slide, and not allowing the barrel to go fully up into lockup.

Now we have to machine the frame for the ramped barrel, in this case it has a Nowlin/Wilson ramped barrel. I will also include the cuts needed for a Clark/Para ramped barrel.

Clamp the frame in the mill vise with the rails horizontal and level; touch a 3/8 inch four flute flat bottom center cutting end mill to the top of the rails lightly to zero the mill cutter. Then center the end mill between the frame rails and lower it down .315 inches and cut a slot for the barrel feet ramp into the magazine well from the barrel lug slot in the frame. With a Nowlin/Wilson ramp barrel, insert a slide stop into the frame and measure from the slide stop pin back to the vertical face of the barrel lug slot in the frame.

Subtract this distance from .500 inch and write it down. Clamp the frame with the rails vertical in the mill vice, and with a Nowlin ramped barrel frame bridge cutter, move the vertical face of the lug slot back the distance you measured above, usually around .160 inches. Now you can clamp the frame in the mill vise at a 45 degree angle from vertical. Chamfer the corner of the two above cuts its full length between the frame rails and so that the chamfer has a width of .050 of an inch. Use a flat needle file and round the sharp two edges of the chamfer to match the rounded mating corner on the barrel, about a 1/16 inch radius.

If you are using a Clark/Para ramped barrel the .315 slot cut is the same. But the second cut is different; insert a slide stop into the frame and measure from the back of the pin to the vertical surface of the lug slot. Subtract this distance from .600 of an inch, write it down. With the frame in the mill vice, with the rails horizontal, lower the end mill down into the frame. Move the vertical surface back the results of your measurements from above, usually about .260 of an inch. Now use a Dremel tool or a round needle file to radius the sharp edge of those two cuts to about 1/16 of an inch to match the fillet on the back of the barrel lugs. As you can see the Clark/Para ramp cut is easier as you can level the frame in the mill vice and make both cuts without having to reposition the frame. With that machine work done we can assemble the barrel into the slide and onto the frame so that we can check the fit of the frame cut to the barrel lugs, to be sure nothing is binding. Everything fits perfectly, right.

Take the slide off of the frame and align the barrel square to the slide with a barrel alignment block and install a Brownells barrel holder. Tighten up the setscrew to hold the barrel fully upward into lockup. Remove the barrel alignment block and install the slide onto the frame. Using the Brownells Lug Cutter installed on the frame, proceed to cut the barrel feet. I use the small .186 cutter and hand fit the rest, so I can file out any machine marks and polish the engagement surfaces. Install a thumb safety into the frame also; as I cut the feet just to the point that I can raise the safety up into its notch in the slide. I like using hand pressure on the back of the slide to push the barrel feet into the lug cutter so it takes a smoother cut. Be sure to clean the chips out of the cutter often and check your progress as you go. Never turn the cutter backwards or you will break the teeth off of it.

Normally you will cut only until the cutter reaches the back surface of the barrel feet and the safety will go up into the slide notch with about 1/16 of an inch clearance on the face of the safety to the notch. Don’t worry if the slide is not flush with the back of the frame, these will be blended in later. If you do cut until they line up flush, you have probably cut the barrel feet too far. You will want to check the disconnector slot in the bottom of the slide to make sure it lines up properly to the disconnector hole in the frame.

The final fitting of the lugs will be by hand using a 3/16” inch round smooth file. You will want them to lock up tightly on the slide stop pin, without binding or taking to much effort to lock and unlock them. The lugs should touch on the back and bottom of the barrel feet against the slide stop pin.

Now measure the distance from the barrel link pin hole to the lugs where they rest on the pin and choose a link with the same length as measured. I paint the sides of the barrel feet with a black marker and hold the link on both sides of the lugs with a link pin installed about halfway. You can then rotate the link thru its arc of travel and scribe a line on the sides of the lugs as a guide on how much metal to remove from the barrel feet surface. You can now install the link into the barrel with the link pin. Holding the barrel upside down, install the slide stop pin thru the bottom link hole. With the slide stop all the way to the rear of the barrel feet, the link should rotate freely forward at least 45 degrees with the slide stop pin clearing the barrel feet with no binding at all. This is for link movement to clear the barrel during cycling, with the slide stop in place, and to prevent the lugs from bumping into the slide stop pin. The flat where the barrel feet rest on the slide stop pin should be as long as possible for best accuracy and to delay barrel unlocking. Assemble the slide, barrel, and slide stop onto the frame. The barrel/slide should go completely forward into battery to full lockup without binding. Now check if the barrel/ slide will go all the way back, linking down the barrel, its full rearward travel. If it does not, the rear of the barrel feet ramp is contacting the frame vertical surface to soon preventing the barrels top locking lugs from clearing the slides locking lugs. You will have to move back the vertical surface in the frame .005 of an inch and the radius corner back .005 of an inch. Reassemble the slide/barrel on the frame and retest. If it still does not unlock the barrel and move all the way back, continue removing .005 of an inch at a time and retesting until it does. With a HybriComp barrel there must be at least .010 of an inch clearance between the top of the barrel and the inside of the slide. You may have to remove more material from the vertical surface in the frame, as above, to get that clearance. Never remove more than another .010 of an inch, without checking what else may be preventing the barrel from moving all the way down.

