GTA
All Springer/NP/PCP Air Gun Discussion General => European/Asian Air Gun Gates => Czech & Russian Air Guns => Topic started by: AmBraCol on February 11, 2014, 11:16:44 AM
-
I'm curious as to what muzzle velocity you are getting in your Izzy. I've been having problems getting decent accuracy out of mine, no matter what pellet I use. And no, it's not a case of someone who can't shoot. I'm no Olympic grade 10M competitor, but off a rest I can do more than decent work. A while back I shot the Izzy over a friend's chronograph and it was somewhere in the low 300 fps range - if I recall correctly. Also I ran it with the Android chrony app that uses sound and it was around the same range. I'm wondering if the low velocity might account for the lack of accuracy in this pistol. Also, what would it take to boost the velocity? Would I need to swap out the rubber cup on the pump piston? The old one looks OK, but perhaps it's at the end of its service life. It's a 2003 gun and using the original parts.
-
I would not want to guess as to the life span of the original seals and other parts of the Izzy. Mine is still humming along just fine after 6 or 7 years. But I have chronographed mine and I get right at 460 to 475 fps depending on pellet. The Vogels I use most often get right around 470. My particular gun needs a slightly undersized pellet. I shoot 4.49 mm pellets. It does not shoot as well with 4.50 mm pellets. But I would not expect that difference to affect the velocity as dramatically enough to get down into the velocity range you are talking about. Changing the seals would be he first thing I would try.
-
My IZZY 46M shoots 452 f/s with RWS r10's. I have no complaints about its accuracy.
-
My first 46m shot hobbies at 380. I returned it for a new one. The chrono from PA of the new one showed 470. When I tested I was getting 410-420. The altitude i shoot at is around 5000 ft msl.
After wander ing the web on what to do I found that you can adjust the power of the 46m. The cylinder that holds the cup seal is threaded on to another cylinder that attaches to the pumping link. I was able to bring the power up to 460 with hobbies. When you unscrew that barrel out like that you can start to feel the cup seal start bottoming out in the back of the air chamber.
I've put the speed back to 410 to ease stress on the seal and the pumping arm. I'll probably only take it up on comp days.
-
Low 300s, sounds like you need to do a servicing of the pistol.
My first guess is that the piston seal is leaking.
But don't just do that seal, go in and do a full rebuild and replace all the seals.
Or send it in to a shop to get the seals replaced.
-
It definitely sounds like you have problems. Mine does 419 with 8.4gr Meisterkuglens and 455 with 7gr R10s.
-
I bought mine used and it's shooting 498-509 FPS with 7 grain RWS basic diabolo .
-
I have an IZH-46, and when I have not been using for a couple of months, the muzzle velocity drops considerably. I don't have a chronograph to measure it with, but the time delay between the click of the trigger and the ping against the 10m-distant backstop is noticeable. Once I fire about 10 or so pellets it is back in working order once again. The velocity is lower than for a 46M, but the muzzle heaviness is much less. It still gets the accuracy required to perform very admirably under ISSF match conditions, and doesn't cost extra money every ten years for a new air cylinder (or two). I backed the pistol away from the face of the cylinder to make the new seal (which I installed) last longer. I also cleaned all the grease out of the cylinder and off of the piston. It is an older pistol, but it still shoots like a dream. Maybe I will eventually sell my LP10 and just collect the different versions of the 46!
-
Shot these the other day:
RWS Meisterkugeln 7.0 WC
1. 485 6. 491 Avg: 490
2. 493 7. 487 Sd: 3.3
3. 491 8. 494 ES: 9
4. 491 9. 490 FPE 3.7
5. 484 10. 490
I guess the variation in pellet weight/fit accounts for the low speed of a few of them.
-
My IZZY 46M shoots 472 fps with RWS r10's.
~ GKU
-
I shoot the IZZY more than 500 times a week.
I cannot afford those high priced pellets.
In fact, soon I will be shooting RWS basics leaving the Meisterkuglen for matches. :D
-
Yeah,
300ish is definately low, even my standard IZH-46 shoots around 420 with 7 gr. RWS Hobby.
-
I shoot the IZZY more than 500 times a week.
I cannot afford those high priced pellets.
