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Thread: SVT-40 problems

  1. #1
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    Default SVT-40 problems

    Hello,

    I apologize in advance if there are already posts that deal with this set of issues. I tried the search feature and could not figure out if there were SVT operation problems already covered in the past...

    Took my new to me 1943 Tula SVT-40 to the range today for a trial run at 100 yards from a bench. Loaded Soviet 1986 Frunze/60 LPS light ball ammo that has given me zero problems with my Mosins into the magazine.

    I pulled back the bolt carrier handle and let it go forward, sighted in with a 6 o'clock hold on a paper target, and pulled the trigger. Nothing happened. I waited for 30 seconds in case it was a hang fire, then extracted the cartridge. The firing pin strike was just a bit off center, but not too bad. The primer itself had been knocked into the primer pocket, about what like one would see if a Mosin-Nagant rifle had not had its firing pin protrusion set properly. I reloaded, and the second round fired. I then had the third round jam going into the chamber, where the bolt could not be closed with a tap of the heel of the hand on the bolt handle, and it could not be opened. I got out a block of wood, and tapped on the bolt handle until it ejected the round. That may be a dirty chamber issue of some kind, and so I'll have to get into the chamber flutes.

    I attempted to fire the remaining rounds in the magazine, and I had a total of four rounds detonate and eject from the rifle, and a total of four where the cartridge would not detonate, and the primer appeared crushed. I decided the rifle was not safe to shoot, unloaded it, put the ammo away, and then cleaned the rifle with Hoppe's #9. I drove to a gunstore where there is a gunsmith I know, and he allowed me to take it apart there, and also detail stripped the bolt.

    The firing pin appears like new, intact, and it protrudes a good ways out of the bolt face when struck. The hammer appears to fly forward and strike the rear of the bolt with a lot of force.
    I was wondering:
    A) How ammunition sensitive is the SVT Tokarev design?
    B) Is it possible for the bolt when locked to depress the disconnector, allowing the hammer to fly forward when the trigger is pulled, but because the receiver shelf that the bolt locks down into from the camming motion of the bolt carrier is a separate piece in the receiver in order to adjust for headspace, can the trigger operate the hammer while the bolt is locked, but not fully in battery? Does this make any sense?
    C) Is this actually a headspace issue of some kind? What is the remedy for this kind of issue with a Tokarev rifle?
    D) The rifle is a refurbished STI import with reblued parts and so on. Everything is electropencilled/ forced matched. The trigger group assembly is all Kovrov parts, but just about everything else is Tula.

    I enjoyed shooting the rifle during the few times that it went "bang." About as loud as I thought it would be from the muzzle-brake, and relatively milder recoil from the self-loading mechanism.

  2. #2
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    Are you sure the bolt is completely forward and in battery.On the rounds that did not fire?
    Did you tap it with your hand each time before firring? Of course not that you should have to.But if having a problem like that i would do that on each round to make sure shes locked.Hows the gas system condition? What setting is it running on.Is it completely clean and very well lubed? And the flutes are spot less? The chamber is smooth and no marks from broken shells being removed in the past? And if so emery cloth and polish it up !

  3. #3
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    Hi, my friend and future owner of at least 3 SVTs!

    First, Soldier, you get 3 latrine-cleaning duties for not being sure that you chamber was squeaky clean. Never take a weapon to the range unless YOU cleaned it and checked YOURSELF.
    Now that I am done being a patronizing a-hole, this is what needs to happen:
    Take the rifle apart and completely disassemble your bolt, and I mean completely, including the fire pin and the ejector. Try not to loose the small spring and plunger hiding behind the ejector. I am 99% certain that your fire pin, spring and the channel are bathed in cozmoline, or worse, caked in soviet grease. Clean the ejector nest and parts as well, it will save you some future issues.
    Soak and brush the chamber until you turn blue in the face.
    Other troubled areas are:
    Gas system has to be thoroughly cleaned. There is no excuse for not doing so. Make 100% sure that your gas plunger setting is lined up perfectly to the hairline on the gas chamber.
    Trigger system parts need to be free of cozmoline and lightly lubed.
    Bolt rails on the bolt carrier and receiver - the same no cozmo, light lube
    Edit: Also the bolt return spring and guides have to be cleaned.
    Edit2: Check that the locking nests that the bolt lugs drop into are clean, they are immediately behind the magwell and to the left and right of the mag-hold-open. The dirt there would cause incomplete locking and could case bad extraction.
    Last edited by serzant; 11-26-2010 at 04:23 PM.

