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Education / Training Slavia 618 breakbarrel air rifle: Part 2

Slavia 618 breakbarrel air rifle: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Slavia 618
Slavia 618.

Part 1

History of airguns

This report covers:

  • Before the test
  • RWS Basic
  • How does it shoot?
  • Crosman Premier Light
  • Discussion 1
  • Re-test with the “new” seal
  • Basic test 2
  • Premier Light test 2
  • Discussion 2
  • Cocking effort and trigger pull
  • Summary

Today I test the velocity of the Slavia 618. You will recall that I have two of these rifles and one seems to be performing well. That’s the one I’ll test. The other rifle I will rebuild, but we will look at that in a separate report some time in the future.

Before the test

This rifle has a leather breech seal which is indicative of a leather piston seal, as well. So I dropped about 5 drops of Crosman Pellgunoil down the barrel and stood the rifle on its butt for a few days to let the oil run down into the compression chamber and soak into the leather. It also soaks into the breech seal as it passes, softening it up so it can do the job it was designed to do. That should get the rifle into the best possible condition for a velocity test.

Slavia 618 old breech seal
The old leather breech seal was dead flat. I oiled it but shot the rifle with it in place.

RWS Basic

The first pellet I tested was the 7-grain RWS Basic wadcutter. They averaged 410 f.p.s. from this rifle. The spread went from a low of 395 to a high of 427, so a difference of 32 f.p.s. At the average velocity this pellet developed 2.61 foot-pounds at the muzzle. As ugly as it looks, it is a shooter!

How does it shoot?

The rifle shoots calmly without vibration. It’s rather pleasant to shoot, actually. It’s light and quick and the trigger feels decently crisp. It cocks with a light pull on the barrel and when the sear catches its crisp and positive.

Crosman Premier Light

Now it was time to test the rifle with a heavier pellet. I selected the 7.9-grain Crosman Premier Light for this. Premier Lights averaged 392 f.p.s. with a 70 f.p.s. spread from 361 to 411 f.p.s. That’s pretty crazy! At the average velocity this pellet generated 2.7 foot-pounds at the muzzle.

Stock up on Air Gun Ammo

Discussion 1

This 618 is performing well for its age. But that flat breech seal had me wondering if there was more performance that was being robbed by loss of compressed air.  So I did an old spring-gunner’s trick. I removed the leather seal.

Slavia 618 breech seal out
The old leather seal has been removed from the 618’s breech.

Slavia 618 leather breech seal
The leather seal is pretty decrepit!

And here is the trick. Leather seals can look horrible and still be made to do a good job of sealing the breech. I put two paper shims under the seal, flipped it over so the face that was exposed was more uniform and reinstalled it. Now the seal is more uniform and stands taller.

Slavia 618 shimmed breech seal
The inverted and shimmed breech seal now stands taller and is more uniform.

Re-test with the “new” seal

I felt it would be good to test the 618 again with the new seal, now that it was taller and more uniform.  I will test with the same two pellets.

Basic test 2

This time RWS Basic pellets averaged 433 f.p.s. — a gain of 23 f.p.s. The spread this time went from 429 to 440 — a difference of 11 f.p.s. That compares to the spread of 32 f.p.s in the first test. At the average velocity this pellet now produces 2.91 foot-pounds. Refreshing the breech seal has increased velocity and cut the variation by two thirds. I’d call that a result!

Premier Light test 2

Premier lights averaged 405 f.p.s. this time. That’s a gain of 13 f.p.s. The spread went from 383 to 415 f.p.s. — a difference of 32 f.p.s. That compares favorably to the 70 f.p.s. difference in the first test, though I will say that the Premier pellet does not seem suited for this air rifle, no matter how well it shoots. Premiers now develop 2.88 foot-pounds at the muzzle.

Discussion 2

My point in doing all of this is that this Slavia 618 seems to be in fine shape for an accuracy test. No, it’s not recently rebuilt, but it out-performs other 618s that have been. That is what a little oil can do for a leather piston seal. I have seen leather seals that could have been as much as a century old revived by oiling. I have also seen them crumble into a pile of dust from dry rot, so their past does play a big part in whether or not they can be brought back.

Of course the seal trick is just that — a trick. The breech seal should be replaced before long.

The rear sight on this rifle is the one that was bent to the left. I will swap it for the rear sight on the other rifle that seems to be okay. And then I will conduct the accuracy test.

Cocking effort and trigger pull

This 618 requires 12 pounds to cock it. That’s light enough for small children. The single-stage trigger pull on this rifle measures 3 lbs. 5 oz. While that doesn’t sound that light, the break is clean and crisp and I find it delightful.