In fact, soon I will be shooting RWS basics leaving the Meisterkuglen for matches. :D
I shoot mine a lot also the new daisys are great right there with the basics . They did something different this last year . A new plant or new machines or something but trust me give them a try . I don't have the best scale but its showing 7.716 grains . Here is a link to the pellets it shows the sticker on the tin . Some have the target in a different place and without the different language on the box and I don't know if it makes a difference in the pellets or not but the ones I have are exactly like what you see in the photo with the target at the bottom with the different language on the right side . I was happy to see that dasiy has stepped up in this pellet . I got the tins of 500 for 2.99 so I bought a bunch of them . I thought what the heck not a bad price for practice pellets . When I opened the tin I was very surprised I had to look again to see if I picked up a basics tin by mistake . Before the daisy pellets were way to small and most would fall through the barrel and looked like &^^& . These are the same size as the basics . If I had to I would not be afraid to use these in a match . https://picclick.com/Daisy-BB-GUN-500-Count-Flat-Nosed-177-Cal-174275277056.html#&gid=1&pid=1
-
Paul
My 46M shoots 7.4 grain HN wadcutters at 495 FPS. I consider that close enough to 500 FPS with a 7 grain pellet.
Out of the box my pistol was slower, so I adjusted its compression. This post explains how to do that; and points to a thread on taking the pistol apart: https://www.gatewaytoairguns.org/GTA/index.php?topic=153027.msg155687779#msg155687779 (https://www.gatewaytoairguns.org/GTA/index.php?topic=153027.msg155687779#msg155687779)
Before you take such action, have you applied a few drops of oil to the piston seal to see if that brings up the velocity? I use plain mineral oil. 30 weight non-detergent motor oil is often recommended in the user manual of single pump airguns. Do not use oils that have cleaning solvents in them. Bad for seals, and may burn - if you can get enough compression.
Do you store the pistol with the breech unlatched? The breech seals are known to lose their resilience, if the pistol is stored with the breech latched shut. So, you may need new breech seals, rather than piston seal.
Frank in Fairfield shoots his 46M a lot. From previous posts, Frank's 46M keeps good velocity and consistency. His trick is to store the pistol with an air charge trapped in it, unloaded, with the breech unlatched. I have started leaving mine with an air charge too. The idea is to condition the piston seal to have a close fit with the cylinder bore. Else, mine also shoots slow for about 10 shots before it settles at the normal level; if I have not used it in a while.
-
Side note....Repaired AV46s due back today.
We will see..
-
If your down to 300 then take the seal and piston out and you will see that the seal has collapsed and you no longer have the the 1 mm gap that was there when it was new . The seal should have a flair taper at the front end so its close to 25mm and the bottom end is 24mm . If you notice on your seal its straight with no flair . You don't have to buy another seal just yet ,you don't even need to take it off . Get a 1mm thick rubber band and cut it so its 3mm deep . Use a small screw driver and pry open the collapsed cap as you pry it open use another small screw driver to feed the rubber ban in do this all the way around and cut the rubber band once you have it all most touching so once its all in there is no space and the rubber band is touching each other . Push the rubber band down into the cap about 1mm below the top and put a little bit of super glue in a few places on both sides of the rubber band to hold it in place I used a small sharp metal carving dental tool to tip to pick up a tiny amount of glue at a time . Here is a few photos one shows the flair and the other with the rubber band in place . With the rubber band in place you should see the flair again and it should be back to the 25 mm diameter. Before you put it back in the cylinder put a little but of silicone oil with your finger inside the cylinder and on the seal and feed it in as straight as you can and push on the top of the seal to collapse it to get it started the rubber band will still let it collapse to help get it started in but one in will keep it from collapsing in on itself again . Mine gun got down to 300 and now its at 500 with the 7.0 Meisterkugeln's I got my gun back when it first was sold in the USA back in the 90's new for 275.00 So I have had it for a while now . You should also do the tissue test on the 2 o-ring seals on the cocking level . Once I added the rubber band and reinstalled the seal I was getting 455 so I did the tissue test again and found it was blowing out the tissue on the lower o-ring of the cocking arm . After I added a layer of tape behind the o-ring I stopped the leak and it jumped the fps up to 500 . So just that one o-ring not sealing good cost me 50 fps . I'm really careful to always keep the cocking lever unlocked after I shoot out the pellet so there is no pressure on the seals while not in use but even with it not under pressure while not in use the seal will still flatten out just from shooting it . If you don't know about the tissue test its when you put the thinnest single layer of nose tissue you can get and cut it so it goes over the o-ring with a few mm bigger all the way around and close the lever down and shoot the gun be sure to put a pellet in it because you want all the pressure you can get . If it makes a nice clean hole in the center of the tissue your seals are still good but if it blows it out then your o-ring has flattened out to much . To fix the o-ring so it seals like it should ,I use electric tape . Pull out the o-ring and add 1 layers of thin electric tape and it cut to fit . Make it look like a flat washer . Put them against the back of the slot and put the old o-ring back in . You will see its raised up a little more than it was . Do the tissue test again . If it still blows it out just add another layer of tape and test it again . I have only used 2 layers since I got the gun new .