  4. #4
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    I have had a couple rounds do the same thing in Mosin Nagant rifles. 1 silver tip Czech and 1 copper washed. I retried the same rounds in several rifles and no fire. It can be ammo quality.

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    Serzant what do you attribute your recommendations to in cleaning the weapon down to bare metal? Many of the steps you recommend don't have anything to do with his issue which sounds very much like an ammunition problem.
    I do agree with you in that the bore and bolt should be cleaned prior to firing and left free of lube. The bolt guides and op mechanism should be lightly lubed. Gas system should be completely free of any oil or lubrication of any kind. Several types would suffix on areas that need lubrication and even many quality dry lubes exist.

    I would obtain a 20 rd package of several types of ammunition and try those. The yellow tipped Bulgarian shoots particularly well as does the 150gr Yugoslav brass cased types. I would dry several other types to rule out an ammunition problem first.
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    Have to agree about the ammo. Some of the 80's dated Russian LPS can give fits in Maxim MG's and yet work perfectly in rifles with greater firing pin energy, like the 91/30. If the firing pin is delivering enough energy to seat the primer deeper into it's recess, it should be sufficient to fire the cartridge. As primers start to loose their sensitivity, this is one of the signs. That is, light blows in some weapons that have a marginal problem, say a weak hammer spring. As Vic suggests, try some different manufactures/dates before changing anything. Gas adjustment will probably cure the cycling/feeding issues but it is sometimes necessary to tweak the magazine feed lips. Lower settings of 1.3 or so are good starting points. Higher settings can cause the rifle to cycle to fast before the magazine spring can raise the next cartridge into position, causing a mis feed. Also be sure your extractor spring is up to snuff. These are great rifles and a lot more reliable than some believe. Good shooting. JH

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    Sorry I've spoken before you did, Vic and other "senior" members!
    I eliminated ammo as the issue, because in 16 years of collecting soviet weapons I had zero FTFs with Russian-made ammo (and I had issues with some other commy block ammo). I never owned a Maxim, though so it is possible.
    Also, there is a troubleshooting guide in the SVT-40 manual on Page 81 that states that fire pin channel must be free of dirt an slightly lubed. And bottom of Page 83 explains about the receiver.

    The OP asked a specific question about locking, which deserves a response as it is often overlooked by the experts. The locking lugs are depressed in the recesses in the receiver behind the mag well. If they are prevented from being fully depressed by dirt, the bolt may close incompletely, but the firing pin will strike off center, as the OP indicated and the retraction of the bolt will be hindered by excessive friction between the lugs and bolt carrier.
    Here is the Bolt in its fwd position, lugs in the recesses


    Here is the view of recesses

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    I can only speak for my self of course serzant, but all opinions are welcomed here. I only mentioned the 80's Russian LPS because it has been well documented as giving uneven primer performance since it first appeared on the surplus market in the mid 1990's. Few rifles have the combined weight of the mosin 91/30 firing pin/cocking piece/and spring which will set off almost anything! Some MG's do indeed have great striking force but some, like the 1910 maxim, rely on firing pin spring strength alone. They are the "canaries in the coal mine" if you will, when it comes to "dying" primers. That said, the off center strike is quite normal (the front of the bolt is captive and even if the rear is elevated, the firing pin imprint is changed little.) Also, the SVT has a generous relive cut under the bolt to capture debris. I have found primer cups from fired cartridges smashed under the recess and the rifle still fired perfectly. Because the hammer tension is all that keeps the firing pin forward as the cartridge is firing, the rifle is susceptible to primer "pop outs" which can indeed block the firing pin channel. As you say, cleaning and inspection BEFORE shooting is a good idea. And of course, the safety sear prevents the hammer from dropping until the bolt is fully in battery should dirt build up under the locking surface become an issue. Very nice pictures. JH
    Last edited by haak48; 11-29-2010 at 08:17 PM.

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    Default Spacibo/ Thanks!

    Thanks folks.

    The rifle was detail stripped by me when I got it. I cleaned it about as good as I do most of my surplus firearms, which may be a bit excessive. I did run pipe-cleaners into the gas port in the barrel and the fixed gas piston. I cleaned the valve/gas tube attached to the operating rod, and the operating rod. I did leave the op rod clean and dry, as well as the op-rod return spring.

    The gas setting was on 1,3mm. I did have some Polish LPS silver-tip 147gr. 1975 ammo, which I probably should have tried to eliminate that possibility. I also had some brass cased 182gr. Yugoslav heavy-ball with brass cases (1986 date, like the ex-Soviet ammo I used). Honestly, shooting 7.62x54r ammo from various countries in my Mosin-Nagant rifles, the only time something like this happened was when I failed to properly gauge the firing pin protrusion. That is what this issue put me in mind of. I can post pictures of the cartridge cases, if folks think that will be helpful. I did notice that the firing pin left a faint dimple on unfired cases that had been chambered, much like my Garand. Fired cases were normal. Unfired cases had the Berdan primer crashed in, with a small dimple, but that was not sufficient to detonate the cartridge.

    I've got the rifle all apart again, soaking in Hoppe's #9. I will say, on reading your replies, that I might have used the wrong lube. As a Garand guy, I usually use a Lubriplate grease on sliding parts, and this rifle was no exception. Maybe the Lubriplate acted like cosmoline preservative grease? On the Garand design, if the locking lugs of the bolt are not fully turned into engagement, the hammer cams the bolt all the way shut. With the SVT-40 and the SKS, is it the case that the rifle could have a case chambered, appear to be in battery, but when the hammer drops, it fails to fire because the bolt is not cammed all the way down into the receiver recess? Another SVT person I have talked to wondered about the hammer spring. But when I put the bolt and bolt carrier into the locking position, the hammer falls quite sharply and evenly.

    Serzant: trust me my friend, I really did clean and lube the rifle when I got it... Perhaps I did use the wrong kinds or techniques for lubricating it however. I have a cyrillic/ Russian SVT-40 manual, but I do not speak Russian. I have been using a combination of the U.S. 1954 training circular, the Smith and Smith _Book of Rifles_ and the 1965 International Armament Co. books to help me out with it. The lines on the tiny gas nut and the gas cylinder port appeared matched up, and when I detail stripped the bolt [admittedly, something I did not do before I took it to the range], it was clean and the channel was not blocked.

    Führer: Are there any tips or tricks for getting down into the chamber flutes? I let it sit a day or two with Hoppe's #9 and then dry patched it out... Should I be thinking of dental picks or something like that to get into the grooves? I don't think I have anything like a chamber mirror or something like that to see if a case ruptured in the chamber or something like that. Now that I think of it, I guess I should get a 7.62x54r ruptured case extractor while I'm at it.

    Thanks for the replies thus far. It has me mystified.

  11. #11
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    One more thing I should have mentioned: did you gage the fire pin?
    I use Mosin screw driver tool which has Go/NoGo gage on the side. Just in case...


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    Your primer strikes sounds "normal" on the mis-fired cartridges. If the pin is pushing the cup into contact with the case anvil, that should be sufficient to fire the cartridge. Of course the fired cartridge will look different because the cup will flow back against the bolt face and give the appearance of a deeper impression. It still sounds a lot like primer insensitivity. Please let us know how it works out. JH

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    Dave,

    I, like you, use a Lubriplate grease on my SVT and every other semi auto and bolt action I own. That should not be contributing to your problem in any way. I am very sparse in its application though, just a very, very light film...maybe you are using too much...?

    Make sure you load your magazines with the rim of each cartridge immediately in front of the one below. That will contribute to a feed issue.

    SVTs can be a bit quirky. My Finn will not chamber a soft point ammo, as the feed angle is too steep and the nose winds up catching and stopping the cycle. I must use FMJ, but considering the rifle was never designed to cycle anything but, its no big deal to me.

    Keith

  14. #14
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    If your hammer is releasing when you pull the trigger, then I had the exact same problem when I got my first SVT40 many years ago. My problem turned out to be a weak hammer spring. The hammer just didn't have enough force to ignite the primer each time. It fired about 1 out of 4 times. The rifle had probably been stored cocked for 50 years. A replacement spring solved the problem.

    Cass

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    Default Spacibo/ Thanks!

    Thanks Cass. I just might have to try that out. I'll try to get a replacement hammer spring from Numrich or some outfit like that and see if that helps. I just might try to run down to the range on Sunday and see if I have the same issues with other kinds of ammo.

    I'll get it solved soon I hope.

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    Excellent we look forward to your return report.
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    Well, this was a quicker return from the range than I intended...

    I cleaned the rifle, especially the bore and the chamber and the receiver where the bolt locks down. I cannibalized an old cheap cleaning kit for two sections of brass rod and a .40 cal. and 20-gauge brush to scrub the chamber. I went a bit easier on the lube than I might for, say, one of my M1 Garands... I reassembled everything, double-checked it, set the gas nut at 1,3mm and took it to the range.

    The Good News [Polish ammo works without buying a new hammer spring!]:
    I fired four rounds of Polish 1975 LPS 147gr. copper-washed steel cased ammo.
    The Bad News: [Rifle chamber behaves like an ornery Mosin-Nagant!]:
    Each stuck in the chamber, requiring forceful racking of the bolt handle to eject the case. I stopped after round #3, took out the magazine, disassembled the gas system, and re-set the gas port aperture to 1,5mm. The fourth round also stuck in the chamber, and when I went to extract it, the extractor tore off the rim of the Polski case leaving it in the chamber. So I packed up and am now re-cleaning the rifle again.
    Observation:
    I guess the Mosin is more my rifle...I can figure out that one! Heh. Kidding aside, it seems like I've got quite a learning curve on this here SVT.

    The good news is that the rifle appears accurate. I had two holes touching at 100 yards, a third that opened things up to about 3 1/2 to 4-inches, and then a fourth round that was a real flier [about 5 inches or so for the total four shots... But I was probably letting the sticky chamber get to me, and it was very windy at the range.] Could anyone direct me to how to go about getting into those flutes or splines inside the chamber area? I guess I'll see if "youtube" has any insights on the chamber.

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    If you put a round in the chamber by hand how does it feel pulling it in and out.It should have some play to rocking it up and down.I think that rifle may have a gas seal problem at the piston and cylinder.You know even with like new parts some of these guns just like to run at a higher setting.I have a nice Finn capture svt.It has a nice bore not mint but nice for a svt.And that rifle with like new gas parts(the originals) I also have the new stainless piston and cylinder which i put in it and left them in there.I felt those would be best to clean and use at the range.It runs like a swiss watch on 1.7 and thats it.And it does not seem to be over working anything either.In other words the rifle is not getting beat up at all.Some just seem to like higher settings than others is my take.I don't know if it has to do with stronger recoil springs or what.It did have strong recoil springs and i put new ones in anyway.

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    Sounds like you need to turn the gas setting up.

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    Thanks Führer and MuscleGarunt. I'll do that. I will try the 1,7mm setting for a bit and see if I can go back down to 1,5mm. I'll also be sure to bring any and all equipment I might need to unstick cases. I was chagrined that I did not bring my one piece cleaning rod with me to the range to get the stuck case out. Third time is the trick! [I hope...]

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    I have a 1941 Tula that runs on 1,3 setting just fine and my 1941 Izzy runs better on 1,7.

    If we are getting into the gas queston, have you made sure that the key that holds the front end to the barrel is well centered (looking from the top)??
    That key passes right through the gas port and has an oversized hole in the center, but if it is incerted too far to one side, it will partially block the gas port.
    - Что это там за шаги на лестнице?
    - Да это нас арестовывать идут.

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    Hello serzant:

    Thanks/spacibo. I actually went and checked in the gunroom, where it is sitting being re-cleaned again. The key holding the non-rifled portion of the barrel, two-baffle muzzle-brake, bayonet lug and front sight onto the rifled portion of the barrel appears to be slightly more jutted out to the left than it is on the right. It is fairly close to being centered, but maybe just a bit more sticks out on the left-hand side.

    None of the diagrams or manuals I have mention messing around with that part... Is that something for a gunsmith to handle?

    The good news is that Polish ammo works! I'm almost out of the Soviet 60/86 anyway, so I'll reserve it for my Mosins I guess. I've been using an expensive foaming bore cleaner on it hoping that may get into the splines/flutes on the chamber better than I've been able to. I'll return to the cannibalized .40 and 20-gauge brushes soon too. I'll look around and maybe my muzzleloader has an old .50 cal brush I could use on the SVT chamber.

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    In all years of collecting these I only removed/reinstalled the front end once, so maybe that's why no-one discusses it. But the hole on the key is about 2 mm - 2.5 mm max diameter (to the best of my recollection). So yours only has to be off by 1mm to cause partial blockage. The reason it is not mentioned in the user-level manuals is because the riflemen were not expected to mess wit this part - every time the front end is removed, the rifle should be sighted in again. Penetraiting oil soak is recommended prior to attempting to move the key, as there is sure to be build up of carbon in there. If its less than 1mm difference, you probably should not bother. 1mm = 0.04"
    - Что это там за шаги на лестнице?
    - Да это нас арестовывать идут.

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    I think some people includeing me from reading on the boards.Get into the it must run on 1.3 or 1.5 mode.I did and played around for a bit on the 1.5 setting.Than went to 1.7 and everything is perfect.I wish i new for sure why some run on lower settings than others? I could see if the barrel bore was shot out a reason.But when bores are nice and all and gas systems are like new it leaves one wondering?

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    As for moving the locking key, I don't think I've got the equipment to do that here. But I will take it someplace and get it measured. It is really tight, and it appears staked in at the point it is at, which is *almost* centered. But that may be it. When the pressurized can of foaming bore cleaner shoots into the bore, a tiny bit comes out the fixed gas piston, so I know some gas can get through there... But maybe it is only half what it should be.

    Führer: Yes, I think you are probably right. I am utterly new to the SVT. I only have experience with M1 Garands, M1 carbines, SKS rifles, and vicariously through some shooting buddies, Kalashnikovs and ARs. So when I read all the stuff that is available, it seems the Soviet manual called for a new rifle to be at 1,5mm, but an older piece could go lower: 1,3mm or 1,2mm. And then people who know that the rifle and its parts are in short supply Stateside [Lucky Canucks!], are leery about parts wear and breakage and so on, and so they advocate babying things as far as the gas system goes. Once I get the bore as clean as it possibly can get, I'll just make it a point to bring more gear with me to the range to tinker with it, and I'll start eliminating the variables one at a time until I get it right. I do thank you for helping a "newbie" with this stuff. Basically, at the end of the U.S. 1954 training circular it has remedies for such problems like: "broken firing pin, firing pin too short, rifle is dirty--clean rifle, extractor is dirty or broken--clean extractor or repair/replace extractor, and so on. When the problem doesn't come from that source it gets bewildering. I've still got other kinds of 7.62x54r ammo to try out too. For now I'll look into the gas-port locking key issue, reset the nut at 1,7mm and get a new hammer spring.

    Interestingly, perhaps, V.2 of the 1965 George B. Johnson and Hans Bert Lockhoven/ Interarmco book _International Amrament_ (Köln, 1965), p.174 says "A good gun, of sound design and competent workmanship, the Model 1940 [Tokarev self-loading rifle] had all the qualifications of a successful weapon--except for two shortcomings: poor ammunition and troublesome maintenance. ... With the rapid deterioration in ammunition which took place after the German invasion, other functioning difficulties mounted; and in the sub-arctic cold of winter fighting, when margins of reserve power of both ammunition and mechanism were at a minimum, operation became critical. These and other problems, such as the difficulty of adjusting the gas port or field stripping the gas system for maintenance without special tools, caused consideration of the Tokarev as a replacement for the bolt action rifle to be suspended. ..."

    I'm wondering if the chamber on mine is just a bit too roomy? I wonder if the hard Soviet primer is getting knocked into the pocket by the hammer because the cartridge can move forward just a bit, and the Polish cartridge case bulges a bit when it fires, but doesn't go back to shape quite the same way as brass cased ammo and "sticks" in the chamber? For now I'll start on your recommendations there. Thanks again, I'm much obliged. I just don't know anyone at work who owns guns, and my gun friends don't own Tokarevs... Quite a conundrum.
    Best,
    Dave

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    If your muzzle extension key is close to center don't mess with it. It is a press fit. if you move it around it could wear some material off the key. Then it won't stay put. I advise to not try to adjust the key. Try raising the gas setting. If you shoot 3 rounds and 2 eject but one gets stuck in the chamber you need to turn the gas up. reason this happens is, the case is extracted piping hot while it is still expanding. If the bolt doesn't get enough of a push to eject the case it jams the now swollen case back into the chamber and it gets stuck.

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    The key can be tapped with a standard screw driver-

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    I had stovepiping on my Tula SVT. Increased the port setting slowly and it works great on 1.7
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    Folks, I just wanted to let y'all know that I meticulously put the re-cleaned rifle back together with the gas port aperture set at 1,7mm and it it went through Yugoslav 1986-mfr. 182gr. and Polish 1975-mfr. 147gr. silver-tip LPS without any problems whatsoever. I had to move the rear sight up from 100m to 150m, and the sight windage will have to be adjusted because it is about 3 1/2 to 4 inches to the right of POA at 100 yards. Shooting at an 11x17-inch sheet of paper with a six-inch square bullseye and a ten-inch square around that, it put six rounds of Yugo into the six-inch square, two fliers in the 10-in. square, 1 just outside the 10-in. square, and the last off the paper, probably to the right. With the Polish LPS, I had three in the six-in. square, five in the ten inch square, and two off the paper, again, probably over to the right. Once I get the windage issue taken care of things should be just great!

    Thanks again to everyone for their advice and recommendations. Much obliged.

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    dave, if you are switching between light ball and heavyball, you might want to recheck the gas setting. if you're running fine at 1.7 with the light ball, try the heavy ball at 1.5 and see if that works.
    I like to use the fn-49 method for setting the gas system. single load one round, set the gas at the lowest setting, chamber and fire. if the round doesn't eject, single load another round, move the gas setting up one, and chamber and fire again. do this until the round ejects and the bolt locks back. Changing ammo to me means checking the settings like this again.

    my observation on these rifles compared to a garand is: you can remove the gas tube on a garand and clean the entire gas system, including the gas hole in the barrel. unless you are removing the muzzle extension on an svt, the same thing is not true. you can stick a paper clip or dental pick through the hole, but there's bound to be a little carbon buildup in there.

    on the piston/cup: check the end of the piston that doesn't screw in. the bevelled surface on this end gives you the primary seal for the extraction impulse. If this bevelled surface isn't smooth, it will leak gas around. this initial impulse is not only the primary extraction impulse, it lifts the bolt lugs up out of their recesses.
    after the initial gas impulse, the gas flows between the side of the piston and the walls of the cup as the cup travels to the rear. if the gap between the sides of the piston and cup is larger, it will require a higher setting to work. If the gap is smaller, it will require a smaller setting. This part of the cycle doesn't have to be as strong as the initial impulse, as it only has to move the bolt to the rear to accomplish ejection.
    Spring tension from the op rod spring and recoil springs will affect this also. any type of binding from the bolt carrier or the op rod (where it passes through the hole beneath the rear sight) won't help.


    That's my personal take on how the gas system works, not from a book but from looking at how the gas system goes together and a lot of thought.

    y'all have a good day, Keith
    Say you love her 'till she lays down the butcher knife. -Tim Wilson

    "Luck" is what happens when preparation meets opportunity

  31. #31
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    Thanks Keith. I'll try that out next time. I only had time to shoot at two targets and it was getting dark fast. I shot several five round strings after not having the rifle work as a self-loader on 1.3mm and 1.5mm settings, and on cleaning it, I noticed a lot of powder residue and carbon fouling on the exterior front of the gas regulator nut area, leading me to believe that the gas system may in fact be somewhat leaky like you describe. So I went "full blast" 1.7mm on this trip. I probably should try 1.5mm again with the heavy ball, and then go back up to 1.7mm with the LB. On this range trip, I shot both at 1.7.

    Ejected cases went out front and to the right about 15 to 20 feet, and recovered brass had a small side dent where it hit the receiver cover on the way out. Nothing seemed too excessive, however.

    Thanks for the appraisal. I'm just gratified it is working like it should.

  32. #32
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    Glad to hear you got it working; nothing more frustrating than a single shot semi automatic rifle. Well maybe a single shot M60 machinegun.
    Looking for Samco/CAI scopeless Yugo PU bolt KX5017

  33. #33
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    Glad its running OK too. It should run on 1.5 no problem with light ball and 1.3 on heavy. Just be sure gas ports are clean and lined up.
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