To help see where the barrel may be binding, use a black felt tip marker to paint the surfaces where contact might be possible, and move the slide back and forth as much as you can. Then disassemble and inspect, the strongest contact should be on the vertical surface in the frame where the back of the barrel lug vertical surface makes contact.

Since this barrel is a bull barrel with an integral bushing, the round portion behind the muzzle that wedges into the slide during barrel lockup should fit ok. If it fits to tightly and binds, remove a little metal from the top rear and the bottom front. It should lock up tight but without any binding, do not remove too much material as that will affect accuracy. You should have everything working smoothly and correctly now.

This barrel comes short chambered and will now have to be finished reamed to the proper headspace. With the barrel dialed in to center on your lathe or you may do this by hand, use the correct caliber reamer to deepen the chamber to the correct length. On a .38 Super that is .900 of an inch minimum. I usually go too .902 of an inch for powder fouling/case clearance and freebore the throat .200 of an inch to lower peak pressure in hot cartridges.

We are now ready to machine the face of the slide at a one degree angle so that the compensator has clearance to move freely as the barrel locks and unlocks during cycling. This lets the comp rear face fit against the front of the slide without a big gap. I screw the comp onto the barrel and the barrel into the slide, this way I can see how much material to remove to allow the barrel to go all the way back into the slide. I measure the gap and install the slide into my slide holding fixture; this fixture allows me to set the slide at a one degree angle, with the fixture square to the Mill vise. Or you can use a Starrett Angle Meter to set the angle of the slide face to one degree. I slowly machine the face of the slide back until full contact with the end mill goes from the top to the bottom of the face. I then trial fit the barrel and comp into the slide and see if any more metal needs to be removed with the comp orientated correctly. You will want to be sure the barrel is completely all the way back and in full lockup in the slide. The comp should be lined up correctly with the slide and the rear face of the comp should just miss contacting the slide face. That is in full lockup of the barrel, you may have to machine the slide face back a little more to achieve this fit. You want the comp and slide to look like one piece when in full lockup, but not touching each other.

I then clean and degrease the threads in the comp and on the barrel, install the slide and barrel on the frame with a slide stop in place. Apply Loctite # 638 Retaining Compound to the barrel threads and screw the comp on to the barrel. Use a Q-Tip to remove the excess that runs out. When the comp gets screwed on close to the slide face, move the slide forward into full barrel lockup and square the comp with the slide sides or flats. Set aside until it cures completely, I wait 24 hours to be sure, but it sets up fast. When cured out you can now blend in the top and sides of the comp to match your slide.

I now machine the spring plug tunnel for the reverse plug, on a comp gun I do that now so I can shorten the front of the plug to match the one degree angle we machined on the face of the slide. If you are using a collar plug, measure the thickness of the collar flange and with the slide level in the mill vise, remove that amount from the back of the spring plug tunnel. If you are using a stepped or integral reverse plug, an EGW reverse plug reamer (#296-108-100) makes the job easy. Run the reamer in from the back of the spring plug tunnel until the back of the reverse plug is flush with the back of the slide plug tunnel. Then with the spring plug installed, set the slide in your padded vise and file down the front of the spring plug flush with the face of the slide.

With that done I take the barrel and center it in my lathe. Using an EGW comp reamer, I ream the bullet exit hole .020 of an inch over bullet diameter. This reamer has a long pilot on it to center down the bore before the cutter ever reaches the comp, guaranteeing perfect alignment with the barrel bore.

Fitting Fire Control Components

The Caspian Hi-Cap frame comes with a trigger and I polish the sides and back on a hard felt wheel to a mirror finish, deburr the rest of the trigger with a needle file. Use a needle file and a trigger track stone to polish out and deburr the inside of the frame. I also polish the sear, disconnector, and hammer on a hard felt wheel with 555 polish to a mirror finish on the wear surfaces.

