SVT cycling issues- poor ammunition or rifle problem?

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Langcaser

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Hey guys-

https://www.youtube.com/watch?v=PVMmVMx32Ic

Video showcases and explains nature of the problem where I also hypothesize the reason for its occurrence.

Out in the bush, the gun would not cycle. Out of perhaps ~30 rounds fired, perhaps twice it cycled a fresh cartridge. Pre-shooting, the gun was thoroughly cleansed of cosmoline and residual oils/greases. I am not a gunsmith or any sort of Soviet rifle aficionado but from my strip and clean job, I surmise that the rifle was complete in mechanical order and function.

I believe that expanding shell casings are resulting in my SVTs inability to cycle fresh rounds. Judging from what I've shown in the video and said here, do you believe this is a problem with the rifle or ####ty ammo?

Notes:

-Gas tube was cleaned, with little change in original problem paired with changes made to gas setting on muzzle.
-The surplus ammo in question is 60s Yugo surplus ammo of correct size for the gun.
-This ammunition was fired without problem in the 100s of rounds from a mosin during the same session
-We noticed the odd spent cartridge was split down the side. Although I've not verified this, I attributed this to aging ammunition and was unperturbed.

Unfortunately I will not have the ability for further testing at this time. I will not have to opportunity to now acquire new (different make/manufacture/age) ammo to test the rifle again until several month from now. Is there reason to assume only the ammo is at fault, and rifle is fine? Should you suspect a faulty rifle, I will promptly exchange the rifle for another, save risk being stuck with a lemon SVT down the road with the window of opportunity for exchanging past.

Big thanks with hopes of a positive verdict!
 
Have you tried different gas settings? Also when adjusting settings the marks have to line up otherwise you are partially blocking your port. Mine had the same symptom.

Btw might not want to load live rounds and drop the bolt on them indoors....just my thought :)
 
The reason I can be positive this problem is not gas related is that the bolt is stuck in the forward position after a round is fired. If there was a problem with the gas setting, the bolt could still be cycled manually to eject the spent round just like that of any bolt action gun.
 
I had a similar issue.

SVT would not cycle MFS ammo and another SVT that would only cycle MFS ammo.

Issue is gas setting related (over gassed I bet).

Try the 1.1 setting and then move up from there.

Hope this helps.
 
I am unable to link to the video, however, if I understand what you are saying: The first round fires, but then the spent casing does not eject?
And the bolt is also stuck in the closed position until you use a lot of force to open it? Which should mean that the gas system is not cycling.
 
Double check that your chamber is spotless and clean. No dirt or imperfections upon inspection. If that's all good could chamber or headspace be out of spec??? Just brainstorming. Ammo could be causing over pressure scenario too , you said your mosin shot it fine but was it hard to extract, hard pull on the bolt?
 
First off I am sure you removed the firing pin from that SVT-40 because otherwise you would have a major safety issue, particularly dropping the bolt like that on a live round. As a side note try to always feed from the magazine unless its something that is a single shot, as doing that can lead to either accidental discharge (do that with pretty much any surplus semi-auto and watch it fire) or damaging the extractor as they are usually designed for magazine feed.

Secondly, is the ammo lacquered? Personally I had some massive issues getting my SVT-40 to function properly, it didn't like several different types of surplus. It did like the MFS and also Russian surplus ammo. I would recommend playing around with the gas setting a bit to see if that makes any difference. Also try giving the chamber a good scrubbing with something like Hobbes and a 12gauge bore brush.
 
Yes, Firing pin was out for cleaning. To the above responses, it seems to me that in varying word choice you all have more or less said the same thing- that the gas regulator arrangement needs to be adjusted in some way.

Pulling the gas system apart and looking at it very carefully just now, I have removed and cleaned the small regulator nut in which the variable sized (1.1-1.7) gas orifices are bored. It was fairly unremarkable, with insignificant amounts of carbon deposits- certainly not enough to cause any clogging of the system. I also threaded a piece of dental floss through the hole in the barrel in which the gas enters the system, again it seemed quite clear and clean. Moving back to the gas piston and cup, all components seem to seat nicely, nothing seems loose or overly flaccid as other people have described in their svt gas system woes.

Im leaning toward chalking this up to a previously uneducated attempt on my part to adjust the system out in the bush. Quite likely a mixture of a misaligned gas regulator with the gas escape hole in the barrel, perhaps a bit of clogging and most certainly some poor luck. Everything seems to suggest the rifle functions fine and its just getting the gas setting dialed in. Perhaps another example for those of us who fancy ourselves as highly mechanically inclined- its never the tool (gun) its the operator.

Any closing thoughts or suggestions on the matter? Ammo or adjustment wise?

Thanks for your thoughts- and surprisingly immediate useful replies!
 
Had the same thing happening with my new SVT. It would fire 1-2 rounds and than jam. I had to use bottom of my palm to hammer the bolt open. Switching to 1.7 fixed the problem. I was using Russian surplus ammo.
 
This issue can be caused by two different things in my experience.

1) Chamber flutes are not cleaned properly. Brush it aggressively with a brass brush and solvent.

