Drop In or Not?

by Bob Londrigan, published in Front Sight Magazine, March 2008

There are a multitude of parts available for the 1911, and many shooters assume that any part advertised as fitting a 1911 will just fit right in without any problems.  However, it doesn’t always work that way.  In fact, it doesn’t work that way most of the time.  There are many manufacturers making 1911 clones and each of them has a slightly different blueprint.  This means critical dimensions on guns will not only vary from manufacturer to manufacturer but also from lot to lot.  Add in the fact that there is also a very large aftermarket parts industry (this is one of the pluses to owning a 1911).  As with the guns, each parts manufacturer makes these parts to their own set of blueprints and, again, each set of blueprints is slightly different.  The end result of these varying dimensions is many parts will not just drop-in.

One thing that causes problems is that parts manufacturers must make their parts so that they will fit the majority of guns with as little work as possible.  As a result, the parts may fit some guns with a sloppy fit, others will fit just right, and in still other cases the parts may not fit at all.  The alternative to this is what are called “gunsmith fit parts.” These parts are somewhat oversized in critical areas and will have to be “fitted” by filing, cutting, milling etc. until they exactly fit your particular gun.  This results in a better fit but takes more effort and expertise. What I will cover in this article is how much gunsmithing knowledge and expertise, as well as how many tools are needed to make some of the more commonly installed after-market parts work in your gun.

I am splitting these replacement parts into three categories based on the types of tools that you will need to install them:

• Group 1 – Requires only basic inexpensive tools

• Group 2 – Requires specialized tools to do the job right

• Group 3 – Requires a mill for best results

Group 1 includes the following parts:

• Mag Button

• Guide Rod

• Springs

• Magwell

• Firing Pin

• Mag Release

• Mainspring Housing

• Recoilmaster Guide Rod

• Firing Pin Stop

• Trigger

• Slide Stop

• Disconnector

• Ejector

• Extractor

• Sights

• Thumb Safety

The parts in this category are fairly easy to install if you have a basic set of tools and are able to break down your gun completely and then properly reassemble it. Installation of many of these parts has been covered in previous articles – check your back issues for in-depth coverage or go to www.brazoscustom.com where we have archived most of the articles. The chart below will give you an idea of the relative ease of installation of each of these parts based on my personal experience in installing them.  I’ve rated each part from 1 to 10 where “1” is the easiest to install and a higher number is progressively harder to install.  Each part is rated relative to the following four factors:

Technical expertise or knowledge of how to install the part – much of this knowledge can be gained by reading previous articles from Front Sight.

Proficiency with tools – some installations require a better proficiency with tools such as files, measuring devices, etc.

Variation from part to part – how much this particular part varies dimensionally from one manufacturer to another and, to some extent, how much variation there may be from part to part from the same manufacturer.    More variation will require more expertise on your part to know how to adjust the part to make it fit.

Variation from frame to frame or slide to slide – critical dimensions on the slide or frame that vary will make installing the part harder (you must adjust the parts to fit).  Some parts are more susceptible to this problem than others.

 If you decide to tackle some of these installations, here are some tips relative to each of the above parts:

•  Mag button – The key here is to make sure your mag release is drilled and tapped, most buttons have 4-40 threads.

•  Full length guide rod – Make sure the head fits flush in the frame impact area.

•  Springs- For recoil springs going into a reverse plug make sure the compressed stack height of the spring will fit in the recoil spring plug.  Otherwise it will try to push the plug out the front of the slide.

•  Magwell – This will usually have to be blended with the frame for best performance.

•  Firing pin – Make sure it fits the firing pin hole without dragging.

•  Mag Release – Make sure it cannot be over inserted and bind the magazine.

•  Mainspring Housing – Pin alignment with the frame is often a problem.

•  Recoilmaster guide rod – A relief needs to be cut on the bottom of the barrel for the head of the Recoilmaster, and the frame and slide need to be trued where the head of the Recoilmaster contacts them.

•  Firing Pin Stop – Fit it to the slide first and then to the extractor.  Be aware there are oversize firing pin stops and regular size firing pin stops. The oversized type are wider left-to-right to stop the extractor from rotating in its channel.

•  Trigger – Make sure it slides freely in the frame and that there is no contact between it and a magazine when a magazine is inserted in the gun.

•  Slide stop – The diameter of slide stops will vary from manufacturer to manufacturer and lot-to-lot, and dimensional changes as small as 0.001 inch can make a difference in your barrel fit.  Test the slide stop for fit in the hole in your frame and then test the barrel fit with just the slide/barrel/frame assembly.  There barrel should lock up just like it does with the old slide stop -- no hitches or hard spots.

•  Disconnector – Length of the disconnector can cause problems with your trigger function.  Be sure to test the trigger for proper function after a disconnector install.

•  Ejector – The nose will need to be shaped for proper ejection clearance.

•  Extractor – Tension will have to be adjusted and it will have to be fit to the firing pin stop.

•  Sights – Front sight dovetails will vary quite a bit.  Depending on the sight and the slide, it may take quite a bit of fitting.

•  Thumb safety – You must understand how the safety works to adjust the stud that engages and blocks the sear.  Every safety is made with extra material there and will need to be adjusted.

The next category of parts are those that require specialized tools and a higher level of expertise/knowledge to install properly.  I would recommend that you start with some of the parts we mentioned in the first section before you try to tackle parts in this second category.  The tools needed to install these parts are fairly expensive, so if you are only going to install one part it will not be cost effective.  You will be better off sending the gun to a competent gunsmith to do the install.

Parts that fall in this category are: hammers and sears, beavertail grip safety, and barrels.  The exception to this would be parts that have already been prepped, or in the case of the beavertail, if your frame already has the 0.250 radius cut needed to use a beavertail.  A switch to a beavertail will also require use of a commander type hammer for clearance. Be aware, drop-in hammers, sears, and barrels may still cause you problems depending on how close your gun is to blueprint specs.  Especially on hammers and sears, it does not take much variance to cause problems.

The third category of parts are those that require a mill to install.  These would be front and rear sights (when you have a bald slide or a staked in front sight) and fitting a new slide to a new frame. In fitting a slide to a frame you may be able to get away with files and lapping compound if the parts are within 0.001 or so.  However, any more than that and you will be taking a good chance that you will ruin your slide or frame.  Leave these types of installs to the experts unless you are ready for the challenge.

If you realize that all parts are not created equal, go slow, measure often, and know your capabilities, then there are many parts that you can install yourself.