I install the sear in a Brown sear jig and stone down the top of the sear until it is even all the way across its width to a mirror finish with a Ceramic ½ inch square stone. Use the .020 of an inch thick shim on top of the jig for your stone to ride on, for the correct angle. I super glued my shim to the top of the jig, so it does not move around or fall off. When it begins to show wear I just replace it. Don’t remove too much here, just enough to make it even. Then take the sear and set it on a wide 2 inch hard Arkansas stone nose down, with the flat on the sear against the stone. Lift the back of the sear up about .020 of an inch, and stone the break away angle into the sear at a 45 degree angle. You want to have the break away angle width almost as wide as the top engaging surface. Use a ½ inch Ceramic stone to very slightly remove the sharp edge off of the intersecting line at the top.

Next I set my hammer in a padded vise and with a .018 of an inch feeler gauge in front of the hammer hooks I file down the hooks with a hammer squaring file. When the file just touches the feeler gauge strip, stop filing and finish up with your Ceramic stone. Now with your Ceramic stone polish the face of the hammer hooks and make sure they are kept square. Deburr the hammer sides and hooks, and then polish the sides of the hammer on your hard felt wheel. Polish the disconnector top and lower wear surfaces also.

I use a Brown 19 lb. mainspring and cut ½ coil off both ends, make sure the inside of the mainspring housing is free of burrs, and lube and install the spring into the housing. With the three leaf sear spring I flatten the curve at the bottom of the spring almost straight to remove some of its tension. Now hold the spring straight up with the 90 degree end on the left side and pointing up. That leg rests against the sear. And should ALWAYS be forward of the other two legs of the spring. You can bend the center leg, which rests against the disconnector and the sear spring leg to adjust trigger pull weight, but the sear leg should be forward of the other two legs. Too light of spring tension against the sear and you will have double fires or worse full auto fires. Don’t be unsafe with your trigger job.

Also too light of tension against the disconnector won’t push it back up when the pistol cycles.

Fitting the Grip Safety

The Caspian grip safety that comes with the Hi-Cap frame requires a .250 of an inch radius on the back frame tangs. I use a Brown jig to file the tangs down and then fit the grip safety to the frame. You can paint the tangs with a black felt tip marker, install the safety and move it up and down thru its travel to see were metal needs to be removed. When the thumb safety pin will go thru the frame and the safety will move freely you are done.

Next you will want to fit the frame radius to the grip safety. This is the part of the frame that sits on the web of your hand. You will want to file the frame edges so they blend into the concave radius of the grip safety. I use a round fine cut file to blend them together with the grip safety pushed down into the frame, so no edges of the frame are higher than the grip safety. You will want to blend in the top of the grip safety to match the top of the frame also. This is a good time to put the slide/barrel assembly back on to the frame, with the slide stop pin installed. With the slide all the way forward, you can blend the slide to the frame if you have any overhang of the slide. Now that is done and with all files marks smoothed out, disassemble the slide from the frame. Deburr the inside of the frame where you fitted the grip safety and the grip safety itself.

The tang on the grip safety will have to be fitted to the trigger bow. So you can now install the trigger components into the frame. Slide the mainspring housing into the frame to hold the sear spring in place. The tang on the grip safety blocks the trigger from moving when the grip safety is not depressed, usually the tang is a little to long and will not go down far enough to fit behind the trigger bow. Install the grip safety into the frame and hold it in place with the leg of the thumb safety. Now cock the hammer and with the grip safety pushed inward, the hammer should fall. And of course with the grip safety outward, the tang should block the trigger from moving far enough back to release the hammer. If it does not go down far enough to block the trigger from moving, you will have to file a little off of the end of the tang, to allow it to fall down behind the trigger bow. The key here is to go slow and check often so you don’t remove too much from the tang. Sometimes you will also have to remove metal from the bottom of the tang arm if it drags on the top of the trigger bow when fully depressed.

With the grip safety fitted and working properly, you can fit the ejector on the frame. Trial fit the legs on the ejector down into the two holes on the top of the frame; you may have to remove a little metal off of the legs for them to go down into the frame holes. With the ejector in place on the frame, use a 1/16 inch pin punch thru the hole on the side of the frame. And gently tap it with a hammer, it will leave a mark on the leg where you will have to file a groove for the retaining pin to go into the frame and hold it in place. I use a 1/8 inch needle file to file the groove. Now we can fit the thumb safety lug to the sear.

