It was a
little over a hundred years ago that WW1 began. Being a firearms enthusiast, at
the start of 2014 Voland began collecting WW1 main battle rifles. It will be
interesting to systematically examine the designs, of these rifles, and through
them get a feel for the Era. A great deal of inspiration for these series of
post was from visiting two museums, The Deutsches
Museum in Munich Germany and the Heeresgeschichtliches
Museum in Vienna Austria. Seeing the manufacturing machinery, tools, and
working conditions of the Industrial revolution in the first, and in the second
seeing the morbid and fascinating exhibit dedicated to WW1.
Rational: The purpose of this
experiment is to evaluate WW1 era bolt action magazine fed rifles with an unbiased
and quantitative approach. It is proposed that the Finnish M39 WW2 bolt action
rifle is used as a reference standard for the evaluation. The rational for use
of the M39 rifle is as follows: The original design is from 1891, as such the rifle
represents WW1 era design and machining capabilities. The M39 rifle is of
exceptional quality, fit and finish. The M39 rifle cures many of the defects of
the M1891 Mosin Nagant, and represents a refined finished product. The idea is
to use a post WW1 rifle as an external reference standard.
Criteria for
evaluation: The M39 will have a score of 5 for all of the categories, for a
total score of 25. Each category has 5 evaluation criteria. A rifle feature that
is worse than the M39 gets a -1, same gets 0, better get a +1.
1)Overall
characteristics
a.Weight
b.Length
c.Comfort
(I.E. grip, carry, sharp edges)
d.Sling
points
e.Mud
(I.E. how easy is it to get mud inside the action)
2)Bolt
a.Locking
b.Speed
of manipulation
c.Safety
d.Re-cock
capability
e.Gas
escape
3)Firing
a.Sights
b.Trigger
c.Reload
d.Ammo capacity
e.Gloves and gasmasks (Use of the rifle with both)
4)Disassembly
a.Tools
b.Ease
c.Number
of parts
d.Reassembly
e.Parts
to lose (Can we send a spring flying)
5)Manufacturing
a.Complexity
of components
b.Costs
c.Cartridge
d.Repairs
e.Total
number of parts
Note: Accuracy is absent as a criteria. It is
impossible to accurately ascertain the accuracy potential in an unbiased and
universal fashion. Rifles will be ~100 years old, and there is no way to
account for wear. Also ammunition of original quality is no longer available.
As such accuracy will be briefly considered as part of manufacturing criteria.
Note: Bayonets
will not be evaluated. Maybe at a later date.
Addendum 1; Recoil has been removed as irrelevant. Use of rifle with Gloves and or gasmask has been added. A far more important aspect of rifle use.
Hello everyone, as I had promised earlier, here is the last chapter in the RPD build - Putting It All Together. In the previous 3 parts, we have made necessary modifications and have assembled all the subsystems of the RPD, and now comes the time to fully assemble the rifle and do some test firing.
We begin with the buttstock.
Onto which, the lower is installed.
Then, we install the handguards, and fasten the mounting bracket. Make sure to apply some thread locker to these.
This is what it looks like with the topcover and feed tray installed. To foreshadow a little bit, the top cover will need a little bit more fitting, but this will only be realized later.
And after all that work, here is what we finally get:
Some closeups of the individual builds:
The test-firing went smoothly for Chapaev's build, but the non-fitted top cover made itself be known for Voland's build. Now that we know the cause of the hickups, it will be fixed in short order. But without further delay, here are the videos.
Hello everyone, it's been a while since the last update. I've got a tiny bit of material to share with you before finally finishing the RPD build (it's coming).
Today we will talk about the differences between old style and new style Polish underfold parts. The differences are minor, but make for an interesting study in evolution of AK production. Before proceeding any further, I must give credit to Eric Fordon of theakforum.net for a great insight of the subject matter contained in this article.
In general, newer parts are machined, while later parts are cast with minimal machining. Here are two front sight blocks (new = top, old = bottom). Notice the casting marks, as well as some lightening "cuts" on the new style.