-
Flair of seal from a side angle
-
Tape cut and placed in the slot . Sorry I could not figure out how to put all 3 photos on the same post
-
Here is a photo I found on this site showing a older seal that has collapsed. If you notice the thickness of the seal from the inside to outside on the out side of the gap hasn't changed at all its still the original 2.5 mm thickness . This was just how mine looked also . The only think that happened was it collapsed and once you fill that space with the rubber band back to the original 1mm spacing the seal is the same on the out side as a new seal again at 25mm . I think maybe if the slot cut was not so deep it wouldn't collapse as easy . I figure the rubber band will keep constant pressure on the seal against the outside . Maybe someone out there could tell me why you would want a seal that has a slot cut so deep and wide that when its used it collapses in on itself and the outer part that touches the metal cylinder never changes ? Don't you want constant pressure against the cylinder wall ? Don't you want the outside of the seal to slowly wear down with pressure against it the whole time ? Anyways Mine is shooting at 500 fps now with the rubber band in the slot, and some tape under the 2 o-ring that on cocking lever . The o-rings they are using are not really o-rings because they are flat on the back side and they are kind of hard so if there isn't a lot of pressure on them the air can come out between the back side and out the side even if its sealed on the front side . Here is how I know this . I did a tissue test and it made a nice clean hole but the power was still lower so I took the o-ringl out and added a single layer of tape behind it and put the o-ring back on . This caused the fps to go up so I figured the air was getting out from the back side . The softer tape seemed to make a good seal between the metal and the hard o-ring . Its good to have a chrony just to be able to see the fps . I'm very happy to have 500 fps with a over 20 year old gun and using the original seals and o-rings . I did see this link with a upgrade kit for some other o-ring I'll probably will be needing in the future . http://www.mac1airgunshop.com/izh-46-valve-upgrade-kit-p/miz46ss90.htm (http://www.mac1airgunshop.com/izh-46-valve-upgrade-kit-p/miz46ss90.htm) . It does say to heat up metal to take it apart .
-
rws45user,
I agree that the wide circular slot in the piston face serves no purpose (beyond what a narrow slot would achieve). However, the wide slot's effect is to lower the effective compression because a lot of air can "hide" in that slot.
So, I think that with a new seal, filling the wide slot would increase velocity more as a function of increased compression, than improved sealing (at least if the seal has not actually collapsed - which yours apparently had).
If the lip of the seal has pulled away from the compression cylinder, then it will leak so much that the air can't even help to push the lip put from the inside of the groove. In that case, the gun basically won't hold air and will battle to shoot the pellet through the bore.
I have been tempted to fill that groove in the piston seal with grease because it is reversible. Your use of rubber to fill it is also reversible, with the added benefit that it should stay put, rather than migrate into the valve. There may be commercial square or X-rings rings that are perfectly suited to this; so thanks for the great idea. For instance:
https://www.mcmaster.com/rings/square-profile-oil-resistant-buna-n-o-rings/ (https://www.mcmaster.com/rings/square-profile-oil-resistant-buna-n-o-rings/)
https://www.mcmaster.com/rings/square-profile-oil-resistant-buna-n-o-ring-cord-stock/ (https://www.mcmaster.com/rings/square-profile-oil-resistant-buna-n-o-ring-cord-stock/)
https://www.mcmaster.com/rings/x-profile-oil-resistant-buna-n-o-rings/ (https://www.mcmaster.com/rings/x-profile-oil-resistant-buna-n-o-rings/)
https://www.mcmaster.com/rings/x-profile-oil-resistant-buna-n-o-ring-cord-stock/ (https://www.mcmaster.com/rings/x-profile-oil-resistant-buna-n-o-ring-cord-stock/)
I have taken to leaving my 46M pressurized when not in use to try and keep the seal from collapsing. Certainly, a seal that can collapse over time seems like a poor design (or material choice). Yes, eventually the synthetic material will go stiff or crack, but it is hardly living a hard life, compared to a springer piston.
