Nitro venom rebuild
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Topic: Nitro venom rebuild (Read 7008 times))
Treb37
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Posts: 162
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Real Name: Bert
Nitro venom rebuild
«
on:
April 14, 2012, 02:00:30 PM »
Now that I have two piston seals on order I am wondering if there is any good info on re-assembly of this rifle. I have some moly paste for the metal to metal friction areas but what if any should the new seal be lubed with and where might I find those piston rod guides that I've heard about that keep the gas ram centered in the piston?
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Sharp Shooter
Posts: 711
Real Name: Sam B
Re: Nitro venom rebuild
«
Reply #1 on:
April 15, 2012, 09:26:15 AM »
Gene sells the GRS (Gas Ram Saver) on his website
www.airguntoys.com
I don't lube my seal. It is synthetic. All lubrication should remain behind seal to avoid detonation issues in the compression chamber.
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Treb37
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Real Name: Bert
Re: Nitro venom rebuild
«
Reply #2 on:
April 15, 2012, 05:54:21 PM »
Ok what about adding a washer to the gas ram retainer cup? Would this give a similar affect to shimming a spring? I'm down a few fps here at nearly 5000 ft ASL just wondering if I could get a few fps back without retrofitting the XL gas ram. I also notice the face of the piston in the center of the seal appears to have hit the end of the compression chamber more than a few times...is this normal or is that further proof that the seal is shot allowing overtravel of the piston?
«
Last Edit: April 15, 2012, 06:21:15 PM by Treb37
»
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Sharp Shooter
Posts: 711
Real Name: Sam B
Re: Nitro venom rebuild
«
Reply #3 on:
April 15, 2012, 06:22:27 PM »
I haven't shimmed the ram, as you suggest. I've heard of others doing it. Dimes seem to be the right size. However, I don't know how much you actually gain by shimming it.
As to the scarring on the face of the piston -- are there corresponding marks in the end of the compression chamber? If not, the face of the piston may have been marred prior to assembly. If there are matching marks in the compression chamber, I'd say, yes, that is further proof that the seal is shot, unless you dry fired it or have been using lightweight pellets.
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Treb37
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Posts: 162
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Real Name: Bert
Re: Nitro venom rebuild
«
Reply #4 on:
April 15, 2012, 06:40:55 PM »
Yes the marks are corresponding on the cylinder ....never been dry fired or used lightweight pellets. I did also just noticed a couple groves in the compression chamber that correspond to the cocking grove on the piston....
Since I found the bad seal I'm having airgun withdrawls....been on the verge of going over to Wally world for two days to buy a titan gp to fool with since it has all the same parts as my venom but in .22
«
Last Edit: April 15, 2012, 06:45:16 PM by Treb37
»
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Sharp Shooter
Posts: 711
Real Name: Sam B
Re: Nitro venom rebuild
«
Reply #5 on:
April 15, 2012, 08:15:51 PM »
Clean out that compression tube really well with Goo-Gone. There are probably metal shavings in there from the China-lube. You can flush out the Goo-gone with hot water, just be sure to dry it out good. Denatured alcohol or mineral spirits will remove any last bits of gunk. Clean up the piston before you install the new seal. Deburr any rough spots. Follow Gene's instructions for installing the GRS. Lube everything with moly paste as you reinstall the piston, keeping the lube behind the seal as everything goes in.
I know what you mean about the withdrawals. I didn't tear into my Titan until after my wife gave me an NPSS for Christmas (couldn't stand the thought of not having a shooter).
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Crosman Titan GP .22 -- GRTIII "Gateway drug"
Reminton NPSS .22 -- CBR "Clang"
Diana 34 T06 .22 (x2) -- TWINS!
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Disco .22 w/ BNM -- "Easy"
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Treb37
Plinker
Posts: 162
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Real Name: Bert
Re: Nitro venom rebuild
«
Reply #6 on:
April 15, 2012, 09:24:31 PM »
Just out of curiosity and knowing I may get lambasted for this question......Why moly paste....wouldn't a dab of hi temp bearing grease or the like be just as effective?
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Remington npss .22 home tuned
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1st gen XS60c
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Sharp Shooter
Posts: 711
Real Name: Sam B
Re: Nitro venom rebuild
«
Reply #7 on:
April 16, 2012, 10:50:28 PM »
I'll have to defer to the vast knowledge of others on this site to answer that. Probably due to anti-friction, anti-corrosion properties, but that is just a guess.
Some bearing greases do have molybdenum in them.
