Picked up my BNZ 43 MP40
- Thread starter Killerfish67
- Start date
Killerfish67
Well-known member
Now that would be fun!!! Is that just a regular suppressor with an adapter?
Bigdibbs88
"Ach du lieber!"
That is awesome! I need one of those
mostpeople
Senior Member
$25k cash for an mg34 is a steal, good job.
tsmgguy
Senior Member
Looks great!
If the barrel nut has never been removed, I wouldn't touch it. The locking ring is factory installed only once. This also means your factory targeting is undisturbed. Here's my bnz 41 all-matcing example. You can see that the original factory staking is intact. It's the only one I've ever seen that is.
The other problem with removing the barrel nut is that the flats will probably be boogered by a wrench that doesn't really fit.
If the barrel nut has never been removed, I wouldn't touch it. The locking ring is factory installed only once. This also means your factory targeting is undisturbed. Here's my bnz 41 all-matcing example. You can see that the original factory staking is intact. It's the only one I've ever seen that is.
The other problem with removing the barrel nut is that the flats will probably be boogered by a wrench that doesn't really fit.
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Killerfish67
Well-known member
I believe mine is the same way what do you think?
Attachments
Looks like the barrel has been off, but that’s far more the rule and it’s rare to find one with the original staking of the washer such that you know that the barrel hasn’t been off. From the factory it’s staked on both sides. That washer and staking keeps the nut and barrel from loosening in use.
biggymu
Well-known member
Original German WWII MP38 MP40 SMG Barrel Nut Lock Washer
Original Item: The barrel nut (berwurfmutter) of the famous German MP38 and MP40 machine pistols was locked in place by a thin steel lock washer that was peened into place after the barrel nut was tightened to the correct torque setting. These rings were usually ruined when the guns were...
www.ima-usa.com
These are reusable
tsmgguy
Senior Member
You'll see small square cut outs in the barrel nut. The thin steel barrel nut locking ring would have been factory staked into the cutouts. Can't see your pic very well so I'm unsure about this one. Looks like a very nice gun though, congrats!
tsmgguy
Senior Member
It’s just a lock washer. With the barrel snugged down. A punch or similar is inserted in the slot under the washer and it is distorted to fill the gap. This holds the nut from vibrating loose.Original German WWII MP38 MP40 SMG Barrel Nut Lock Washer
Original Item: The barrel nut (berwurfmutter) of the famous German MP38 and MP40 machine pistols was locked in place by a thin steel lock washer that was peened into place after the barrel nut was tightened to the correct torque setting. These rings were usually ruined when the guns were...
These are reusable
The barrel nut locking ring is reusable, yes, but once the nut is loosened it will not tighten to exactly index in the same place that it originally was. The rings also tend to get a little bent and wavey when reused rather than dead flat as they were when they left the factory.
True, MP40 barrel nuts are removable, but the Germans did not intend them to be removed by users. The MP40 was instead intended to be semi disposable. If it was significantly damaged, it was meant to be discarded and replaced. MP40s were not sent in for depot rebuilds, TTBOMK. They were meant to be the lowest priced option available at the time, with the lowest possible costs, from their design through materials and production.
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biggymu
Well-known member
Absolutely true. Yours looks to never have been disturbed. The OPs looks to have been removed at some point. The whole crux was to suggest a repop barrel instead of putting significant wear on his matching assembly should he desire to do so. A misfire can result in a bulge and so forth. These weapons are no longer considered semi disposable in any way at the current prices.
Killerfish67
Well-known member
If everyone is saying that my barrel is off I’ll probably invest in a shooter then I can honestly shoot it as much as I want and not have to worry about it. I have a FBP bolt in it for shooting. Is there any other part I should be wary of?
biggymu
Well-known member
The only part I ever had fail on mine was the cocking handle. The stamped outer piece flew off and I lost the pin, detent ball and spring. I was lucky enough to find a replacement set.
I have replaced my bolt with the early “wolfs tooth” MP38 style. The FPB bolt should have you covered. It is a simple and tough weapon.
The buttstock can wear and sag over time.
I have replaced my bolt with the early “wolfs tooth” MP38 style. The FPB bolt should have you covered. It is a simple and tough weapon.
The buttstock can wear and sag over time.
This. I've bulged a barrel, fortunately a barrel that was a shooter and raggedy anyway. The funny thing about the bulge is it caused the bullets to be unstable and keyhole out to about 10 yds, then they stabilized and were fairly accurate. The barrel is lugged into the receiver extension and that fit is where the accuracy and sighting in come from. The washers simply keep the barrel nut from loosening. On FBP parts in the MP40:
FBP bolt: sometimes the sear "ledge" is not at the proper angle (not steep enough) and will slip off the sear. This is a dangerous condition for an open bolt SMG. You'll have to the bolt sear step recontoured to be more steep, which will probably interfere with the hardness of that part so watch it.
FBP recoil tube: These can be shorter and with a narrower diameter end "point" which will jump out of the little cup in the back of the receiver for it and bind the whole operation. Sometimes it takes mixing MP40 tube ends with the upper FBP flat section for the FBP bolt. If you have too much flex in the recoil tube sections you'll get jammed up recoil tube sections. MP40 sections will not always interchange, just like the threaded firing pin / buffer sections on an MP40 may not interchange due to slight variances in the threads. The same is true of FBP parts.
Recoil spring: this and your ammunition are a key to reliable functioning. The hotter the ammunition the better. Stay away from Wolf type cheap 9mm as its usually under powered and will cause the weapon to "run away" and just go "plup plup plup" until the magazine is empty. The recoil in this ammunition is enough to eject the casing and pick up another from the magazine but not enough to engage the sear, thus a runaway.
Bullet feed angle: this is a key to reliable functioning. The magazine feed lips must allow the bullet to have a slight upward angle
Magazine spring: this is a key to reliable functioning and must support the bullet feed angle. Most period springs are worn. Many magazines have slightly deformed feed lips.
Ejector: this is key to reliable functioning. The factory originals were invariably ground on the face for the proper ejection angle and the ejector must be installed and fitted so that it rides perfectly in the bolt channel, does not interfere with bolt function, and at the same time is at the proper angle over a loaded magazine.
Extractor: this is key to reliable functioning. It must be the proper tension and have sufficient gap and grip on the cartridge. Test it outside of the weapon by slipping a cartridge in it. It should be held on its own by the bolt.
The MP40 is one of the best WW2 SMGs. However, all those parts were numbered because many of them required hand fitting, not because the Germans were anal. All parts won't interchange across makers without some fitting. Some will never fit, such as the slight differences in threads for the firing pin / buffer assembly, and recoil tubes. A factory original will usually run fine. However, I would put all my matching parts away and run a complete shooter set on my receiver. You'll never wear out or break an MP40 receiver. You can bulge a barrel, break a firing pin, pull off a bolt handle, break a bolt, break an extractor, break an ejector, break the bakelite on your lower assembly, etc.
Cheers,
HB
Killerfish67
Well-known member
Thank you guys so much for all the help it is greatly appreciated!!!!
The one thing it may be good for is suppressed firearms. A suppressor is going to create more back pressure for blowback function and that stuff is probably under 1080 fps, so it may stay subsonic.