-
I don't think the seal collapsing is just on my seal . I got the collapsed photo from one of your post Re: Disassembly of IZM Baikal 46M to change the piston seal. But mine looked exactly like the one you post so I'm sure its happening to all the seals in this gun . I don't know how other parachute seals work but I thought they should wear on the outside that's touching the cylinder not collapse in on itself . I shoot a lot because I'm still shooting matched and I shoot pellet to practice . I probably shoot 1,000 pellets a month I try to shoot 10 pellets 4 times a day so I can't complain about the seal at all . Even when I let it get down to 300 it was still shooting great and if I wouldn't have put it on the chrony I would have never guessed it . It was definitely a very slow decline . I only use the gun for 10 meter shooting and at that distance with 300 fps it was shooting great . I was thinking about leaving pressure in the cylinder also but I wasn't sure how the gun worked . Does the air that is under pressure while cocking it go into a chamber with a one way valve and is trapped so it doesn't matter how long you wait to shoot and you don't lose any pressure around the seal ? I did a few test when it was at 300 . I shot it over the chrony right after I cocked it and with different time lengths because in my shooting routine I shoot , touch my phone app 45 second count down timer , cock and load the gun and set it down , when the timer changes color at 15 seconds I get my grip and when it turns red at 5 seconds to go I raise the gun aim and fire and repeat . So the gun stays cocked and under pressure for about 45 seconds between shots . I waited for a minute and shot it over the chrony and there was no change between the shot right away and a minute wait time I tried it again at 2 minute wait time before a shot with no difference . So even with it down to 300 fps I wasn't losing any air so my shots were consistent . My seal when I pulled it out was straight up and down with no flair at all so I was surprised it was building up pressure at all . I'm going to keep a eye on the chrony and my shot count with the rubber band in there and see how it goes . I'm hoping this time the seal will wear out on the out side and I get another 20 years of shooting with it . I'll be 81 years old shooting my izh with the same seal that came with the gun . That's crazy . I have pretty good luck with seals in airguns I will have to say . I have a rws model 45 hence my name on here in 1987 and I still l have the same leather seal in it and the same breach seal with 2 layers of tape behind it. So its going on 34 years of use with a leather seal . I'm down below 800 now with 7.9 grains so I think its time for the conversion kit to synthetic. I'm starting to get some big spreads of 800 down to 760 . I already have the kit and a new spring I just need to do it .
-
I am sure that all the installed 46M seals of that pattern and material gradually collapse over time - not from shooting.
Even a leaky seal will capture air, if you move the piston fast enough. Once there is some pressure, the seal stops leaking and can generate more pressure. However, speed related compression is undesirable, as it is too easy to introduce variability. If you are very consistent in your charging motion, even a partially leaky sealed pistol could probably shoot OK.
If your pistol can hold air with no change in velocity for a minute, when you usually take 30 seconds to make the shot, then there is no problem. If it will hold air with no velocity drop for 5 minutes, then even better.
I have taken to keeping my 46M charged, based on Frank in Fairfield's experience. I was hesitant to do that, because I had tried it with a Beeman P17. That, extruded the valve O-ring into the valve seat and cause the pistol to malfunction. It would neither discharge, nor charge after that until I had attempted many dry fires. Then it abruptly corrected itself.
So, keeping a SSP charged helping or not depends on the whole system. I think that with the 46M, there is no downside. I have not tried to measure velocity after keeping mine charge for a day, but I do know that it still makes a good pop after being charged for a week. Probably not as loud as charging it and dry firing immediately.