2) Too low of a gas setting. Since the chamber is fluted, the cartridge expands into the chamber flutes and is deformed. Extraction with a round as powerful as the 7.62x54r can require significant force. However, usually there is enough force to partially extract it but not enough to eject it, which causes the bolt to ram home and jam the expanded and deformed brass back into the fluted chamber at an angle that isn't precisely lined up with the flutes causing it to stick. Turn up the gas setting. Make sure you loosen the piston before you adjust the gas setting and remember that sometimes when you tighten the piston back down the regulator can turn very slightly out of alignment and you might need to compensate for that.
 
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bp2626- I like it, makes sense. Today ill run a brass brush and ream er out good. As for the gas system.. That thing is just about sparkling. Having it all apart I understand the importance for complete matching on the markings.

To think that there were probably plenty of poor Russian bastards sitting in ditches in the rain trying to get these rifles to function with little springs and gas regulators flying off the rifle at all angles... geez
 
Langcaser said:
To think that there were probably plenty of poor Russian bastards sitting in ditches in the rain trying to get these rifles to function with little springs and gas regulators flying off the rifle at all angles... geez
Click to expand...

That's one of the reasons why so many of them were abandoned and ended up in German hands. Germans on the other hand loved the rifle.
 
Langcaser said:
bp2626- I like it, makes sense. Today ill run a brass brush and ream er out good. As for the gas system.. That thing is just about sparkling. Having it all apart I understand the importance for complete matching on the markings.

To think that there were probably plenty of poor Russian bastards sitting in ditches in the rain trying to get these rifles to function with little springs and gas regulators flying off the rifle at all angles... geez
Click to expand...

The German Army loved that rifle, it even produced manuals (in Deutsch, of course ;)) and ammo that was said to work better than the captured Soviet ammo they had available.

I'm thinking that your issue is a combination of dirty flutes in the chamber and having the gas system on too low a setting. It's a pain to see those tiny numbers (unless you have 20-20 vision) and as has been mentioned, the marks MUST line up or you're blocking part of the gas port. There is a tool (part of the issued kit) that is specially designed to adjust the gas regulator - a regular wrench won't work because the regulator is shaped like a pentagon.
 
Corwin Arms has the gas adjustment tools as well as replacement stainless gas Pistons. If you end up with the gas setting cranked and still aren't getting a full cycle it could be your piston and cup seal are worn down bleeding off too much gases to function properly.

From your video I think your chamber just needs a good cleaning.
 
Langcaser said:
bp2626- I like it, makes sense. Today ill run a brass brush and ream er out good. As for the gas system.. That thing is just about sparkling. Having it all apart I understand the importance for complete matching on the markings.

To think that there were probably plenty of poor Russian bastards sitting in ditches in the rain trying to get these rifles to function with little springs and gas regulators flying off the rifle at all angles... geez
Click to expand...

When the chamber has been cleaned properly you should be able to see the marks the flutes leave on the extracted case around the neck and shoulder.
Mine cycles very nice with the gas regulator set at 1.2,the cases end about three feet away.

H.
 
For reference I find that fired brass will chamber with finger pressure in mine. I was actually going to try neck-sizing a couple of the fired ones, reloading them, and seeing if/how they work second time around.

It'll be the last ones I try that day, given that it may require the 1/4" brass rod to get them out.
 
Langcaser said:
To think that there were probably plenty of poor Russian bastards sitting in ditches in the rain trying to get these rifles to function with little springs and gas regulators flying off the rifle at all angles... geez
Click to expand...

I am rarely able to have a smooth shooting session with my SVT-40, half the time it is my incompetence and the other half it is the gun's
relative fussyness. I would be one who would have ditched this rifle in battle conditions. I love it for the challenge!
 
My SVT-40 does the same thing as yours in the video and I have largely fixed it.

I cleaned the hell out of the chamber using a wire brush, steel wool and finished up with a bit of sandpaper. This helped with extraction, but didn't solve my issue. I had to put my gas setting up very high. I'm worried that I will rip apart the extractor on my SVT-40 as it requires a lot of force to extract, but so far so good.
 
bp2626 said:
This issue can be caused by two different things in my experience.

1) Chamber flutes are not cleaned properly. Brush it aggressively with a brass brush and solvent.

2) Too low of a gas setting. Since the chamber is fluted, the cartridge expands into the chamber flutes and is deformed. Extraction with a round as powerful as the 7.62x54r can require significant force. However, usually there is enough force to partially extract it but not enough to eject it, which causes the bolt to ram home and jam the expanded and deformed brass back into the fluted chamber at an angle that isn't precisely lined up with the flutes causing it to stick. Turn up the gas setting. Make sure you loosen the piston before you adjust the gas setting and remember that sometimes when you tighten the piston back down the regulator can turn very slightly out of alignment and you might need to compensate for that.
Click to expand...

My SVT did this exact same thing when I first got it. Gave the chamber a good cleaning and turned up the gas setting to the lowest setting that would allow the rifle to cycle reliably, and no problems since. Unless I change to a significantly different ammo, in which case I might have to change the gas setting again. On advice of an SVT article I found once, when I'm trying new ammo in the SVT I bring a small deadblow mallet in case I need to "encourage" the bolt to open, much nicer than beating up on the heel of your hand or finding a chunk of wood...
 
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