FBP bolt and recoil assembly - failure to eject issues

[imageaudio]

I'm running an FBP bolt and recoil assy in my MP40.  Used to work fine but now I'm experiencing some failure to eject issues which usually manifests as an empty casing inside the receiver that jams up the bolt system as it's attempting to load the next round.

I changed ammo which was a little hotter and it improved the issue but did not solve the issue.

Perhaps the extractor and ejector need replacing?   

Any thoughts of the workflow to identify the problem?   

[Rekraps]

8 hours ago, imageaudio said:

I'm running an FBP bolt and recoil assy in my MP40.  Used to work fine but now I'm experiencing some failure to eject issues which usually manifests as an empty casing inside the receiver that jams up the bolt system as it's attempting to load the next round.

I changed ammo which was a little hotter and it improved the issue but did not solve the issue.

Perhaps the extractor and ejector need replacing?   

Any thoughts of the workflow to identify the problem?   

Not having the unit in hand, always go the easiest route first: 1) Extractor 2) Ejector 3) Recoil spring

Lucky for us, the MP40 makes it easy to replace all three.

[Rekraps]

Hey, I posted this elsewhere, but tips on removing the FBP recoil assembly end plate (to remove the spring?) it has two small holes in it, obviously for a special tool that I don't have. 

[68coupe]

Rekraps, you should make one, and then you'll have it forever. I'm sure you're a vey resourceful guy. Study how it's supposed to come apart, and make a tool that does that for you. It has been my experience that such tools were made of unobtanium and must be reproduced.

V/R Karl, 68coupe

[Rekraps]

19 hours ago, 68coupe said:

Rekraps, you should make one, and then you'll have it forever. I'm sure you're a vey resourceful guy. Study how it's supposed to come apart, and make a tool that does that for you. It has been my experience that such tools were made of unobtanium and must be reproduced.

V/R Karl, 68coupe

Actually I did that for my SKS's, similar tool, so you are a wise man. I'll just make one (hard wood with two ten penny nails evenly spaced will do it!)

[Rekraps]

On 12/28/2023 at 12:54 AM, imageaudio said:

I'm running an FBP bolt and recoil assy in my MP40.  Used to work fine but now I'm experiencing some failure to eject issues which usually manifests as an empty casing inside the receiver that jams up the bolt system as it's attempting to load the next round.

I changed ammo which was a little hotter and it improved the issue but did not solve the issue.

Perhaps the extractor and ejector need replacing?   

Any thoughts of the workflow to identify the problem?   

I just reread your post, sounds more like an ejector.

[DINK]

FWIW, I would first examine the ejector to see if there's any indication of damage to the tip.  They don't break often, but it can happen.

Second, remove and examine the extractor.  Check the little hook for damage and clean it and the slot it rides in well.

Third, disassemble and examine the recoil assembly.  Those FBP bolts and recoil assemblies are pretty old now and who knows what kind of dried up lube is in there.  The telescoping sections can also get damaged and start binding if they get slammed to the rear too violently.  Make sure they slide easily.

Fourth, buy a set of Wolff springs and install them in the FBP recoil assembly.  The original springs were supposedly more powerful than the MP-40 springs and putting in a set of Wolff MP-40 springs is just cheap insurance to keep things running.

[Rekraps]

Shot the MP40 (bnz41 C&R) today using he FBP bolt and recoil assembly. Worked perfect! No modifications required.