Good on you for shooting the same pistol for so long. The fact that the rest of the pistol lasted so well is impressive. Of course, some people can break anything by applying more force than necessary. I know that opening the 46M breech via the end of the cocking stoke feels like one is abusing the pistol to some. It is good to know that it does not mind any force sufficient to operate; repeated 200,000+ times (if you have been shooting 1000 pellets a month for 20 years).
What lubricant do you use on the piston seal and cocking linkage?
-
I only use tread mill 100 % silicone lube https://www.amazon.com/dp/B01IX28D0U/ref=sspa_dk_detail_2?psc=1&pd_rd_i=B01IX28D0U&pd_rd_w=zDkiO&pf_rd_p=b34bfa80-68f6-4e86-a996-32f7afe08deb&pd_rd_wg=NOE0h&pf_rd_r=79177YDVDBYYAGXGA8K6&pd_rd_r=8f88451d-d779-4479-8736-75d2909fdcd8&smid=A2JWZOZUWVCPDC&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFYQ0lMS0VVN1A3MjImZW5jcnlwdGVkSWQ9QTEwMzIwMDJVSzlIVFBLRzNURUQmZW5jcnlwdGVkQWRJZD1BMDQ2MTIyNzNWMjFSSUNZOFJETkgmd2lkZ2V0TmFtZT1zcF9kZXRhaWwmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl (https://www.amazon.com/dp/B01IX28D0U/ref=sspa_dk_detail_2?psc=1&pd_rd_i=B01IX28D0U&pd_rd_w=zDkiO&pf_rd_p=b34bfa80-68f6-4e86-a996-32f7afe08deb&pd_rd_wg=NOE0h&pf_rd_r=79177YDVDBYYAGXGA8K6&pd_rd_r=8f88451d-d779-4479-8736-75d2909fdcd8&smid=A2JWZOZUWVCPDC&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFYQ0lMS0VVN1A3MjImZW5jcnlwdGVkSWQ9QTEwMzIwMDJVSzlIVFBLRzNURUQmZW5jcnlwdGVkQWRJZD1BMDQ2MTIyNzNWMjFSSUNZOFJETkgmd2lkZ2V0TmFtZT1zcF9kZXRhaWwmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl) . It works the best for when rubber and metal come in contact . The lube keeps the rubber from wearing it just slides over it . I don't use much at all . I put a few drops every 500 shots or so around the cylinder walls and cock it back and forth a bunch of times I also add it in the hole where the air comes out of to try to lube up the o-rings that's down in there . After I add a drop or 2 in that hole I cock and shoot without pellets at a box until the lube stops spraying out . after that I clean the barrel with my snake rope barrel cleaner . I also add the lube inside the small tube that's just behind the air hole Here is a photo of it . Its a redish color bar that goes into a tube . Over the years I have noticed that this metal will try to rust or what looks like rust I'm not sure but I get in there and keep that as clean as I can and after I clean it I put lube in that cylinder raise the arm up and down and clean it out again and add more lube till it looks clean . I think its really cheap metal or maybe just dissimilar metal and its causing whats called galvanic corrosion because even with the lube and good low humility room I stay in with the gun I can't see it being anything else , but as long as I keep it flushed out and clean every 500 shots or so It seems to keep on shooting pretty good . I have my own business so when I need to stand up and move around I'll take 10 quick shots as often as I can so some days it more and some days it less but yes the shot count does add up . You would think I could hit where I wanted by now but some days I think I'm getting worse instead of better . It sounds like a lot but 2 tins of 500 is 1000 shots . which is not even close to what I should be shooting . To most 10 meter shooters that's just warmup amount of pellets . I use the cheaper daisy pellets to practice with so your only talking about 5 dollars a month for pellets . For 5 dollars a month I have a lot of fun shooting . Its about the cheapest shooting sport you can do . I really like shooting so I have sure got my 250 dollars worth of fun from this gun . They started selling this gun again but under the air venture name and its a lot higher price than what I paid for it ,but even at its 599.00 price tag I would tell anyone to buy it . Its so worth it if you want a single pump 500 fps gun that will last you forever and put a pellet in the same hole if you can hold it there .
-
Well, if your lube has worked for 20 years, it must be good.
The rear of the piston slides metal on metal in the compression tube. Some might argue that silicone oil is not the best for lubing that. It can't be worse than leaving the parts dry.
