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Build Your Own Gun Project

By Bob Londrigan, First Published in Front Sight Magazine, July 2021


Building your own gun from scratch can be an extremely rewarding undertaking, but at the same time it can be overwhelming trying to start the process. The tools needed can be expensive – costing more than the gun itself if you tried to buy everything at once. The concept for this article is to walk you through the procedure on how to build a complete gun without the use of a mill or other expensive tools. You should be able to complete this project with simply basic tools that you probably already have in your toolbox. I am not going to go into detail on the installation of the parts but focus more on the procedure itself and the order in which parts should be installed. I will break the job down into smaller pieces, so it is more manageable and not so overwhelming. I will approach the project assuming you have never built a gun before (if you have it will just make the job easier.)

In order to build this gun with simply basic tools you need to start with a base that has some of the work already done. The product that I will use for this project is a limited gun style shortblock that has the slide lightened and the sight dovetails cut. This is more expensive than just starting with the parts, but it will save you a lot of work that is usually done with expensive tools.

A shortblock consists of a frame, slide, barrel, and slide stop that have all been fitted. The barrel has been chambered, crowned, and the feedramp cut. The link has been fit and the barrel timing set properly. (If you know how to do this work, you can save yourself some money by doing it yourself.) I will also make extensive use of drop-in parts and parts that have been pre-tuned. You do not have to use these if you know how to tune the parts yourself. Pre-tuned parts just make the installation easier for the first-time builder.

The first thing to do is to inspect your shortblock. Check the chamber – drop a round in and make sure it goes all the way in and does not stick. Check the barrel fit and slide to frame fit. They should be tight. Do not worry at this point if the slide or the barrel fit feels too tight. By the time you have built up the whole gun you will cycle the slide and the barrel many times and everything should break-in. If you get to the final test firing and things are still too tight you can use a little lapping compound at that time. The barrel crown should be clean and free from any nicks. If all this checks out we are ready to start building.

Check the slide stop to see whether it is setup for lockback. If you do not want the gun to lockback adjust the tang on the slidestop and drill a dimple. Now fit the ejector to the frame. A tuned ejector will have the nose cut for proper ejection, but you will still need to notch the front leg for the pin. Next install parts on the slide. Install the firing pin first, make sure it slides in and out easily with no drag. The firing pin stop is next, then the extractor. Adjust the extractor tension, and make sure you have enough clearance between the hook and breechface for reliable feeding. Install the rear sight - make sure the elevation screw does not contact the firing pin and bind it. Install the front sight. At this point your slide is ready to go, set it aside for later.

Next up is completion of the bottom end. Start by assembling the grip. Install the trigger and put the spring and pins in the mainspring housing. Also check the fit of the magwell and do any necessary blending. Install the mag catch release and check for smooth operation. Assemble the grip to the frame. It should go on snugly but not so tight that it distorts the frame. Bushing holes should line up and end up a tight fit when you get done. Now you will need to fit and blend the beavertail and thumb safety. For now, the safeties just need to fit in the gun. Once the safeties are in the gun hold the safeties in the down position and grind, file, sand, and polish the safeties until they blend in smoothly with the frame. Do this on the lower portion under the beaver tail first. This is one area where you will need some tools you may not have. A round file, Dremel tool with sanding drum and stones, and some type of polishing wheel. Then blend in the top portion. On the top, one thing to remember is, if your grip safety is functional, I like to blend it with the grip safety up (in the engaged position). This is my personal preference because I think it looks better but you can do it either with the grip safety up or down.

Now you are ready to fit your guide rod and plug. Not much to this, but I like to fit them at this point because I like to blend them in to match the front of the slide and dust cover for a nice flush fit. Now assemble the slide, barrel, slide stop, guide rod, plug and recoil spring. File the front end of this assembly so that everything matches. Then go to the back and do the same thing – you will likely have a slight mismatch of the slide, frame, and ejector that needs to be cleaned up. Take everything apart and clean well – get all the grit out from polishing and blending. Then put the bottom end back together without the safeties.

You are now ready to install the trigger components. This is one area where a tuned set is a good idea. If you get a tuned set the hammer and sear angles will be setup correctly and assembly/adjustment will be much easier.

Install the hammer, sear, disconnector, and sear spring. No safeties yet. Check overtravel, pre-travel, disconnector function, and trigger pull. Check for even contact on both hammer hooks. Adjust, as necessary. Now set up the grip safety. Once you are done take the grip safety back out. Cut the sear engagement tab on the thumb safety so that the thumb safety will go in the gun and when engaged the sear cannot move at all. Completely assemble all components at this point using a generous amount of oil everywhere on all contact surfaces.

Now for final testing and tuning. Rack the slide back and forth 40-50 times and check for any dragging or binding. If you find something dragging or rubbing that feels out of the ordinary stop and figure out exactly what is causing it and correct. Cock the hammer and make sure the thumb safety engages. Check the grip safety for engagement. Dry fire 40-50 times and make sure everything feels good. Insert a magazine and make sure it goes all the way in and locks in, make sure it drops free without binding. Once you have done all this you are ready to test fire the gun at the range.

One warning before you go to test fire the gun. Do not try and chamber a live round at your workbench. Make sure you are at the range and the gun is pointed in a safe direction. You do not want to have an accidental discharge while you are doing the initial test firing. The greatest risk of something going wrong is during the initial first few rounds of testing.

Make sure the barrel bore is clean and unobstructed. Load a magazine with one round only and test fire the gun. Do this for at least five rounds without any type of malfunction. If you have problems, stop, unload the gun, figure out the problem, and correct it. Start over again and repeat. Once you can fire 5 rounds one at a time start loading more rounds in the mag. Load 2 rounds and shoot, load 3 rounds and shoot, etc. Keep working at this until the gun is reliable. On your first try at building a gun you may have to quit and take the gun home to diagnose and fix any problems and them come back. Do not try and rush the process. It is easy to get excited at this point to be finished and rush the process. Take your time. Once everything is running smoothly, sight the gun in and shoot a group. I like 25 yards from a rest. Since the slide to frame fit and barrel fit were done professionally you should get a pretty good group if you do your job firing the gun.

Once the gun is running take it back to your workbench and completely disassemble and check for any unusual wear or dragging. Once you are satisfied everything is working properly you can take it apart and do a detail clean. The gun will need to be detailed to polish out any scratches it got during assembly and to get it ready to go for some type of coating. You can shoot the gun in the white for a while to make sure everything is the way you want it and then send it for coating. Just make sure to oil it on all surfaces to keep it from rusting while you are doing your final evaluation.


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