Here are the gas blocks. On the left is the new style, while on the right is the old.
Here are the lower hand guards. The old style is the darker one. Notice the metal horseshoe in the old, and the leaf spring in the new. Also, the old style has a serial number on the left side. The wooden tab that goes into the receiver under the barrel may be thicker on the old style.
Here are the hand guard retainers. The old style is on the left, and is milled, while the new style is on the right and is cast.
The slant breaks. The old style is on the right, while the new style is on the left. Notice the lack of what I am told is a wrench slot in the old break.
The return springs. The new style, with an anti-unlock tab is in the back, while the old style is in the front.
The rear sight blocks. RSBs are more or less identical, except for the rivet on the gas tube retainer. The old style is on the left (with a more protruding rivet), while the new style (with a flat rivet) is on the right.
Here are the top covers, but honestly I could not see much difference between them. This pair is the most distinct that I could find, with what I presume to be the old style on the bottom and the new style on the top.
Here are the trigger guards. The old style is on the left, and the new style is on the right. Notice the hump on the new style.
Here are the rear trunnions, this is probably the largest difference in parts between the old and new sets. The old style trunnion is fully milled, while the new style is stamped/bent and spot welded.
And finally, here are the folders themselves. The new style has 5 spot welds, and unequal length indents (on both sides of the spotwelds), while the old style typically has 3 spot welds and equal length indents (they look a unequal in the picture for some reason). There is an additional possibility of a combination of 5 spot welds and equal indents (not shown), it was seemingly produced under the new procedure using old parts. The loops in the bottom picture are different too, the left one being the new style, while the right one (with spotwelds) is the old style.
These are all the distinctions I could find, but I suppose I could have missed one or two :) so please don't take this to be an exhaustive list, simply what I had seen and taken pictures of.
In this post we will cover the modifications to the lower and FCG. The FCG was purchased from Project Guns.
Disassembly.
Firstly, strip all the wood from the lower. Knock out the trigger pin first, and remove the safety and the safety spring.
The lower will need to be cut to length.
Here is a blueprint that we will use for the next few steps. Refer back to it for dimensions as you read further.
First, mark the location of the trigger bar channel cuts. Then some material was taken out from the trigger bar channel using a dremel, so as to have less material to mill out. Be extremely careful when doing this. There is nothing wrong with milling out the entire area either, it just takes a little longer.
Using a machinist square, mark the length of the sear pocket and the overall lower length. You can see the final markup in the second picture (the front has already been sawed off).
Now, we are ready to do some mill work - clean up the front of the lower, mill out the sear pocket, mill out trigger bar channels, mill out the round trigger bar relief. Hold the lower as shown below, and align the z-values along the x-axis, also double check consistency of y-values as x-axis is traversed.
The trigger bar channels are cut using a 1/8 carbide end mill. To start the
cut - touch off on the inside of front cavity (the longer narrower one)
and cut (in several passes) towards the stock. 0.125" is a sufficient
width for the channel and further widening is not necessary.
The sear pocket is milled out using a 1/4 end mill. For trimming the front, we used a 3/8 mill, but any large-enough cutter will suffice.
The following picture, shows the (almost) finished product. There is still one more cut remaining - it will be done shortly.
We can now start fitting the lower to the receiver. Using a small file, round the front of the lower as shown in the picture.
Additionally, these areas of the receiver will need to be rounded to mate with the lower.
The charging handle also needs a little filing. The areas that need to be filed are circled in red in the following picture. Also, give the flat area on the top a little work with some sandpaper.
Here is the fitted assembly.
Having fitted the lower, we can now drill the pin holes for the FCG. Here is a blueprint that we used. It is based on the blueprint was originally included with the FCG, however some values have been updated to fit the included parts. Refer to this picture for dimensions as you read the description below.