Many SSP airguns list non detergent motor oil to lube the piston. Detergent oil or CLP could very well denature the rubber seals. Some use ATF because that conditions the seals. I think a seal neutral oil is better.
I just use straight mineral oil, sold as a laxative and in baby oil; so non-toxic.
Some people use a grease of some kind. I like oil here because I think it flushes out dust that gets drawn in with the air, rather than accumulating it.
Unfortunately, shooting well becomes harder as we age. The important thing is that you are having fun.
-
I didn't realize that the back of the piston metal was touching the cylinder . I will start adding some mineral oil to the metal piston . I was just trying to lube the seal itself not the metal piston behind it . Thanks for that info. On my gun the metal part that holds the seal is a little smaller than the cylinder so I didn't think it would touch anything as I closed or opened it . The inside walls of the cylinder doesn't have any scratch marks or anything . I have never seen any metal scrapings from metal to metal wear , but I will add some of that mineral oil on the piston metal so It doesn't start doing it . I want to do what ever I can to keep that cylinder nice and smooth . I'm pretty careful when I open and close it and I do it pretty slow because I'm never in as hurry to open and close it . I don't want to have to buy another 10 meter gun so I try my best to take care of what I have . I can't believe my gun has jumped from 275 .00 to now 600.00 for the same gun . It does have a nice looking grip on the new guns thats worth 100 bucks right there . I'm left handed and I could never find a left handed grip for the gun so I made one out of the dental material I have in my lab . It looks funny put I formed it from th inside of my hand so you can see the impression of my hand in the grip , its a custom fit just for my hand so I like it and I'm use to it now but I wonder if the new gun grip comes in left hand . I'll have to give them a call to see if I can just get the grip .
-
It may be an idea to add a small amount of moly powder (or grease) to your silicone oil at the rear of the piston. Mixing silicone and mineral oil may cause one oil to reject the other.
Anyway, if your cylinder is not scored, frosty or worn looking, then your oil is working well enough. I would hate for you to modify your method, and actually cause a real problem. See this on mixing silicone and mineral oil:
https://klsummit.com/headlines/2018/mar/faq-what-oils-should-we-avoid-mixing
The ones that don't mix well, the ones you have to be concerned with, are silicone oils and perfluorinated types (PFAE). These are also synthetic oils, but silicone oils will not mix with standard oils like PAO oils, mineral oils, esters, alkylated naphthalenes, polyglycols and OSP.
-
I see thanks. I didn't know that .
-
Do you know where this upgrade kit goes ? Is that the tube I show in the photo I post before ? Also do you know of a video that shows how to replace and add this upgrade ? http://www.mac1airgunshop.com/izh-46-valve-upgrade-kit-p/miz46ss90.htm (http://www.mac1airgunshop.com/izh-46-valve-upgrade-kit-p/miz46ss90.htm)
-
I believe that is the valve body, described as a bushing part number 30 in the attached PDF, from here: https://www.toolfarm.no/ViewFile.aspx?ItemID=890 (https://www.toolfarm.no/ViewFile.aspx?ItemID=890)
More images from different angles: https://airpro.ecrater.com/p/35497975/izh-46-mp-46m-valve-crossbar (https://airpro.ecrater.com/p/35497975/izh-46-mp-46m-valve-crossbar)
Still looking for video instructions to disassemble the valve. So far, I have found these: http://www.pilkguns.com/izh46ex-htm/ (http://www.pilkguns.com/izh46ex-htm/)
I have never felt the need to disassemble the gun that far.
-
Hi all,
Just got a new MP-46M from Krale and I am trying to follow the collective advice for cleaning and getting it to perform to spec.
I have stripped it down and removed the storage grease. Then I lubricated the seals with RWS silicon air chamber lube and applied RWS spring cylinder oil to the mechanical joints. (Though it sounds like the Mac1 formula my be best for this). I confirmed I wasn't getting any obvious leaks at the breech end with a tissue test.
I then checked the piston engagement so that it is getting the maximum compression without mashing the end of the seal.
After all this I am still shooting around 386-389 fps using 8.2 gr RWS R10 match.
