Novice Tune-Up on a B3-1

[hyounker]

After putting everything back together, and after my last post concerning the possible breach seal leak, I fired about 150 pellets through the rifle.  The cocking action deteriorated a little, but still better than before.  I guess I need more polishing and more moly?

After the 150 rounds, I chronied several rounds and got an average FPS of 556 with an SD of 13.  I was using the Crosman Premier Hollow Points and these values are very similar to the pre-tune values.

Then I disassembled again and added 2 bronze washers (McMaster Carr 5906K512) between the spring and the spring guide. Again, I chronied several rounds and got an average fps of 540 and an SD of 11.

Does any of this mean anything to anyone?  What should I do next?  I am thinking of installing two of the same washers in the piston.  (?)  Are these 1/8" changes of any value?

I've got a breach seal test that I will try tomorrow (thanks, Howie!!).

One mistake I made was using the Crosman HPs.  Those did not perform well in my original pre-tune testing.  I misunderstood my own notes!!!  I may try again using the pointed pellets, which performed much better pre-tune.

Any help appreciated?

[davee1]

The only thing I can think of is more spacers/washers and soaking the piston seal in a preferred oil mixture for said leather seal. You may not be able to get much more out of her until you put that QF2 spring in. Folks generally see 600~700fps after a good tuneup, like Shadow said. Maybe ~550 is all she can put out right now.

The space provided by one or two washers is not that much...the washer's purpose is more about being a bearing than it is a spacer. Use 2 washers at each end of the spring and see how that does. If you can still cock it, add more space...using more washers or some type of spacer. Space the spring up to the max and see if that gives you any gain. Now, I don't have my B3 open right now, but the way I remember it, there was a lot of room in there for spacing.

It also sounds like you are thinking that you might need more moly. Moly is good stuff, but you can get too much of it in there, so be careful. You'll know that youv'e put too much in if she starts heavily smoking with each shot. A little smoke is normal at first after a lubeup, but it should minimize after 10~20 shot cycles. The more excess lube there is, the more smoke there is and the longer it lasts. I just keep shooting to "clear her out", as long as theres no detonations happening. A little smoke is ok too.

And remember that your working with a twenty dollar airgun...so smooth as silk may not last long.

[hyounker]

Howie,

Tried your test today.  Seems like no matter what I use, the paper is torn, but it seems like the fuel hose is tearing it as it tightens around the cone.  I used tissue, one ply TP, even a lense cleaning cloth.  I get a nice smooth hole in the middle, but then tears around that, but mostly to the top.

Your opinion?  You want a picture?

[hyounker]

Dave,

I'm gonna add some more spacing as time permits.  I'll post results here.  Unfortunately, my QF2 kit has been delayed because South Summit is out of stock (they claim to have sent me an email about this when their servers were down!)  Ordered another yesterday.

About the lube.  I think the only area I will concentrate on, concerning the deteriorating cocking action, is the external parts.  Admittedly, I didn't spend much time around the cocking arm and anti-bear trap device.  Everything looks good in the receiver/compression chamber/piston area, so I don't think I have any binding there.

How tight should I turn the anti-bear trap screw (the one between the two screws)?

Thanks, again.

[70GTvert]

Just hand tool tight, don't try and crank it down, that is fairly soft metal used in these guns. I removed mine. False sense of security. All it does is prevent you from pulling the trigger when in the process of cocking. Can lead to bad habits like keeping finger on or near trigger and they can and do fail, especialy in the cheaper form found on these guns. Plus, it prevents de-cocking. In all of my guns, from my b-3's to my Cat (the Beemans don't have them!) I have defeated these for the simple ability to de-cock if needed. Plus, the real safty is between the ears.

[hyounker]

I've wondered about removing it.  I always keep my hand on the cocking lever when my other hand is loading.  Like this (Figure 3 on page 4):

http://www.partsmadeeasy.com/manuals/4110%20Air%20Pellet%20Rifle%20A1.pdf

Is that the safest way?

To remove it, just remove the screw, the spring retainer and the "sliding bar"?  Anything else to remove, replace, or plug?

Thanks.

[hyounker]

Here's where I started with the Crosman Premier Pointed, pre-tune:

Average fps: 553
SD: 4.5

Post-tune, 1/8" of spacers (washers) on the spring guide:

Average fps: 577
SD: 5.8

Post-tune, 1/8" of spacers on the spring guide and 1/8" of spacers in the piston:

Average fps: 586
SD: 4.8

blah, blah, blah. . . .

Post-tune, 1/2" of spacers on the spring guide:

Average fps:  592
SD:  3.8

At 9/16" of spacers, the rifle would not cock.  These numbers seem to indicate a linear progression.  From what I have been reading, I believe that I have max'd out this rifle with this spring.  I'm gonna soak the leather seal in silicone oil/neatsfoot oil until the new qf2 spring comes in.

Is there any other suggestions?

Thanks again to everyone for all the help!  Maybe I'll crack open the Gamo 850 this weekend!!!

[davee1]

Awesome Henry!!! That's what I call "collecting data" and positive progress!!!

And now its right here for people in the future to see. We can see that spacing of the spring causes a velocity increase. Also, as the spring gets more spacing, the standard deviation goes down, meaning that it becomes more consistent. In the end, everything you've done has got you a40fps gain in velocity , andbetter consistency than what you started out with. Thats why its so fun to tinker!!! It sometimes pays off really well.