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Crosman Titan GP .22 -- GRTIII "Gateway drug"
Reminton NPSS .22 -- CBR "Clang"
Diana 34 T06 .22 (x2) -- TWINS!
Beeman R1 .22 -- "Mein Fraulein"
CCS 2400KT .22 -- "Baby"
Disco .22 w/ BNM -- "Easy"
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Treb37
Plinker
Posts: 162
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Real Name: Bert
Re: Nitro venom rebuild
«
Reply #8 on:
April 20, 2012, 03:17:55 AM »
So after going through airgun withdrawls for the past week, my piston seal finally showed up today. I cleaned up and deburred the compression tube, piston and gas ram while I was waiting for the seal to arrive. I didn't replace the barrel pivot plastic washers since there appears to be no wear and they are still working fine after 6500 rounds. Thanks to whomever it was that suggested heating the new seal with a hair dryer to make it pliable enough to get onto the piston. I'm sure it would be easy to ruin the seal if it wasn't warmed up. New seal installed in the freshly de china-lubed chamber. Just a dab of moly in all the right places thanks to a veteran airgunner friend of mine....(Thanks Doug) and the preliminary results are looking like it may be more accurate than ever!! My biggest fear was that it would never shoot well again no matter what I did. I'll find out more tomorrow when I stretch out the range a little more but the indoor 10 yd results look promising. On a side note I tried some jsb diabolo pellets that were shooting well before but now seem a bit more erratic and the 10.5 gr crosman hollow points that it really liked for a while then went way south, are grouping well again. I suspect that when the 10.5 gr cphp's started flying all over the place is when the piston seal started to go south.
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Greeley Co.
Crosman 760
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Crosman/Remington Airmaster 77 home tuned
Crosman Nitro venom dusk GRTIII, home tuned
Remington npss .22 home tuned
QB79 /ninja .177 Home tuned 15 fpe
QB78/ ninja .22 full valve mods 35 fpe
1st gen XS60c
Gauntlet .25 STK full tune and 4500psi CF bottle
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Sharp Shooter
Posts: 711
Real Name: Sam B
Re: Nitro venom rebuild
«
Reply #9 on:
April 20, 2012, 12:53:41 PM »
Don't get too worked up over velocity or accuracy yet! That new piston seal needs a couple hundred shots to settle in good. Run the cheap ones through it first. After a tin of 200 or so, see how she groups.
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Crosman Titan GP .22 -- GRTIII "Gateway drug"
Reminton NPSS .22 -- CBR "Clang"
Diana 34 T06 .22 (x2) -- TWINS!
Beeman R1 .22 -- "Mein Fraulein"
CCS 2400KT .22 -- "Baby"
Disco .22 w/ BNM -- "Easy"
Custom 2240 -- Hers
Custom 2250 carbine -- Hers
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gamo2hammerli
GTA Moderator
GTA Senior Contributor
Posts: 6322
Re: Nitro venom rebuild
«
Reply #10 on:
April 20, 2012, 01:24:41 PM »
Off topic....the stats above is messed up on a wide screen monitor. On a smaller screen it`s fine.
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Treb37
Plinker
Posts: 162
Ready!... Fire!.... Aim!
Real Name: Bert
Re: Nitro venom rebuild
«
Reply #11 on:
April 20, 2012, 08:22:27 PM »
Got a couple hundred rounds thru it today....seems to be more accurate than before. I think the seal had a defect in it that affected some shots and not others. With the new seal shots are more consistent and my old favorite cphp's are right back at the top of the list again. Dunno why but they sure shoot well in my gun. I think there's a perception that anything you can buy at Wally world is junk so cphp's get a bad rap for the neighborhood they live in.....
Anyhow back to shooting paintballs off golf tees hitting about 65% at 35 yds and about 95% at 25 yds. I must have gotten extremely lucky to get one that has lasted over 6500 rounds shoots pretty accurate and only needed a new piston seal because I used Rmcoil when it was new and I think that's what damaged the seal.
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Greeley Co.