I am now trying the conditioning treatment of leaving the chamber pressurized to form the seal. Hopefully this and maybe general wear in will improve velocities. I can try some lighter pellets too. I do not want to go disassembling the valve assembly yet...
Let me know if I am on the right track or if there is something I have yet to try.
Thanks
-
Paul,
Try different pellets. I like RWS pellets, but have had "slow" 7 grain Meisterkugeln before. Slow in everything I shot them from.
The only factory "grease" removal I remember from my 46M manual was the preservation oil in the barrel bore. Expecting you to strip the pistol and remove grease from the compression cylinder seems a bit like asking you to rebuild a new vehicle engine before using it. I would have taken a few shots before changing anything; although I did shoot perhaps 5 cleaning pellets though mine after I got it. The first 2 or 3 were wet with mineral oil to wipe out what looked like a pretty clean bore, out of the box.
The user manual is not very specific about the oil for the piston seal - because the risk of dieseling is almost non-existent: You are not achieving rapid compression, as occurs in a spring airgun. If I remember correctly, the manual that came with my 46M stated non-solvent "gun oil".
As the rear of the piston runs metal to metal with the cylinder, silicon oil may not provide the lubrication the metal parts need. Multi-pump pneumatics often state 30 weight non-detergent motor oil. Definitely not CLP with solvent.
I just use straight mineral oil for the piston seal on my single or multi-pump pneumatics. I know that when I apply too much oil to the piston seal, the velocity actually comes down. Else my 46M does 500 FPS with 7.3 grain pellets. I don't know what viscosity silicone oil you used, or if it has migrated to the valve and barrel. If so, then the oil could have reduced the velocity by chocking off the airflow through the valve and transfer port. Or by increasing viscous drag between pellet and bore. Just shooting it should eventually clear the oil from the valve and bore - although if it is thick and sticky, this may take a long time. Or, it could be another problem:
Did you do your tissue breech seal leak test with a pellet loaded? If not, the air pressure would just escape from the muzzle, without moving the tissue...
I am sure you know that the breech seals are a weak point with this pistol. If you store it with the breech latched all the way shut, the breech seals take a set. The resultant leakage will reduce pellet velocity. When you got your pistol, the breech should have been left with the mechanism just unlatched. If it was completely closed, someone may have handled the pistol and left it that way. Anyway, I suspect that leaving it unlatched will see the seals recover somewhat.
If one of the two breech seals is missing, the pistol my have been fired with the breech not fully latched closed. There should be a spare under the cardboard flap in the original box.
Are you sure that you increased the compression from the factory setting; rather than reducing it? By how many quarter turn increments did you change it? To achieve 500 FPS it took me one more 1/4 turn on the adjustment thread from when the piston seal first made light contact with the end of the compression cylinder. That was two increments from the way it arrived from the factory.
If running the piston seal into the end of the cylinder bothers you; you can fill up the groove in the piston seal face with a sticky grease, so that it takes up air compression volume without running the seal hard into the end of the cylinder. It might have come that way from the factory. You just do not want excess grease ending up in the valve or transfer port, or barrel bore - that would reduce velocity.
Just shooting the pistol may condition the piston seal and the poppet valve to seal better. So, I predict that just using the pistol should increase velocity, but probably not more than 25 FPS - unless there really is too much sticky lube in the valve or bore....
-
For the storage grease removal, I only disassembled the grips and the forward piston assembly and associated misc parts. I flushed the bore and dried it with felt cleaning pellets. The piston and air chamber I scrubbed and ran some of the RWS lightweight silicon oil over. Some of the lightweight silicon oil may have made its way down to the valve assembly. It's not sneezing any oil that I can perceive, but it may take some repeated shots to get rid of any residue. (The silicon products I got to service my PCPs)
The breech seals are new and uncompressed out of the box. I sealed those with a light coating of silicon grease. The tissue test was performed several times while firing a pellet. I have been keeping the pistol stored with the chamber pressurized and the bolt unlatched. I have the included spares and ordered several more on ebay to be safe.
I did not end up changing the factory setting for compression, since I could feel with further adjustment that I was bottoming out and contacting the end of the piston seal. I sealed the end of the piston seal groove with enough silicon grease that it shouldn't migrate further into the action.