I can hardly wait to see the results of your seal soak and new QF2 spring. I think you are definately headed into 600fps territory, and hopefully 700 plus.

[hyounker]

Had some spare time today before the playoff games so I reassembled the B3 with all the spacing in the piston instead of on the spring guide.  I had been soaking the leather seal in neatsfoot oil and silicone shock oil since my last post.  I was shooting some rounds through the chrony and was surprised to see numbers in the mid 600s.  Then, out of nowhere, I got an unusually load crack from the gun and a chrony reading of 853!!!  I tried again and everything was back to "normal" in the mid 600s.  I shot 10 rounds through the chrony, then 75 pellets trying to clear any lube that may have remained in the seal.  I chronied 30 rounds, but deleted the "unusual" sounding rounds from the string that resulted in a decrease of fps in the 400-530 fps range.

I ended up with these numbers:

Average fps:  649
SD:  8.3

This indicates an increase in fps by 100 from stock!!!    I also thought the gun's "thud" was louder than usual.  So, I moved the spacing to the spring guide again.  Here's the numbers after that:

Average fps:  639
SD:  9.0

It would appear that the soaking of the leather seal has made a big difference in the ability of this air rifle.  But, is there something this novice is not seeing in this data?  I am assuming that the louder crack that I heard (resulting in an fps of 853) is a detonation.  And the "unusual" sounding rounds that resulted in a decrease in fps is dieseling?

Should I clean the seal of all lube, or shoot until things settle down?

I'm pretty excited about seeing mid 600 numbers with the stock spring!!!

[70GTvert]

That crack was detonation. Seeing a little smoke without the crack is dieseling. A little oil burned off during the firing cycle turned your air gun into a firearm for that shot. If one was all you got, I would not mess with the leather seal. If you get shot after shot like that, it may be a little too drippy with oil. That could cause your spring to crack/break, and IF you had the synthetic seal it would be slowly eating it away. The leather seems to withstand it better. Habit forming, isn’t it?

[hyounker]

Only one loud crack (with the increase in velocity).  The dieseling is happening about every 15 shots or so.  Will this go away, or should I try to get some of the lube off the leather seal?

So, obviously, detonation is the burning of the lube in the chamber, causing higher pressures.  What is happening during dieseling?

Thanks,

[70GTvert]

Most likely not. Diesling is a lighter version of detonation, and most high power springers will do it to some degree even with a synthetic seal. Some may not think so because the smoke is so faint, but they do. A leather seal will almost always have some diesling. Nature of the beast. Unless it was so dry as to not be worth its salt as a seal. Naw, if it isn't making that crack, don't wory to much. It will tone down. But even when you get to the point where the smoke may be so faint that you can't see it, you'll probably still smell the frying bacon odor these things are known for, confirming it's still buring that oil. Speaking of oil, toss what you get in that QF2 kit if you get it one, worthless stuff.

[hyounker]

John,

Thanks for the info.  I have always smelled that "smell" so I guess I have just made improvements in the piston seal, accounting for the increase in velocity.  Lesson learned!  Is it reasonable to believe that replacing the breach seal helped by about 50 fps and the thorough soaking of the piston seal, another 50 fps?

I've heard more than once to can that oil in the kit.  I've had to order another kit from Steve Archer because South Summit was out of stock (not to mention the probs with their server).  Any idea what the average improvement in fps is with the new spring?

Thanks again.

[hyounker]

I got the qf2 kit with new spring today and started over with the cleaning and lubing.  Put some serious sandpaper to the new spring, lubed it up, and installed it into a newly lubed B3.  It was a real bear to install because the new spring was 1 3/8" longer than the old spring.  My first shot was a shocker!!  932 fps!!!  No loud crack, but a different sound from the gun.  Fired it two more times and got 853 fps and 811 fps.  Decided to dis-assemble the gun and check things out.  All looked normal, but I decided to squeeze as much lube as possible out of the leather seal.  Reassembled and fired several rounds.  Had smoke pouring out of both ends of the barrel for awhile, but gradually got better.  Things seemed more normal, though the new spring made an obvious difference in the gun.  Here's the last 50 rounds:

1       11     21     31     41
791   695   696   686   749
701   716   744   678   721
772   690   682   680   728  
813   692   691   731   697
700   695   680   683   729
829   697   680   680   663
701   690   689   679   722
703   688   683   684   694
694   684   675   684   662
809   683   684   679   698

Does all this sound normal?  Looks like it was settling down to around 680 fps.  I noticed that if I took a little longer loading the pellet, I would get a higher fps from that pellet.

Hopefully, all this is normal and I can expect this gun to settle soon.  This weekend I hope to shoot her some more at some paper to see what she can do.

Any help or comments appreciated.  A special thanks to my two smaller data collectors, Jacob and Sam!!

[davee1]

I think that looks pretty much just like mine did after I soaked the seal and used the QF2 spring. A lot of inconsistency because the fuel is not regulated yet, so you get some wild numbers, a few detonations, and heavy dieseling. It just takes a while for all the smoke to clear...each rifle is different. A little smoke will always be there, but you may not notice it. When the velocity and consistency becomes more stable...then you are there. It just takes a lot of shooting. I wonder if you kept your spacing in the spring. If not, it would probably be great to try that again, and that leather seal expansion mod. Once she's settled down, you might still be able to squeeze a little more out of her.