Crosman 760
Crosman 1377
Crosman/Remington Airmaster 77 home tuned
Crosman Nitro venom dusk GRTIII, home tuned
Remington npss .22 home tuned
QB79 /ninja .177 Home tuned 15 fpe
QB78/ ninja .22 full valve mods 35 fpe
1st gen XS60c
Gauntlet .25 STK full tune and 4500psi CF bottle
BmaS
Oh no! I've been demoted to
Sharp Shooter
Posts: 711
Real Name: Sam B
Re: Nitro venom rebuild
«
Reply #12 on:
April 20, 2012, 09:42:31 PM »
Way to Go! Glad to hear she's tightened back up for you. CPHP are not bad pellets. My guns do okay with them, some better than others. The challenge is to find the pellet that your gun likes best, for your shooting purposes. I get poor results from JSBs in all three of my .22s. RWS super H points seem to be the "happy medium" I've settled on for my purposes. I get decent accuracy and decent speed. They aren't the fastest, but fast enough. They group as good as I can shoot. And in my penetration testing, showed excellent expansion. My only gripe with CPHP is that I haven't seen the kind of expansion that I expect from a hollow point.
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Crosman Titan GP .22 -- GRTIII "Gateway drug"
Reminton NPSS .22 -- CBR "Clang"
Diana 34 T06 .22 (x2) -- TWINS!
Beeman R1 .22 -- "Mein Fraulein"
CCS 2400KT .22 -- "Baby"
Disco .22 w/ BNM -- "Easy"
Custom 2240 -- Hers
Custom 2250 carbine -- Hers
Custom 2240 -- mine
Crosman 1077 "CO2 sucker" -- Hers
Tanfoglio Witness 1911 CO2 BB -- Hers
Daisy 880 (x4)
Daisy 822 (x2)
Daisy 1200 pistol
Daisy 188 pistol
mtsheron70
GTA Senior Contributor
Posts: 2997
Re: Nitro venom rebuild
«
Reply #13 on:
April 20, 2012, 09:51:50 PM »
That is great! It only takes a very slight nick in the seal to disrupt your fps for sure. To answer the question on moly paste..................I have always used it because, well, the pros say it is formulated for our hobby. I get mine from JM! Great stuff but very very messy. I use nitrile gloves when applying but still manage to get that stuff on my hands!
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mtsheron70
GTA Senior Contributor
Posts: 2997
Re: Nitro venom rebuild
«
Reply #14 on:
April 20, 2012, 09:57:53 PM »
Forgot to mention when I tuned the Benji Trail Sam bought from me I also used a very light sheen of it in the piston compression tube to make sure the piston with the new seal slid in extra slippery to avoid catching any internal burrs that may be there from the factory. I also used brake parts cleaner to clean the compression tube and the piston cylinder before reassembly. An old trick to really clean the internals that I do on building and maintenance of mountain bikes that gets crud and grit all over fine working gears and such. Be careful if you ever use that stuff, one it is flammable, and two it is known to be a cancer causing reagent. The stuff in brake parts cleaner that makes it so good is Tetrachlorethylene. Also used in making meth but that is another world in itself I deal with daily in my job!
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Treb37
Plinker
Posts: 162
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Real Name: Bert
Re: Nitro venom rebuild
«
Reply #15 on:
April 21, 2012, 10:41:56 PM »
Here are a couple pics of the old seal I took out of the Nitro Venom along with a couple pics of my paintball shooting gallery after a day of damage and a 1" target dot 6 shot group all from my 35 yd range. The box behind the 4x4 with the tees in it just has an old bath towel stuffed in it. It works great and my misses arent so loud. As far as the seal goes... this is what it looked like when I took it out. Since it was split it was very easy to remove from the piston. You can see the divot that has been removed from the inner ring that lines up directly with the transfer port. I am sure that detonation from using oil in the compression chamber is what destroyed the seal. The amazing thing is that it was still shooting better than some of the others I've heard of that were apparently in good condition.
Thanks to all who replied, I've learned alot from the guys on here and don't know where I'd go for info if this site was not available....
«
Last Edit: April 23, 2012, 03:17:02 PM by Treb37
»
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Greeley Co.
Crosman 760
Crosman 1377
Crosman/Remington Airmaster 77 home tuned
Crosman Nitro venom dusk GRTIII, home tuned
Remington npss .22 home tuned
QB79 /ninja .177 Home tuned 15 fpe
QB78/ ninja .22 full valve mods 35 fpe
1st gen XS60c
Gauntlet .25 STK full tune and 4500psi CF bottle
Treb37
Plinker
Posts: 162
Ready!... Fire!.... Aim!
Real Name: Bert
Re: Nitro venom rebuild
«
Reply #16 on:
April 23, 2012, 03:20:53 PM »
No comments on the condition of that seal? I thought it would be helpful for anyone else wanting to change a seal. It's not that difficult to do if you have any mechanical aptitude. I was just amazed the rifle would shoot at all with a seal in that bad a shape.
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Greeley Co.