I will get some of the non solvent 30 weight oil, mineral oil, or the Mac1 solution, as those sound better for preserving, sealing, and reducing wear in the piston and valve assembly. I will just have to be careful about how much I use and may need to shoot the excess/residue out. I will check for excess grease too when I replace the oil.
After this is done, I'll shoot some of 7 gr pellets and see where I'm at.
Do you know if the b-square rail is available anywhere for the Izzy? I may just need to keep checking ebay...
Also found the attached pdf on the changes made to the piston design over time, It has some great views of the valve and trigger mech.
-
Paul,
I suggest you try a range of different pellets in your pistol. Mine likes the 8.2 grain Meisterkugeln you are using now. It achieves the highest power with H&N 7.x grain "Excite" wadcutters. It even shoots 10.3 grain JSBs at over 400 FPS.
The B-Square rail is scarce because it is no longer made for the 46M. It seems to be available here: http://sunopticsusa.com/airgun-scope-mounts-izh-46-mount-sm7900/ (http://sunopticsusa.com/airgun-scope-mounts-izh-46-mount-sm7900/) That said, with the Air Venture 46M that came on the market recently, the rail may be made in volume again.
Mostly, I am getting dead ends for the rail; such as this: https://www.pyramydair.com/product/b-square-17900-scope-base-weaver-picatinny-rail-fits-izh-46m?a=298 (https://www.pyramydair.com/product/b-square-17900-scope-base-weaver-picatinny-rail-fits-izh-46m?a=298)
Thanks for the link to that PDF. Someone was looking for that info not long ago.
You can always increase the compression later. Mine definitely ran the piston seal into the comp chamber end wall firmly to reach 500 FPS.
-
More potential sources for B-Square rail:
https://www-bhphotovideo-com.cdn.ampproject.org/v/s/www.bhphotovideo.com/c/product/1491840-REG/sun_optics_sm7900_izh_46_barrel_mount.html/amp?amp_js_v=a6&_gsa=1&usqp=mq331AQFKAGwASA%3D#aoh=16029957645794&referrer=https%3A%2F%2Fwww.google.com&_tf=From%20%251%24s&share=https%3A%2F%2Fwww.bhphotovideo.com%2Fc%2Fproduct%2F1491840-REG%2Fsun_optics_sm7900_izh_46_barrel_mount.html (https://www-bhphotovideo-com.cdn.ampproject.org/v/s/www.bhphotovideo.com/c/product/1491840-REG/sun_optics_sm7900_izh_46_barrel_mount.html/amp?amp_js_v=a6&_gsa=1&usqp=mq331AQFKAGwASA%3D#aoh=16029957645794&referrer=https%3A%2F%2Fwww.google.com&_tf=From%20%251%24s&share=https%3A%2F%2Fwww.bhphotovideo.com%2Fc%2Fproduct%2F1491840-REG%2Fsun_optics_sm7900_izh_46_barrel_mount.html)
https://www.tactical-store.com/ts-86-mt-sm7900.html (https://www.tactical-store.com/ts-86-mt-sm7900.html)
-
Nice find with the Sun Optics version! ;D
Special order from B&H, but it looks like it will only take a couple weeks and the price is right. Crossing my fingers.
I'll let you know how the adjustments work once I get some of the other lubricants in.
-
Well checking back in after I replaced the silicon oil in the piston, air chamber, and valve assembly with Mac1 valve oil. After conditioning the piston seal by keeping it pressurized, I was able to record a max velocity around 443 FPS with RWS 7.0 gr Meisterkugeln. Below is a rough chart of the velocities I recorded across various brands (RWS, H&N, JSB, Crossman Premier). I might need to adjust the compression to get more speed (factory stock now) or their might be some more wear-in that needs to happen. I've only put maybe 600 rounds through it. I also ordered some 7.4gr excites to test next.
.177 Rough Velocities
Pellet Weight (gr) Min V. (FPS) Max V. (FPS)
7.0 430 440
7.4 420 430
7.6 415 425
8.2 408 412
8.6 395 400
-
Paul,
Your velocities are now within 10 or 15 FPS of what my 46M produced out of the box. Then I increased the compression by two increments (half a turn on the threaded adjuster). Then I got either side of 500 FPS with H&N 7.4 grain Excite wadcutters.