We have a good one here. It wants to shoot lightweight pure lead pellets and I bet it can shoot them well. We shall see!

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

45 thoughts on “Slavia 618 breakbarrel air rifle: Part 2”

    • AP,

      Two of my old rifles have leather seals and I have toyed with the idea of replacing them. One thing I ponder is whether a modern piston seal will produce more power. Then I think, who cares. They are shooting at slightly above the power level of a modern 10 meter air rifle. They were designed for 10 yard shooting competition. They do a pretty fine job at 25 yards.

      Leather seals really do work just fine at the lower power levels. If they do happen to go bad, it is pretty easy to make a new one where ordering a synthetic replacement can be difficult and more expensive. It is much more funner to make your own.

      Now, having said that it is my intention to go inside my 1906 BSA soon and see if I can correct a minor issue I am having. I am considering trying a synthetic piston seal just to see if it is an improvement. I will be sure to let you guys know if it does.

      • “…it is my intention to go inside my 1906 BSA soon…”
        I, for one, would like to see some pics of the inside of that ol’ gal…and I’m sure there are others here who will feel the same way.
        Hoping she comes out even better than she goes in,

        • Dave,

          Me too. That is why I am going in. I mostly want to work on the sear engagement, but I have also been thinking of shortening the spring and maybe a synthetic seal. We will see.

  1. B.B.,

    This one does sound like a pleasant gun to use all day for plinking. Maybe on the third part you can show a picture of this side by side with a Diana 27?


    • Siraniko,

      Yes, the 618 is a pleasant plinker.

      In the late summer, early fall we would have grasshopper competitions (a tin of pellets, 1 point for a hit minus 1 point for a miss and no point if you took more than 2 seconds to aim and shoot – best scores were in the low to mid 400s) and shooting 2 – 3 tins a day was typical.

      Can not even guess how many hundreds of tins I have put through my little 618 and though it is a bit tired (needs a new spring ) it still shoots well.


      • Hank,

        You definitely have a bond with your 618. I was the same way with my Benjimin 312. Shot it most every day for quite a few years as a kid.

        My grandson had a good time hunting grasshoppers with his Red Ryder a few years ago.

        I may get some time to work on my 100 yd range today. That means I finally have internet access at the cabin. It is slow but works.


        • Don,

          Yeah, you really get to know a gun if you shoot it every day. Was easy when there was only one gun, now I have to be sure they all get equal attention or there will be distention in the gun safe and all kinds of complaints!

          Great for the 100 yard range – and 15 inch hold-overs!! My long range shooting lane and back stop are almost finished – decided to remove one more tree that is crowding the lane and shading the target too much. I put up steel plates at 75 and 128 yards – fun to ring them! I promised GunFun1 some pictures so you will see it soon.

          Hey, thought the cabin was a get-away from high-tech place, what is with the internet in there? Slow but works… me to – can relate to that LOL!


          • Yep Kate and I went out on the dozer to clean up a little and knock down some dead trees I can cut up to build a better backstop. Now have plenty of logs.

            But Kate got off the dozer when it got a little rough and forgot her bag with her Crosman Vigilante pistol in it. The bag fell off and I ran over it. So the internet service helped me reduce the scolding. I already ordered her a new pistol. Tomorrow I plan on cutting up six or eight good sized logs to stack for a good backstop.


      • “Yes, the 618 is a pleasant plinker.”
        She sure seems like a sweet little rifle; I’m curious to see the accuracy testing, but also to see how the rifle B.B. is currently testing will stack up against the rebuild of his second 618.

        • Dave,

          I’m curious as well – back then there was only one pellet available locally so it was what it was.

          I causally plink with my 618 and never tried different pellets – plan on doing some testing now 🙂


  2. B.B.

    I know about the tissue test, where you place a piece of tissue paper over the barrel lock-up and shoot. If the paper is blown away your breech seal is leaking. However, you just eyeballed it?
    Maybe the piston seal is in as bad or worse shape?


    • Yogi,

      Most of the time when you put oil into the chamber of a leather piston seal, it will soak it up causing it to swell and become pliant, making for a seal. Now, if the leather piston seal is “shot” you will find your oil running out the back of your action or around the trigger as it has stood in the corner not being soaked up.

      Also, as with a synthetic seal you will notice a drastic reduction of power when the seal gives away.

        • Yogi,

          Not if the seal is still good. I guess it is possible to overdue it, but if you do your bore will be well oiled also. Because of the oil, the leather seals are not good for the “high power” sproingers, but if your normal operating level is around 400-700 FPS they are just fine.

          You get above that and the oil starts dieseling and you can risk detonations. Not good. I had a detonation literally blow out all of my seals on my Gamo CFX.

