As promised, here goes. Perhaps this could be made sticky for others?
Let me start with a little disclaimer, if you will. I love milsurps, and I love collecting them. I enjoy one that works flawlessly, even more so. These adjustments that I have made on several SVT-40’s have turned them from sometimes operational, to extremely reliable, on par with the SKS for FTF or FTE. These adjustments have allowed them to go from 3-5 MOA to 1-2 ish MOA iron sights. Keep in mind, I am not the world’s best shooter by far, and my eyes are not the best.
The key to increasing reliability and accuracy with these guns is in the gas system. That is where the biggest focus should be put, in my opinion. I have found that the guns become much more accurate, the lower the gas system is. So the obvious goal is to get it to settle on 1.1 or 1.2 gas setting. Before you start anything, ensure that when you assemble the SVT-40, you cannot turn or adjust the gas regulator without tools. If it wobbles, changes on its own, or can be adjusted with your hands, your seeping gas – no if’s ands or but’s. You can test it out if you want, by spraying soapy water on the gas system to test. If bubbles appear/grow your seeping gas. In fact, that is how we will be testing and tuning this system, but more on that in a little bit. Secondly, the piston nozzle should be tight that you cannot remove it without a wrench. This guide assumes that the regulator and piston nozzle is set in securely, and cannot be moved without tools and that the regulator is on a setting, such as 1.5.
1 – Spray gas regulator system / piston assembly as shown in Figure 1. You will likely notice bubbles on one side or the other. This is your first area of seepage.
• If it is on the regulator side, I have found a paste lube, like Frog Lube paste, or Vaseline, or gun grease can seal this section off nicely. Be careful not to plug the regulator, you just want to cover the outside of it to seal it off. I prefer Frog Lube, as it is very easy to clean off and reapply later on, and in case of heat buildup from trapping too much gas, will liquefy and not impede operation, while still sealing.
• If it is on the piston nozzle side, you either did not tighten it enough, or you need some Teflon tape on the threads to seal it off.
2 – The fit of the nozzle and the cup set is crucial. If you put your finger on the assembly end of the piston, and fit it in the cup (Fig 2), when you squeeze, there should be a bit of pressure buildup when you compress them together. If so, you should be good to go.
Every bit of gas should push the cup/rod back and when the gas pressure neutralizes, reverse on its own from the return spring tension. I have seen where the pressure was too high (1.7) once at the range on a fellow shooter’s rifle and the cup got caught on the nozzle groove, which got slammed when the bolt tried to close. Actually bent his op rod from this, so please be careful with a high pressure setting.
• If you don’t have compression, it is caused by a loose fit. I have swapped cups on two rifles (breaking serial matching I know!) but they were a much better fit, and increased the reliability of the rifles. Perhaps they recycled parts on some SVT’s causing this then forced matched them, I just don’t know. A bit of Frog Lube Paste on the outside of the nozzle fitting in the cup can create a good seal if that is the case (fig 3). I have also bought a replacement stainless steel cup and piston from http://www.ppsh41.com/SVTitems.html these have the compression you’re looking for, and resists corrosion much better than stock parts.
3 – Next up is quite simple, just put a light film of CLP on the op rod and return spring rod to keep operation smooth and reliable. Check to ensure the OP rod is not bent, if so carefully straighten it to smooth out operation.
4 – Clean, and keep your chamber clean. That fluting really mucks things up, and once runs hot, can cause some lacquered casings to stick, or if very soiled, create an excess of pressure around the case neck preventing easy extraction. I have seen range day’s ruined from owners not willing to smack the bolt handle to overcome the pressure. I found the best to clean it for me is your favorite solvent (mine is Butch’s Bore Shine) and using an Otis chamber brush like this ( http://www.otistec.com/pc_product_detail.asp?key=B548D247B18C4146BD0912FACFF29EEB ) works very well. Saturate it the brush with your solvent, put it on one section of a three piece rod, and a drill and let her spin. You will be surprised on the junk that can come off. Clean this very well, then cover the brush with a patch, and wipe everything off, then coat with CLP. This will make it easy to keep clean in the future. I have found that I need to repeat these processes at the end of every spam can (440 Rounds) for optimal operation.
--- This should end your FTE problems for your rifle, and allow you to get to the lowest gas setting. If you cannot get to 1.1, but you are on 1.2 and your still using the stock piston nozzle and cup, you are doing very well, and should be proud of your rifle, you have a good one, and have tuned it up to the most it can be (to my knowledge) The grouping reduction between 1.2 and 1.1 is negligible in my experience and ability. At this point, I think bore condition is the biggest culprit, which I can deal with in another article. I strongly recommend the stainless system if you want to get to 1.1, as it will, and seriously increase your after shooting cleanup pleasure with how easy it is to clean.
I know this is beyond what I said I would touch on, but in the spirit of getting it to operate the most reliably, I shall continue. This deals with the FTF problems some rifles suffer from.
5 –Take your magazine apart and clean it very well. Sometimes they need a bit of lubrication for the follower to not get caught up on a rusty/dirty spring, or pinning methods. Here is video on how to disassemble your magazine. (https://www.youtube.com/watch?v=GCrv1MsKjY4 )
6 – Take the receiver and use a brush with solvent and clean everything in the general magazine/bolt/operational area. I have found that dirt and grime can gum things up to mess up feeding. Lightly oil it up after cleaning, ensuring a smooth operation. Too much oil and it will just capture crap and get gummed up again. I have found dry Teflon lube to be good for this, since it doesn’t stay wet.
7 – Verify how it feeds with your magazine in. On one rifle, its magazine needed to have some material on the back of magazine removed, as the bolt was slamming into the mag when trying to feed. Take your time doing this, as too much might make a bullet not stay in (never witnessed it, but I imagine it could, and ruin a mag) you want to modify the magazine, not the bolt and carrier in every case! Polish whatever location your moved metal, bevel it if possible and apply some lube (dry lube if you have it) Fig 4 shows possible culprit areas
8 – If you are still experiencing your bolt not completely closing (like, ¼ inch away from closing) your bolt carrier group springs are either bunching, or weak from age. First step is to create a slight bevel on the middle spring connector, to prevent bunching, and apply some lubricant. If that doesn’t do it for you, or your springs are very easy to compress, time they be changed. PPSH41.com makes the replacement springs, and they cure all the problems of bunching or weak springs. Highly recommended as an upgrade.
This should end your FTF problems, as far as my experience goes on the SVT platform. If you still have FTF problems after changing springs, go back to the magazine, it’s your most likely culprit.
Following this guide, you should be able to resolve your FTE and FTF problems, as well as greatly reduce the impulse vibrations from a high gas setting. As we all know, the less vibrations, the greater the precision. I have witnessed on several occasions where after this detailed cleaning and tuning, that rifles set on 1.5 and 1.7, actually send the bolt carrier to slam into the back of the receiver. A heavy clunk and a discordant vibration will occur. Lower your gas setting immediately to prevent damage to the rifle and its internal parts.
The half dozen or so rifles that I have performed this too, all shoot surplus rounds, from many different countries, with more than satisfactory performance from this beautiful and reliable surplus rifle. I have found that at the 1.1 – 1.2 marks, the tangent sights also more accurately reflect the bullet drop, increasing long range accuracy.
Figure 1
Figure 2
Figure 3
Figure 4
