SVT40 Unusual Behavior - Multiple Firings

[jmmitc06]

Hey all,

So I've come to get some input on what could be causing the SVT-40 I recently acquired to occasionally fire multiple times on one trigger pull. In short, the first few mags worth of ammo shot fine, one trigger pull equaled one boom. Then about 4 mags in it would occasionally fire 2 rounds with one pull of the trigger. At this point the gun is very hot, smoke venting from the barrel shroud, but I doubt hot enough to cause cook off. I let it cool down for a few minutes but after one more mag it was doing it again.

This behavior is elicited using both commercial ammo (the only commercil ammo I had felt rather hotly loaded to me) and surplus ammo when the gun is hot.

Any ideas on what would cause this behavior? Currently thinking either I was unintentionally bump firing it from poor trigger follow through or the sear wasn't functioning properly. Of course I doubt the temperature of the gun could effect bump firing it, but the gun wasn't cold but for the first couple of mags so not enough data to say if that is a factor or not. Any hypotheses would be appreciated.

 

[peyton]

I do not know the cause but I would defnitely quit shooting it or else someone will "Rat you out" for having an automatic rifle without papers. What is the magazine capacity and are the magazines good to go?

 

[jlrhiner]

Clean the bolt-carrier group really well. Check the firing pin to see if it's bent. Make sure assembly is correct.

 

[Trooperdan]

I believe some SVT-40's were select fire.. wonder if you have some of those FA parts installed? Admittedly I don't know anything about the FA firing system or models.

 

[Double-O-Dave]

Your problem could be due to a number of problems. When you say it was "recently acquired", does that mean you got it used? If so, was it from a store, or a private sale/deal? If you got it from a store, whether new or used, I'd take it back to the store and ask for an immediate refund or exchange. If this was a private sale/deal, if possible, I'd contact the seller and ask them for a refund. If you aren't able to get a refund or exchange, I'd contact S&W Customer Service for help. They may be able and willing to assist you, but the return time could be lengthy. To me, it sounds like someone was trying to do a "trigger job" to it and goofed it up. Rather than do the right thing and get the piece fixed by a gunsmith, they passed the problem on to you. I completely agree with one of the previous posters (Peyton) - quit shooting the piece until you get it fixed. If my theory is correct, there's no telling what Bubba did to the piece, and I wouldn't shoot it until a gunsmith had gone through it and returned it to factory specifications.

Please let us know how this turns out.

Good luck,

Dave

PS: Sorry, I misread your post and was thinking SD-40, rather than SVT-40 (surplus Soviet military surplus rifle). My advice doesn't change much - except S&W Customer Service can't help you here. I'd go back to the seller and try to get a refund. Barring that, I'd get it to a gunsmith for review and repair.

Good luck,

Dave

 

[jmmitc06]

I did do a full breakdown last night and I'm pretty sure it had not been thoroughly cleaned since WW2. You need a PhD to disassemble it so I'm not surprised that it had not been done recently.

I did a quick cleaning on it before taking it out but during my full clean there was much gunk in the trigger group, around the sear and in the gas system. Looked like cosmoline or jellified/burned up gun oil and when heated gets really tacky, perhaps causing the sear not to engage. My hope is that this full clean will resolve the issue, as well as maybe not shooting nearly as much nearly as quickly.

Searching the interwebs this is not a uncommon problem with these rifles. I will get it checked out though before the next range trip so I don't get killed.

 

[tputto]

Since you're doing a full cleanup you may have done this already but check the firing pin channel and spring too, thats probably the origin of most random doubles. Mosinnagant.net has a subsection for SVT rifles with a lot of good info.

 

[LVSteve]

Only a double tap? Look up "Egyptian FN-49 with broken one piece firing pin" if you want to maximise your amusement.

Fingers crossed it is just crud in the trigger system.

Commercial ammo is probably heavy ball and may well be loaded with powder too slow for the gas system. I know the gas system is adjustable but proceed with caution. AFAIK the SVT was designed for light ball ammo ~148gr.

 

[jmmitc06]

Yeah, I checked the firing pin, it was a real pita to get it out but it appears to be working correctly.

Yes, most commercial loadings are heavier than the surplus stuff and I didn't shoot more than a mag nor plan on shooting it again in the rifle; had to do it to confirm it wasn't an ammunition issue.

 

[jmmitc06]

Just an update: After a complete clean of about 3 hours I took it back to the range and the same thing occurred on the second mag. It is now back at cabela's returned along with fears of black ATF helicopters coming to snatch me.

Thanks for the help and ideas.