  3. My Diana 25 does not appear to have a seal around the breach. I am thinking that it is a pre-WWII gun that was a GI bring back because it doesn’t have Made in Germany anywhere. Also picked up a Crosman 700 CO2 rifle that has a medium leak so I tried the Pellgunoil oil trick. Seems like a fun shooter when I
    tried it. Really unique mechanism. If that doesn’t work, I’ll try the ATF trick.


    • Mike

      Watch out for that adjustment screw !!!!!
      They lock it into place by bending the metal tab that the screw threads through. You will chew up the threads on the screw if you don’t bend the corner of the tab back straight. When you have it right, you can bend it back down a bit to lock the screw.
      Be careful you don’t set the trigger too light. A Rekord will back up to fully reset if you have pulled the trigger part way then release it if it’s set heavy enough. If the trigger only resets to part way (trigger does not return to full foreward position) then it is set too light and is dangerous.


    • Mike,

      Twotalon is spot on. If you’re trying to adjust the large silver/gold screw (depending on your R9 model) behind the trigger it’s frozen in place by the Weihrauch factory installed threaded tab. It needs to be bent or you will deform your adjusting screw. BTW, this is only one of 4 adjustments on the rekord and if you want to adjust it properly you should take the trigger out of the gun to make it easier to adjust. Bending and rebending the locking tab can only withstand several trigger adjustments before it no longer locks that adjustment screw in place. Here is a good write up on solutions and adjustments. Look for the lengthy reply by NCED (Ed):


      • You were right, that took care of that issue. The peep sight I had didn’t fit so I mounted a TASCO Red Dot that I had in reserve. I’m getting about one hole groups at 12 yards. This R9 really likes the H&N Field target trophy with 4.51 heads. That’s great since it’s the same pellet the FWB 124 likes. This rifle will work well for me. Fairly light, 177 cal., Peep for Red Dot sight, good trigger. I will shoot it for a while to break it in. It has a fair amount of “Buzz” so I will probably apply some “Tune-In-A-Tube” after a while. That worked well on the 124. The trigger adjustment is OK for now so I will tune it better later.
        Thanks all for the links and information.


        • Mike

          You might want to get a tube of blue Loctite for the screws . Both of my R9s were bad buzzers and prone to shaking the screws loose in short order.
          DO NOT overtighten the rear trigger guard screw. Snug is good.
          I ended up installing Vortek kits in both R9s. I cleaned out both of the tubes with Gun Scrubber to get rid of the thick factory grease first.

          The barrel hinge will loosen up on you. Mine took several adjustments before the hinge got stable .

  4. Mister AP ,

    It is not a good idea to convert a leather gun to synthetic seals . In guns with leather seals the tubes will be more polished than cross hatched . Sometimes a synthetic seal will not seal well or is just a bit undersized , the leather seals when oiled well will swell to the tube and also are more durable then a synthetic seal . BB is best to let sleeping dogs lie in this case , nothing to be gained for the effort .

    Gene Salvino

    • Not to mention how often in older guns the compression tube is out of round. A leather piston seal can “conform” much easier to an out of round tube than a synthetic seal.

  5. Kevin ,

    True , the leather can conform very well . The leather seal also works like a parachute seal and gets forced out against the walls . People take for granted how hard it is to drill a straight hole !

    Gene Salvino

  6. So nice to see this test.
    It’s been thirteen years now since I first found your website B.B. and I had purchased my first ‘good’ gun, a Slavia 630. Many guns later (and graduating to powderburners) our favorite to do just a little backyard plinking is still that Slavia, which still gets pulled out at least a couple times a month.

    • CSD,

      I have become fascinated looking at Dawson City from Google Earth! It seems like such a quaint and neat place. Robert W. Service wrote from there, you know. “A bunch of the boys were whooping it up in the Malamute saloon!”


      • I know a few people who’ve been there and all said it was one of the best experiences of their lives…. but that to really appreciate it you had to drive there.
        Our trip was to be a month because after Dawson we were going to continue on to Tuktoyaktuk, a village that is on the Arctic Ocean. Til two years ago you could only drive there in the winter when the muskeg was frozen, but now they have a gravel road that allows year round driving…. though I’ve heard stories that in a bad rainstorm the ‘road’ can turn into mud 18” deep. https://en.m.wikipedia.org/wiki/Tuktoyaktuk
        Hopefully next year if we get a handle on this dam virus.

        • CSD,

          I always wanted to head north and just see how far I could get. I would want at least 3 or 4 vehicles in a caravan though. I met a guy in Alaska with a camper on an old diesel truck that was 4 wheel drive. It seemed like the perfect vehicle for that kind of venture.


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