Pivot Washer Update

[Roadworthy]

I believe I've posted before about the ongoing saga of my Nitro Piston pivot washers.  I may just be lucky having more trouble than most.  In any case, I very carefully measured barrel thickness, fork width, and washer recess on each side of the barrel.  After meticulously adding and subtracting I concluded I needed washers of 0.058" thickness each.

That's what I made to fit and installed.  The barrel could be wiggled from side to side - not a lot, just a wee bit.  The groups were pretty large.  A wee bit of wiggle is too much.

A brass or bronze washer is a nominal 0.062" thick.  I tried a set at full thickness.  It took some doing to get them in but I got the gun reassembled.  There was no side play.  No matter how loose the pivot screw the barrel stayed in one place when put there.  The groups tightened.  Unfortunately it appeared to pull the barrel slightly off to one side.  I presume it sprung the forks just a bit.

Today's exercise was shooting for a point in between.  My newest washers are right at 0.060" thick.  The barrel can be moved up and down freely.  There is no side to side play.  The groups have tightened up nicely.  If things keep on this way I think I have finally succeeded in this phase of making my Nitro Venom into a consistent shooter.

[anuthabubba]

Good info for Nitro Venom owners.

[ejc]

Thanks for posting.  I'm going to be installing bronze washers in my Titan GP sometime next week and after reading your post, I'll first try them one or two thousandths larger than what I measure they should be and adjust from there if I need to.

E. J.

[jabrams8]

Good to know, I just picked up a .22 dusk. Thanks for posting.

[Gmman1960]

I've tuned my venom a Titan and three NPSS rifles using brass washers from the hardware store. I forget the exact size and if I remember correctly I had to mill them down a little for one of them. I just lightly scuffed both sides with 400 sandpaper to remove the flash and hold a little moly grease. So far its worked well for me

[lotsofair]

ace had the right size .058  i took my micrometer with me and no grinding     perfect fit  don't forget tread lock on the pivot bolt 

[Roadworthy]

Perhaps my situation is unique.  I use no thread lock on the pivot bolt.  It seems once everything drops into alignment and the pivot bolt is adjusted correctly it stays in the same place.  I guess now that I'm done tightening and everything is where I want it I could use some thread lock, but that would involve taking the screw out again.  NAH.

[pageyjim]

ace had the right size .058  i took my micrometer with me and no grinding     perfect fit  don't forget tread lock on the pivot bolt

Do you or anyonr else happen to know if these are the proper ones for the NP2 also?

[mobilehomer]

The I.D. and thickness are the same. The O.D. is a little larger. If you get the thrust washers you don't need to remove as much. Also, don't forget, there is a small set screw in front of the pivot bolt head that prevents it from turning.

[Roadworthy]

Outer diameter of the washers is about 3/4 " (0.75").  It needs to be reduced to about 0.68" to work with the older Crosman and Benjamin break barrels.  Thickness is a nominal 0.062", but it varies a little.  You may have to measure and play to get it to work.  My gun is happiest with 0.060" washers.  It's a matter of finding what works for your gun.

[Nate530]

Hey Roadworthy. I received your PM about making pivot washers, thanks for the response. About a week ago, I had ordered another plastic set from crosman for my NP XL1500. They came in the mail. I realize the brass, or softer metal is important cause of the contact area. I would rather have the washer wear before the barrel and steel wear. I was removing my barrel and realized it won't come off with out removing the inner bushing that goes between the barrel and the pivot screw. Is it normal to have to remove that bushing or has it become off set? I'm still hoping to get lucky on a GRS kit after the Fun Shoot in May. Ezman says he will have a few for sale. I'm going to use Moly 60 to extend the life of the plastic. I may give in and make some brass washers via your instructions, but I don't want the barrel lock effect or the forks to spread, I can see the washer is specialty tapered and the seat specialty narrowed, I hope I don't put them in backwards.

[OldFlyRod]

How long do you think brass pivot washers should last verses the plastic factory ones?

[Roadworthy]

If you're happy with the plastic ones, leave them in.  I was not concerned so much with longevity as with barrel stability.  The brass washers seem to hold the barrel more stable.  I believe that's why Gene started with them way back when.

Proper washer thickness may vary from gun to gun.  That is how I ended up playing with various thicknesses.

In answer to the initial question - I have no idea how long brass lasts compared to plastic.  I'll stick with stable, though.

[OldFlyRod]

I was just curious. The Privateer, was kind enough to give me a set of brass ones when I first tore down my gun. I had to sand them down bit to make them fit. The reason I was asking, I just tightened it up after a few months of heavy shooting. It's a little tighter than I like it but if it breaks in like it did when I installed them, it should smooth out a bit. At least that's what I'm hoping for. I have not seen any metal shaving.
I seen where one member drilled a few holes in his to help hold the lube.

[Privateer]

Rod,
Those washers came from Gene with the NP2 I bought from him.
I never installed them so passed them on.
I've had no issues with the stock washers so far and have nearly 3000 rounds through this gun.

[OldFlyRod]

Jeff, have you had to retighten them yet?

[Roadworthy]

My experience with soft metal pivot washers is that you tighten them a bit after working the barrel a few times allowing things to settle into place.

I tighten the pivot until the barrel falls with a little resistance at some points.  If you tighten until the barrel holds in any position you are putting too much pressure on the washers.  The metal will actually migrate, thinning the washers, requiring tightening again.  At some point you will run out of adjustment.  Measuring the washers will confirm they are thinner but there will be no filings.  The metal is still there, it has just reformed under pressure.

[Privateer]

Jeff, have you had to retighten them yet?

I haven't had to do anything aside from cleaned the barrel and did some work on the crown yesterday.
I checked for any side play and it's fine as is.
That's one reason I haven't tuned it yet.

[OldFlyRod]

This may be a dumb question but, will the washers being too tight effect the accuracy, given the barrel is locking in it's proper position? The scope on my NP2 is heading back to the factory, so I'm not able to test it at this time.

[Roadworthy]

Theoretically pivot tension could affect accuracy in that it is possible the alive jam can't overcome the tension precisely every time.

In reality I don't have an answer.  Due to metal migration I quit tightening mine that far.

As far as the scope - I returned one Center Point scope.  I think it cost me $12 shipping.  I won't do it again.  I replaced it with a Hawke Sport 3-9 X 40.  I like it a LOT better.