Here is a picture of the FCG itself, which includes: new rear pin, new barrel pin, screws for installing the drum bracket, trigger spring, striker, striker spring, FCG pins (there are 4, though you will only need 3), trigger bar (contains sear and disconnect), trigger bar spring, firing pin extension and firing pin extension cross-pin.
If you install the trigger bar, you will notice that it rubs against the lower in the area shown.
To accommodate this, we will mill out a relief cut in the lower. This is an inexact cut, as it is difficult to fit the ball end mill into this particular area of the lower. Using a 1/2 ball end mill, cut as long of a cut as you can manage, down the centerline of the lower. The total depth of the cut is 0.015".
Here is a picture of the trigger bar installed. Make sure it is free to move back and forth.
The trigger needs to be modified, in order to accept a trigger spring. This is accomplished by making two cuts using a 1/4 end mill. The first cut, 0.050" deep, starts from the center of the existing trigger pin hole and proceeds in a direction that is perpendicular to the nearest edge. The second cut, 0.100" deep, also starts from the center of the pin hole but proceeds at a 45 degree angle to the first. You can see both cutting directions marked in this setup picture. Center on the hole and proceed in light cuts (~ 0.010" per pass) from the center outwards.
The first cut is done.
We now, realign the trigger along the next cutting axis. Note the original mark is no longer visible, so we draw a new guide.
Center on the hole and proceed in small increments, as before.
Here is the finished trigger after some cleanup with a small file.
There is one more operation that needs to be applied to the lower - we need to drill out the return rod hole to 3/8. The setup is shown in the picture below. We use a machinist square rather than a test indicator for alignment due to the difficulty of getting the latter into the area of the measurement. The entire setup is extremely vibration-prone, since we're holding the lower by a (thick) piece of sheetmetal. For this reason it is very important to drill the hole in increments and at a small feed rate. We drilled first to 11/32 and then to 3/8.
Finally, a chamfer is applied using a scraper - a ground down triangle file.
Installation of the trigger and its spring reveals that the spring is rather long and will need to be cut to length.
Mark the area where the spring touches the lower, and using a dremel cut-off wheel make a groove just deep enough to hide the spring wire. Cut the spring to length -- careful here, cut it purposefully long and then trim to fit.
Without going into chronological detail as to how these locations were identified, I will simply show you which areas of the trigger bar were making too much contact with the trigger and its spring. You will need to file these areas just enough to clear the binding. (You will also need to file the trigger itself, so don't focus on the trigger bar alone.)
In the following picture we can see the areas of the trigger nose that will need to be fitted.
To fit the trigger, you will need to remove a significant amount of material from the top of its nose, as well as the sides of the nose (see pic below). Additionally, you will need to polish these areas to a shine, in order to ensure a smooth function of the disconnect. The entire thing must operate smoothly, no matter how hard you pull the trigger.
Here is a picture of the finished trigger.
Here is a picture of the fully-assembled FCG.
And here is a video of the FCG in action (sorry about the blur :) Stay tuned for the next post, where we will put the rifle together and do some test firing.
PS. In case of Bubba, break glass -- a short story.
Without going into details as to how this occurred, other than to say -- no it wasn't me, the lower which I had been painstakingly working on for so long was scarred by Bubba's favorite weapon - the dremel.
This was very upsetting, as the whole thing was almost finished, only to receive this horrible mark. I did not want to weld, as the location of the gauge was very close to the FCG pin hole... but how else to fill this void? And then it hit me -- soft solder. The location of the gauge is on the bottom of the lower (not a critical area) and it will be finished by parking followed by dura-coating, so there really should be no difference in the finish once the paint is applied. Here is what to do. Apply a generous drop of soft-solder to the damaged area.
Using a MAPP torch heat the solder from below, otherwise the gas pressure ends up blowing away bits of the solder. Once it melts, let go of the heat, and check for air bubbles and small voids in the filler. If necessary apply another layer of solder and melt it again. Once satisfied, take a hand scraper (like the ground triangle file from before) and scrape the bulk of the solder off. Follow by a sandpaper polish, and you will have something that looks like this:
