SVT question

emmab

emmab

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Hi I was using my SVT and have noticed that I couldn't get consistent ejection(I know) without my gas cylinder on the maximum setting of 7. I looked at the parts involved and couldn't really see anything wrong with the pieces. The holes in the cylinder seem fine as well as the tube out.The parts fit together well when in place. I'm wondering what is involved to lower the gas setting in case seven stops working. (Short of fiddling with the hole sizes)
Cheers
 
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With the gas regulator removed you can check the gas port (in the barrel) for blockage by inserting a small drill bit through the hole on top of the gas block. This would also reveal the presence (highly unlikely) of a misaligned key (the thing that holds the muzzle brake assembly in place). Have you checked the bolt/ carrier for any sign of resistance (remove the recoil springs first)? Do you lubricate the sliding parts with anything? Does the cylinder slide easily on the piston without being too loose? Is the chamber reasonably clean? All I can think of but, frankly, if it's cycling well at 1.7 I wouldn't worry too much about it. Try different ammunition and lube approaches. Also, have you tried simply cycling a few rounds through it by hand to verify proper ejection (at the range with muzzle pointed downrange, of course).
 
What kind of ammo are you using? Try using regular milsurp ammo. Russian or Czech made.
I had similar problem with my SVT when I just got it. Rifle was taken care of, clean and oiled when I received it but it wouldn't eject properly unless on 1.5 or 1.7. Tried 2 or 3 different kinds of ammo, didn't help. I posted here and was told to take the thing apart and clean the hell out of it. Somebody suggested using soft brush with cordless drill and giving it a spin for about 15 seconds, especially around chamber area. Whatever it was that caused cycling issues went away after cleaning. Rifle works fine on 1.2 or 1.3 now.
 
Thanks. I'll try all the suggestions. I'm leaning toward a bad fit between the tube out of the cylinder and the cup that holds the op-rod piston. Not sure though.
Cheers and thanks for the replies
 
When you have her apart, take the piston and put it in the tube, is there any noticeable slack, especially from side to side? If there is, its bypassing gas and you need a new piston and tube set. You should buy a spare set anyway, just to have it, if your planning on keeping the rifle.
 
Right. I'll look into corwinarms. I remember they had a stainless replacement set up. The tube is in tight. There is some play around the raised area of the tube and piston. I'm using the copper washed Ammo , some with/ without the silver tip. Not sure if it's Czech or Russian. Not on clips. Wrapped in paper and string. And I've cleaned it quite thoroughly.
Cheers
 
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Cup and spigut is usually the problem if the ammo is not. Keep in mind though that these guns were designed using steel ammo and not brass. I know most indoor ranges use S&B or PPU, these guns absolutely hate that stuff. If Corwin's is sold out of the cup and spiguts I would try running milsurp rounds or MFS rounds. I have had the same problem with all of my SVT 40's and remidied the cycling issue with changing ammo alone. Also make sure the flutes are all cleaned out as well. The rounds are designed to float in the chamber also using gas pressure to aid in the ejection. That's part of the brass problem. Usually the casing bloats out in the chamber and sticks in the chamber wall.
 
There was a posting some while back about a fellow who had a chunk carved out his chamber wall that was raising a ridge on each case during extraction. As I recall, he was also in the "I have to set it to 1.7 for it to work." situation, and I remember thinking that "If that's what takes 1.7, I shouldn't ever have to use that setting."
 
What ammo are you using?

I have had good results with Chinese Surplus in my Tula, I have also had reasonable accuracy with MFS 203gr SP. My Izvesk has yet to malfunction on me with a setting of 1.5, My Tula with irons has stove-piped (caught a spent casing in the action while it closes on ejection) with MFS 185gr FMJ. I didn't like the MFS FMJ because it seemed to be less accurate in the mosin's I used and both SVT's compared to its SP 203gr counterpart. With limited options available I will by only the MFS SP 203gr in future or nice surplus though I have too much of that already... Really I am crossing my fingers for semi affordable loaded brass to rear its head again... Someplace under $38-40 a box please
 
philhut said:
... My Izvesk has yet to malfunction on me with a setting of 1.5, My Tula with irons has stove-piped (caught a spent casing in the action while it closes on ejection) with MFS 185gr FMJ. I didn't like the MFS FMJ because it seemed to be less accurate in the mosin's I used and both SVT's compared to its SP 203gr counterpart...
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As I understand it, both the PPU and MFS versions of the 185grFMJ-BT are intended for target shooting and downloaded from the 182gr type D heavy ball (machinegun) ammo by around 100fps, so I'd expect a lower port pressure. Did you try your Tula at 1.7?

Regards,
Joel
 
Honestly I have never adjusted the gas setting on either of my shooter SVT's. The Tula was set at 1.5 when I got it and the Izhevsk 1.3. I just figured the previous person handing the rifle may have figured something out. Seems to work well. By stovepipes I am talking maybe 1 round out of say 30 or 40 on a particular day with MFS FMJ and my Tula. The Izhevsk runs everything like a beast even PRC. I am down to my last box or two of FMJ anyway so its no big deal tinkering for it, bought it for a song on EE so can't complain to much just wouldn't pay retail for it after using it.


per videos I have seen online to adjust gas setting simply use an adjustable wrench and adjust... bonus if you have a brass or soft mouthed adjustable wrench, I do not. Turn it in the direction of low to high or high to low, do not turn it from 1.7 directly to 1.1. Should be obvious but I work in an ER sometimes the obvious isn't so obvious.
 
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philhut said:
Honestly I have never adjusted the gas setting on either of my shooter SVT's. The Tula was set at 1.5 when I got it and the Izhevsk 1.3. I just figured the previous person handing the rifle may have figured something out. Seems to work well. By stovepipes I am talking maybe 1 round out of say 30 or 40 on a particular day with MFS FMJ and my Tula. The Izhevsk runs everything like a beast even PRC. I am down to my last box or two of FMJ anyway so its no big deal tinkering for it, bought it for a song on EE so can't complain to much just wouldn't pay retail for it after using it.

per videos I have seen online to adjust gas setting simply use an adjustable wrench and adjust... bonus if you have a brass or soft mouthed adjustable wrench, I do not. Turn it in the direction of low to high or high to low, do not turn it from 1.7 directly to 1.1. Should be obvious but I work in an ER sometimes the obvious isn't so obvious.
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I'll throw in a few things. First, you DON'T want to round off the pentagonal gas adjustment nut - use something of the correct fit. If you don't/can't buy an SVT tool (some of the replicas are quite good, some no to much; dunno about the evil-bay "originals") I've seen references to DIY fabricating the pentagonal wrenches with suitable jeweler's/needle files, from a flat bar drilled slightly smaller, from a small crescent wrench, and from a small box-end wrench.
Second, (as you may have already seen) you want the gas tube screwed down tight enough that it does not shoot loose and leak gas. This generally locks the gas regulator in place, so you usually need to loosen the piston before adjusting the gas setting. If you use some high-temperature grease or thread anti-sieze on the gas regulator and gas piston threads, it's quick and relatively easy to do with suitable tools (also facilitates disassembly for cleaning after lots of rounds fired). At the range and using a repro tool, I can lock the bolt open, pull the cleaning rod, slide the barrel band forward, remove the upper barrel shroud, back off the piston ~1/4 turn, adjust the gas setting, snug the piston tight, and reassemble, all in less than 45 seconds if no-one is distracting me.
Third, the gas regulator is perfectly circular in cross section other than the nut, so it really doesn't matter in which direction or how far you rotate it, just that you arrive at the desired setting and align the scribe marks before you tighten the piston down.
Last, Just because something is functioning reliably doesn't mean the action is not pounding excessively, especially without a buffer and/or a long bolt travel. Given the difference in port pressure with different loads, especially different bullet weights, and from summer to serious-winter temperatures, it is usually worthwhile to find the lowest reliable port setting for different loads and conditions to get reliability with minimized wear and tear.

Regards,
Joel
 
joelvca said:
I'll throw in a few things. First, you DON'T want to round off the pentagonal gas adjustment nut - use something of the correct fit. If you don't/can't buy an SVT tool (some of the replicas are quite good, some no to much; dunno about the evil-bay "originals") I've seen references to DIY fabricating the pentagonal wrenches with suitable jeweler's/needle files, from a flat bar drilled slightly smaller, from a small crescent wrench, and from a small box-end wrench.
Second, (as you may have already seen) you want the gas tube screwed down tight enough that it does not shoot loose and leak gas. This generally locks the gas regulator in place, so you usually need to loosen the piston before adjusting the gas setting. If you use some high-temperature grease or thread anti-sieze on the gas regulator and gas piston threads, it's quick and relatively easy to do with suitable tools (also facilitates disassembly for cleaning after lots of rounds fired). At the range and using a repro tool, I can lock the bolt open, pull the cleaning rod, slide the barrel band forward, remove the upper barrel shroud, back off the piston ~1/4 turn, adjust the gas setting, snug the piston tight, and reassemble, all in less than 45 seconds if no-one is distracting me.
Third, the gas regulator is perfectly circular in cross section other than the nut, so it really doesn't matter in which direction or how far you rotate it, just that you arrive at the desired setting and align the scribe marks before you tighten the piston down.
Last, Just because something is functioning reliably doesn't mean the action is not pounding excessively, especially without a buffer and/or a long bolt travel. Given the difference in port pressure with different loads, especially different bullet weights, and from summer to serious-winter temperatures, it is usually worthwhile to find the lowest reliable port setting for different loads and conditions to get reliability with minimized wear and tear.

Regards,
Joel
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I couldnt agree more. You said it all
 
+1 on the DIY option.

IzgTqC6.jpg


Half an hour with the little files and a scrap piece of brass, and if I'd have been thinking clearly I'd have made it 1/2 the size. The other two slots are for the cleaning rod, the piston, and the muzzle brake cap. The knobs on the bottom are for the stock bolt, but they didn't work out very well.
 
Good job Rayleigh. I need to make one myself. I came close to buy the right tool a couple times but never did. Too pricey for what it is
 
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