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Discussion Starter · #1 ·
Has anyone ever experienced this before? My war booty 1941 Izhevsk was discharged today when out of battery although the firing pin spring was (is) going strong. The receiver rear took some damage and is now slightly tilted backwards.

More to follow. :(
 

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CH: I've posted threads on forums up here in Canada asking SVT owners if they've had serious mechanical problems like what you experienced. I figured with a lot of the recent refurb imports being actively shot by (in part) non-sympathetic owners it might have revealed issues. So-far nothing has surfaced.

Ruprecht
 

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Discussion Starter · #5 · (Edited)
Thanks for replies.

I started shooting using my own handloads which all worked fine. I shot 35 rounds. The bullets were 124 gr Lapua S405 (.310") powdered by 2.95 grams of N130 which is roughly midrange load. I had S&B primers which are soft but I've never had troubles with them in Tigr or SVT as both have spring-loaded firing pin.

When I had finished shooting an older fellow wanted me to try his reloads. I wasn't really thrilled but didn't dare to refuse. He gave me two rounds first which I looked pretty closely. Brass was a bit tacky somehow (dried case lube?) and I asked him what powder there was in the cases. He told me it was N135 that the primers were "Federal Magnums". The bullets looked like 124 gr Lapua S374 (.308") due to distinctive crimping grooves. I didn't ask what charge he used as shaking the cartridges sounded like there was reasonable amount of powder. When I filled the magazine with them he suddenly gave me three more rounds. I put them into magazine too and started shooting.

The first three rounds went fine and ejection was similar to my own loads. Then, the slam fire took place. I sqeezed the trigger for fourth round which also discharged the fifth blowing some pressure right against my face.


Here's the rifle right after the incident, field stripped for inital inspection.




Here's what I've found so far.

Bent receiver rear. It's not the receiver cover as if you use another cover the crooked gap remains. There was no gap before this crap.




Shiny imprints and trigger guard latch plunger rupture caused by the bolt and its carrier slamming right backwards.




Damages on the bolt rear after contacting the trigger guard latch plunger.






In this picture the bolt face is slightly cleaned from soot but after the incident I couldn't find any signs of dirt that could have hindered the firing pin movement. The spring snapped it back when you stop pressing the rear. The pin keeps remaining straight and flawless.




Some steel chip, either from the receiver bottom or recoil lugs.




Here's the brass. The left one is one of those that was fired normally and right one is supposedly the fifth round discharged out of battery. You can see the primer has intruded the firing pin channel rather aggressively. Could it be the primer wasn't seated fully home and the bolt face ignited it? I guess the tip of the firing pin and the pin channel could leave that kind of imprint even though the pin never striked? On the other hand this is one of the cartriges that I "inspected" before loading the magazine. Errare humanum est, I suppose.





 

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I do not believe it was an out of battery firing. The damage to the rifle would have been much more severe and the case would have blown apart.
The fired case was fully in the chamber when fired.
What was your load? What weight bullet?
 

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Wasn't out of battery first. The brass case would have been blown apart along with your magazine and wood stock.

Lesson here is to NEVER shoot anybody elses reloads. The 4th round was short on powder, which ended up in the 5th round instead with severe overcharge. Fourth round short stroked the action which didn't reset the hammer, only pulling it back, then the action wend forward fed the overcharged 5th into the chamber and the hammer that followed forward set it off.
 

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Wasn't out of battery first. The brass case would have been blown apart along with your magazine and wood stock.

Lesson here is to NEVER shoot anybody elses reloads. The 4th round was short on powder, which ended up in the 5th round instead with severe overcharge. Fourth round short stroked the action which didn't reset the hammer, only pulling it back, then the action wend forward fed the overcharged 5th into the chamber and the hammer that followed forward set it off.
Primer pockets in S&B 7.62X54R brass are shallower than in other brass. I always advise people if they shoot S&B 54R ammo, commercial or reloaded, to back off firing pin protrusion (M91/30 and Finn's.) S&B brass is too stiff for reloading, and should be annealed before reloading.
 

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That 5th round was way HOT!!! Cratered the primer, and flung the bolt and carrier back so hard it made the imprints in the parts you see and bent the back of your receiver.

NEVER EVER USE SOMEONE ELSES RELOADS!!! I don't give a care if he is your best friend, just don't do it! Your rifle may still be safe to fire, but I'm not a big expert on SVT's can't afford one.
 

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That 5th round was way HOT!!! Cratered the primer, and flung the bolt and carrier back so hard it made the imprints in the parts you see and bent the back of your receiver.

NEVER EVER USE SOMEONE ELSES RELOADS!!! I don't give a care if he is your best friend, just don't do it! Your rifle may still be safe to fire, but I'm not a big expert on SVT's can't afford one.
Check headspace. If within spec I concur with Joe7170. I don't have a SVT, but I do shoot and reload for a Swedish Ljungman AG42b, which copied the SVT bolt and carrier. BTW Eklund made several design improvements with the Ljungman. One of these is a clever telescoping recoil spring guide that makes removal and reassembly of the bolt cover and assembly fast and easy. The other is the combination safety and bolt stop. In the event this is damaged or distorted, like the OP's receiver back end, it can be simply replaced since it is a removeable assembly. If a later version of the Tokarev would have picked up on these improvements, the rifle might have had a longer service life.