Fitting the Thumb Safety

Remove the grip safety from the frame, but leave everything else in place. With the hammer in the cocked position, you can trial fit the thumb safety to see if it will go into the frame, with the lug on the inside of the safety fitting behind the sear. It should be too long to fit and a little metal will have to be removed from the lug. With the safety still in place and the lug resting on the sear, I use a long needle to scribe a line on the inside of the lug. This shows how much metal needs to be removed and at what angle.

This is generally a lot of trial and error fitting so go slow, and check your progress often. It should fit behind the sear with slight contact to prevent it from moving. Once fitted, check it with the hammer cocked and the thumb safety on. Pull the trigger and there should be No movement of the hammer. If there is you have removed too much from the lug and will have to start over with another thumb safety. No errors allowed here!

Now you can fit the firing pin, with spring installed down into the firing pin hole on the slide. Depress the firing pin down into the hole several times to be sure it does not bind or stick. If it does, deburr the hole in the slide so that it works freely.

Assemble the magazine catch lock into the magazine release and into the frame. These should fit ok with a slight deburring, sometimes the catch lock ear drags inside the frame and the corner needs to be filed down.

Fitting the Extractor

Most match extractors have a bevel filed on the bottom of the hook where the case rim feeds into the hook. If yours does not, use a 1/8 inch square needle file to bevel that lower edge. It helps the rounds feed up into the extractor more smoothly. You will have to bend the extractor for it to have the right amount of tension. It should hold a loaded round against the breech face, without the round drooping down. Now that the tension is correct, polish the tip on the extractor and make sure there are no burrs.

Drill and tap the frame for the red dot scope mount you are using and mount your red dot on your pistol.

The Caspian mainspring housing comes smooth, so I checkered it by hand 30 lines per inch for a better grip. I also angled the magazine release button to fit my trigger finger, as I shoot left handed and use my trigger finger to release the magazine. It was also checkered 30 LPI.

That completes what is needed to do; now we can completely assemble the pistol with everything lubed up with your favorite gun oil.

Function test the feeding with dummy rounds and make sure All of the safeties work properly. Works great doesn’t it!

Now you can head to the range for live fire testing and sighting in. I load only two rounds at a time at first testing. When you know that everything is correct and functioning properly; you have finished building your first Race Gun. Have fun and Be Safe!

Recommended Tools
Ed brown Sear Jig #087-000-011
Brownells Trigger Track Stone #080-721-230
Brownells Slide/Frame File #080-753-000
Brownells 1911 Auto Lug Fitting Kit #080-000-089
Brownells Barrel Locking Lug File #080-751-000
Brownells 1911 Auto Barrel Holder
Brownells 1911 Barrel Alignment Block #080-000-041
EGW Hood length Gauge #296-000-055
Brownells 1911 Hammer Squaring File #080-811-001
Brownells 1911 Hammer Slot Stone #080-625-002
Loctite # 638 Retaining Compound #532-000-008
D&J Slide Milling Fixture
EGW .38S Compensator Alignment Reamer
Cominolli Frame Bridge Milling Fixture
Weigand Combat Scope Mount Drill Fixture
Brownells 6’x ½ x ½ inch Ceramic Stone #080-721-604 Fine, #080-721-601 X-Fine
6 inch Smooth Mill File #191-084-160
Bench Stone Hard Arkansas #975-005-008
Spyderco Ceramic Bench Stone #824-302-001
30 LPI Metal Checkering File #080-310-411
Manson Floating Reamer Holder #513-054-001
Reference Books
The Colt .45 Automatic #924-200-045
M1911 Pistol Manual Volume II #924-800-245
Ed Brown 1911 Bench Reference #087-000-002

Parts Used
Caspian Hi-Cap Frame #168-000-008
Caspian .38 Super Slide #168-000-050
Schuemann Hybrid Barrel .38S #836-011-160
EGW Hybrid Style Comp #296-114-101
Aftec Extractor #466-001-038
Clark Custom Two Piece Guide Rod #181-117-105
Ed Brown Slide Buffers #087-805-006
STI Titanium Hammer Strut #791-105-100
STI Match Grade Sear #791-101-110
Weigand Lightweight Hammer
EGW Aluminum Magazine Well #296-016-100
Caspian Scope Mount
Ed Brown Perfection Disconnector #087-000-040
EGW Extended Ejector #296-100-038
EGW Oversize Slide Stop #296-104-001
EGW Compensator #296-114-101
Ed Brown Mainspring #087-045-919
Wolff 9 lb. Recoil Spring #969-419-090
Ed Brown Hardcore Sear Spring #087-825-100
STI Titanium Firing Pin #791-104-138
Ed Brown Pin Kit #087-814-000