Building The Russian PPs-43 Semi Auto
Contents Copyrighted

The PPs-43 bolt conversion

Often, the most difficult part of a semi-auto conversion is reworking the bolt. Sometimes they are hardened, making machining difficult. Frequently they are long and have a solid center, requiring the drilling of a hole all the way through for the firing pin. This is not an easy task as drill bits tend to wander off course!

I want to thank two Weapons Guild members, Rocco1911 and Little Rhody, for their work on researching much of the following information on making the PPs-43 bolt work reliably and safely. Much of my work in this area built off of their efforts!

In just about every case, a long slot must be milled on the outside to accommodate the BATF required blocking bar. This bar is there to prevent the insertion of an unmodified full auto bolt. The full auto sear notch must be removed or altered.

While many BATF documents say, if the original firearm fired from an open bolt and had a fixed firing pin, the lower portion of the feed lips must be removed - this BATF approved build was approved with the feed lips fully intact. I found I had totally unreliable ejection without them.

Bolt work.

First off is the blocking bar groove. It's right on top and it's there to clear the indented blocking rail stamped into the top of most PPs-43 (and KP-44) receiver repair sections. If your repair section didn't come with a blocking rail integral with it,
you will need to add one.

Here is a shot of a receiver of this type with the stamped in blocking rail This one is for sale from Military Gun Supply.

If you look back at the photo at the top of this page, you can see the corresponding groove or slot on the top of the bolt. It is 1/4" wide and deep enough for clearance. Mine is a finished depth of 0.090

As discussed in the section on the fire control group, I had to remove part of this blocking rail and replace the removed portion, farther forward in the receiver, with a bead of weld. This was done to gain clearance for the hammer to swing through this area. The open slot was hidden by welding the rear sight over it.

The weld bead shown here was later ground down to the size and shape of the original portion. Replacing this cut out section was required by the BATF and they informed me that the final product had to be re-submitted to them for approval. My approval will transfer on to you as long as you do the same thing in the same way.

On the bottom of the bolt is a groove to clear the hammer in the Remington 870/11-48 fire control group. This has become pretty much the standard FCG for this build. This groove needs to be deep enough to reduce friction between the hammer and the bolt during recoil. I cut mine .100" deep by 1/4" wide and full length of the bolt.

Some metal may also be ground off of the face of the hammer, but don't lighten it too much or remove much from the point where it strikes the firing pin rod.

Please note that the entire sear catch notch has not been removed yet on this bolt.

Another thing required by the BATF is the removal or alteration of the sear notch on the bottom of the bolt. My personal policy is to completely remove this sear area so no one can re-cut it at a later time. Here is a shot of me milling the sear notch completely off.

And here is the final form of the bottom rear of the bolt with the sear notch completely removed.

The final, and most difficult of the modifications to these bolts is the firing pin system.

First, the fixed (but removable) firing pin is removed. This firing pin is held in by a small projection on the the extractor. This projection must be 50% ground off so as to preclude using it with a fixed firing pin in the future. Note - it is ONLY the smallest and lowest projection that is removed!

The old firing pin hole is then threaded and a bushing is screwed and LocTited in.

Here is a shot of the original firing pin, extractor and spring.

And here is a shot of the firing pin bushing installed in the old hole.

Before drilling, there's a small shelf inside of the hole where the rear of the firing pin is. It will deflect your drill,so it must be removed. I come in through the round hole on the side (where the extractor is - see photo above) with a 7mm end mill and barely remove this shelf prior to drilling. Be careful as it is easy to come right on through the other side of the bolt as the side wall is thin here.

Next, the front of the bolt was drilled through, all the way to the hole for the recoil spring cross rod, with a #16 drill. It is then threaded 12-24.

A 1/2" long, 12-24 thread, socket head cap screw is used to make the bushing. It's drilled all of the way through with a 5/64" cobalt drill and then back drilled 3/4 of the way with a #36 drill.

Following this, the head of the screw is sawed off and the end is carefully ground flat.

The bushing is then coated with red, high strength thread locker - I use LocTite. Carefully screw the bushing in until it is flush with the face of the bolt. Let it sit undisturbed for 24 hours to cure. If you ever need to remove this bushing, heat the entire bolt slowly to 500 degrees F and unscrew it with an Easy-Out.

Here's a view of the components making up the firing pin system. There is the firing pin, the rebound spring and the transfer rod that bridges the gap in between the firing pin and where the hammer impacts the rear of the bolt. There is also a small retaining pin that holds everything in place.

It all starts with the firing pin. I made the FP body from #17 drill rod. One size smaller than the hole, for clearance. The front pin part is a 5/64: drill bit cut off to 1 1/8" long. This will leave a small portion with the drill flutes on it. I fill these with green LocTite high strength "Sleeve Retainer" NAPA part number 765-1149. The flutes ensure an adequate amount of LocTite in the hole. Gently turn the drill shank and move it in and out some while seating it to ensure good inside coverage.

Later you will need to adjust the length of this small pin, by grinding, to get proper protrusion for reliable but safe primer ignition. Make sure you have a nice smooth shape to the tip of the FP.

The rebound spring is one I ordered from Century Spring Corp. It is part # L-93. They have a $40 minimum order

Not very well shown is the groove in the transfer rod for the cross pin, the cross pin and the hole for it. The hole and groove may be located just about anywhere along the transfer rod.

Here I am lathe boring the rear hole. I am using a 6” long 7/32” cobalt aircraft bit to drill with.

Due to the shape of the front of the bolt, I had to make a custom carrier to hold the bolt in the three jaw chuck.

Here is the carrier sitting on the bolt. Precise machining is needed in order to get the bolt properly centered in the lathe.

No – before you ask – I don't want to make another one!

Finally, the recoil spring stop must be opened up to allow the firing pin to pass through it. You can either slot it or drill it. I used a 14" chop saw to cut these slots. It took two setups and cuts to get the right width.

If you drill it, the firing pin will capture the spring stop and they will go in and out of the gun as one unit.

At this point, the worst part of the build is over.

Return to Home Page