Regarding reloading for any self-loader, hard milspec primers, e.g. CCI No. 34, are the only ones to use. I weigh every powder charge, and I inspect primers to make sure they are seated below flush with the rim.
 

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Discussion Starter · #13 · (Edited)
I doubt any overload could bend the receiver rear like that as in that case the damages should be in the bolt & receiver lugs. Remember, being gas operated firearm the bolt and its carrier are pushed back by the gas piston rod, NOT by recoil!! The piston simply does not yield enough gas pressure to hit the moving parts as violently as this.

The gun burst-fired the fourth and fifth round which is not how factory matching 1941 SVT-40 should operate.
 

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IF the SVD-40's piston and cup are worn ( most are) the gas selector has to be opened more than normal. Add a really hot load and you can start to move the case while it is still under pressure. The primer will start to move as soon as the bolt unlocks allowing for any play at the bolt head to be taken up. In worse cases,the base of the case will be ripped off leaving most of the case in the chamber.
 

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Discussion Starter · #15 · (Edited)
If properly in battery the bolt cannot unlock until pushed back by the gas piston rod. The pressure coming via the piston port starts to increase when the bullet has passed the port. If the piston parts are worn some pressure is lost and the gun doesn't necessarily cycle. I got the position 1.5mm which was barely enough to pull the brass out.

If only the fifth round was hot why the gun swithced into full auto during the fourth shot? I got all five cases here and only one has the firing pin mark gone strange. Still the primer exterior is more round than on the others which is not sign of high pressure. In my opinion the primer center could get cratered if the hammer didn't stike and there was no hammer & firing pin pressing the primer and the primer was free to intrude into the firing pin channel.
 

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Discussion Starter · #16 ·
Wasn't out of battery first. The brass case would have been blown apart along with your magazine and wood stock.

Lesson here is to NEVER shoot anybody elses reloads. The 4th round was short on powder, which ended up in the 5th round instead with severe overcharge. Fourth round short stroked the action which didn't reset the hammer, only pulling it back, then the action wend forward fed the overcharged 5th into the chamber and the hammer that followed forward set it off.
The SVT hammer gets reset when the bolt carrier is opened about 2". Way more is needed to eject old brass and feed another round.

A very common scenario with SVT is that spent case goes back into chamber without ejection and the hammer gets ready to fire.
 

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From the description of the event and the appearance of the cases, I suspect this is a mechanical problem with the rifle and the use of somebody else's ammunition was an unfortunate coincidence. There isn't any way that I can image a loading of the 4th round (underweight or overweight) can cause the fifth round to fire. A close inspection of the trigger group, focusing on the interrupter is where I would begin.

Even though it this incident seems not to be related to reloaded ammunition, the point made by others about using random reloads are valid. More than a few times I have been at the range and people have been shooting what they call "hot" loads. When I get home I look them up and they are far above the maximum; far enough that "stupid" is a better term than "hot".
 

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CH: Historically, early SVT (38's I guess) had issues with the cycling of normal ammunition battering the rear of the receiver to the point of causing cracks. This is mentioned in the Chumak book. I think it's possible an overpressure round could drive the bolt and carrier back hard enough to do this damage. I also wonder if the damage you point to on the rear of the bolt could have been done while in battery and locked against the hardened insert? Are there any signs of additional damage in any other places? With regard to the double fire, I had a rifle that would occasionally do this on the 4th round, usually when I was using heavy bullet ammo ( and usually after the first 3 shots were starting an excellent group!). The same rifle never did that with light ball surplus so I attributed it to some vagary of the trigger mechanism.

Ruprecht
 

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...

If only the fifth round was hot why the gun swithced into full auto during the fourth shot? I got all five cases here and only one has the firing pin mark gone strange. Still the primer exterior is more round than on the others which is not sign of high pressure. In my opinion the primer center could get cratered if the hammer didn't stike and there was no hammer & firing pin pressing the primer and the primer was free to intrude into the firing pin channel.
The fourth shot cycled the rifle normally, and the fifth shot was the slam fire. Fortunately for your health, and your SVT, the slam fire occurred with the round chambered, or nearly so. A slam fire that occurs out of battery, with a part of the cartridge case outside the chamber is the one that destroys the rifle and injures, or kills, the shooter.

Your pictures show primers that are flush with the cartridge head. As I mentioned, 7.62X54R primers should be well below the surface of the cartridge head. A high primer that fired normally would reseat itself during case setback. Your photo of the 5th case shows the primer bulging, and since it entered the face of the bolt, indented itself on the tip of the retracted firing pin. This is the result of extreme high pressure, due either to an incorrectly loaded round, or a partially chambered case. In the second scenario - partial chambering - the pressure follows the line of least resistance.

The damage to the receiver was also likely the result from an out of battery slam fire. The rifle fired and cycled before the bolt's lugs engaged, so there was much less resistance to the operating rod's thrust, since some of its energy is normally expended in camming the bolt out of its slot as the bolt carrier begins its rearward travel.
 
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