Crosman 760
Crosman 1377
Crosman/Remington Airmaster 77 home tuned
Crosman Nitro venom dusk GRTIII, home tuned
Remington npss .22 home tuned
QB79 /ninja .177 Home tuned 15 fpe
QB78/ ninja .22 full valve mods 35 fpe
1st gen XS60c
Gauntlet .25 STK full tune and 4500psi CF bottle
Treb37
Plinker
Posts: 162
Ready!... Fire!.... Aim!
Real Name: Bert
Re: Nitro venom rebuild
«
Reply #17 on:
April 27, 2012, 11:34:55 AM »
Since I put the new seal, deburred and lubed with moly...maybe 400 rnds later the piston seal is "squeaky" when cocking. And if I break the action and just work it back and forth real slow it will make a terrible noise in both directions. Not metal to metal just like rubber squeaking. Just wondering if maybe I was a little too conservative with the moly paste or is this the norm? It has been shooting better than ever and chrony results show no signs of a bad seal. Average extreme spread is less than 15 fps. I'm not sure if it's connected or not but the Leapers 3-12x40 also appears to be having problems holding zero. It takes what I call "excursions" Just throws pellets in all directions then comes back to zero. Bought a wally world CP 4-16x40 last night and it seems to have solved the excursion problem.
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Greeley Co.
Crosman 760
Crosman 1377
Crosman/Remington Airmaster 77 home tuned
Crosman Nitro venom dusk GRTIII, home tuned
Remington npss .22 home tuned
QB79 /ninja .177 Home tuned 15 fpe
QB78/ ninja .22 full valve mods 35 fpe
1st gen XS60c
Gauntlet .25 STK full tune and 4500psi CF bottle
BmaS
Oh no! I've been demoted to
Sharp Shooter
Posts: 711
Real Name: Sam B
Re: Nitro venom rebuild
«
Reply #18 on:
April 27, 2012, 02:29:16 PM »
I usually only hear that squeaking on the first, sometimes on the second, cocking cycle after a tune. Certainly not after several hundred pellets. You may need to have used a little more lube.
As to the seal pics above, yeah, that is messed up!
I have a Leapers UTG 5th Gen 4-16x50 scope, but I haven't had any trouble out of it since I had the first one replaced under warranty for failure to hold zero. (it got to the point where I could not zero it at all.)
I also have a CP 4-16x40 -- no problems with it.
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Crosman Titan GP .22 -- GRTIII "Gateway drug"
Reminton NPSS .22 -- CBR "Clang"
Diana 34 T06 .22 (x2) -- TWINS!
Beeman R1 .22 -- "Mein Fraulein"
CCS 2400KT .22 -- "Baby"
Disco .22 w/ BNM -- "Easy"
Custom 2240 -- Hers
Custom 2250 carbine -- Hers
Custom 2240 -- mine
Crosman 1077 "CO2 sucker" -- Hers
Tanfoglio Witness 1911 CO2 BB -- Hers
Daisy 880 (x4)
Daisy 822 (x2)
Daisy 1200 pistol
Daisy 188 pistol
Treb37
Plinker
Posts: 162
Ready!... Fire!.... Aim!
Real Name: Bert
Re: Nitro venom rebuild
«
Reply #19 on:
April 27, 2012, 06:59:08 PM »
Well it's not shooting bad it just sounds bad and I'm hesitant to break it down again just to add a little lube. I have a spare seal so I think I will just wait and see what happens or I might get a wild hair and tear it down. I figure the only thing in jeopardy is the seal itself.
I tested both scopes last night. Shot 10 rnds in rapid succession then quickly changed the scope so the rifle wouldn't have time to "cool down" and fired 10 more with the other scope. I repeated that so I had two alternating groups to compare and there was a definate difference between old and new. I wonder if the Leapers could just have wear spots from so many cycles of recoil so that it won't always return to zero? one way or another I will send it back to PA. The only problem is, when I get the replacement scope, one of them will not have a rifle to go on........Might have to slip a new gun under that scope, any suggestions? was thinking of maybe a wally world Titan in .22 since the venom is the same action in .17
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Greeley Co.
Crosman 760
Crosman 1377
Crosman/Remington Airmaster 77 home tuned
Crosman Nitro venom dusk GRTIII, home tuned
Remington npss .22 home tuned
QB79 /ninja .177 Home tuned 15 fpe
QB78/ ninja .22 full valve mods 35 fpe
1st gen XS60c
Gauntlet .25 STK full tune and 4500psi CF bottle
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Nitro venom rebuild