Marauder Pistol bstaley tune farting air?

[drummerboy7816]

Just did the bstaley mod with 4 #211 o rings (the o ring sizes are confusing as most say use 113 but the 211 I got from Home Depot are a perfect fix inside the barrel of my Prod).  Greased coated them so they shouldn't be moving around .  Also added a heavier spring (.30 diameter, 1.5", 0.42) and opened the TP using a 1/8" drillbit. 

The problem I'm having is that when I tried with 3 o rings, even when HS and HT is at full CCW, when I pull he tirgger, it lets it a "farting" of air, buzzy sounding, and uses up a whole bunch of air.  It's as if the value is stuck open for longer then it should for some reason.  Switched to 4 o rings and it's better in that it doesn't happen right off the bat, however, it still happens in certain settings of HT or HS.. sometimes it happens right off the bat in the new setting, but often it happens only when I hit a lower PSI (like under 1,500).   

I'm able to get a pretty decent tune avg 21 FPE using 18g pellets for 16 shots with 6% ES, but having trouble dialing in a setting with 16FPE avg for 24 shots without it farting out sometimes.

Any idea what's happening and how to fix it?   Thanks in advance!

[Frank in Fairfield]

Just did the bstaley mod with 4 #211 o rings (the o ring sizes are confusing as most say use 113 but the 211 I got from Home Depot are a perfect fix inside the barrel of my Prod).  Greased coated them so they shouldn't be moving around .  Also added a heavier spring (.30 diameter, 1.5", 0.42) and opened the TP using a 1/8" drillbit. 

The problem I'm having is that when I tried with 3 o rings, even when HS and HT is at full CCW, when I pull he tirgger, it lets it a "farting" of air, buzzy sounding, and uses up a whole bunch of air.  It's as if the value is stuck open for longer then it should for some reason.  Switched to 4 o rings and it's better in that it doesn't happen right off the bat, however, it still happens in certain settings of HT or HS.. sometimes it happens right off the bat in the new setting, but often it happens only when I hit a lower PSI (like under 1,500).   

I'm able to get a pretty decent tune avg 21 FPE using 18g pellets for 16 shots with 6% ES, but having trouble dialing in a setting with 16FPE avg for 24 shots without it farting out sometimes.

Any idea what's happening and how to fix it?   Thanks in advance!

First, Ben, I know you are not putting the Bstaly o-rings in your barrel.
You are putting them ahead of your hammer.
With your spring and hammer fully CCW the gun should not fire.

Turn your hammer (HT) Cw until it does.

Then turn HS CW to get the speed you want.

I have the four o-ring mod on mt 1720T but the spring I use is a bit lighter than yours:

.300X.041X.5

[FuzzyGrub]

Hammer bounce.

I looked at #211 o-ring and they should not fit, larger diameter and larger cross section.  I suspect you have something different.  Do you have ID and cross-section measurements? 

[drummerboy7816]

Just did the bstaley mod with 4 #211 o rings (the o ring sizes are confusing as most say use 113 but the 211 I got from Home Depot are a perfect fix inside the barrel of my Prod).  Greased coated them so they shouldn't be moving around .  Also added a heavier spring (.30 diameter, 1.5", 0.42) and opened the TP using a 1/8" drillbit. 

The problem I'm having is that when I tried with 3 o rings, even when HS and HT is at full CCW, when I pull he tirgger, it lets it a "farting" of air, buzzy sounding, and uses up a whole bunch of air.  It's as if the value is stuck open for longer then it should for some reason.  Switched to 4 o rings and it's better in that it doesn't happen right off the bat, however, it still happens in certain settings of HT or HS.. sometimes it happens right off the bat in the new setting, but often it happens only when I hit a lower PSI (like under 1,500).   

I'm able to get a pretty decent tune avg 21 FPE using 18g pellets for 16 shots with 6% ES, but having trouble dialing in a setting with 16FPE avg for 24 shots without it farting out sometimes.

Any idea what's happening and how to fix it?   Thanks in advance!

First, Ben, I know you are not putting the Bstaly o-rings in your barrel.
You are putting them ahead of your hammer.
With your spring and hammer fully CCW the gun should not fire.

Turn your hammer (HT) Cw until it does.

Then turn HS CW to get the speed you want.

I have the four o-ring mod on mt 1720T but the spring I use is a bit lighter than yours:

.300X.041X.5

Thanks.  You're correct, i meant in front of he hammer, not in the barrel.

Interesting, I thought I read the opposite with HT and HS (ie use HT to control desired speed once minimum is reached with spring), I'll give this way a go!

[drummerboy7816]

Hammer bounce.

I looked at #211 o-ring and they should not fit, larger diameter and larger cross section.  I suspect you have something different.  Do you have ID and cross-section measurements?

Ah.. I thought bstaley in a way helps with hammer bounce? 

I thought the 211 shouldn't fit either, but the diameters in the one I bought from Home Depot looks like the 113 so I got it, and i truely cant imagine a better fitting ring.  Picture of the ring  package attached.

[FuzzyGrub]

Hammer bounce.

I looked at #211 o-ring and they should not fit, larger diameter and larger cross section.  I suspect you have something different.  Do you have ID and cross-section measurements?

Ah.. I thought bstaley in a way helps with hammer bounce? 

I thought the 211 shouldn't fit either, but the diameters in the one I bought from Home Depot looks like the 113 so I got it, and i truely cant imagine a better fitting ring.  Picture of the ring  package attached.

The physical size on the package matches the nominal for a 113 o-ring.    My guess is they are 70D but not indicated.

For your 24@16fpe tune,, what is the throw and hammer spring adjusters set to?

[nervoustrigger]

Those dimensions are precisely a -113 O-ring.  Absurd that they'd label it a 211.  That must be their part number, and what a terrible choice because it is a valid AS568 "dash" number.

But yeah, a bstaley O-ring buffer will help prevent hammer bounce when configured correctly.

[WyoMan]

A minor thread derailment...
Has anyone, besides me, removed the flange from the striker and recessed it about .030 - .050". Seems like you wouldn't need so many O-rings. Or, you could use a SSS as a slingshot setup... works exceptionally well with the drop-sear drag.
Does anyone know what happened to BStaley? He documented this o-ring mod six years ago and then dropped off the planet about a year later... nice guy, enjoyed his posts.
Okay, carry on 

Wyo

[drummerboy7816]

So I tried the starting with full CCW as suggested and turned the HT only enough to engage a shot then a tiny bit more (0.75 CW), then slowly turned up the HS with did slowly increase the velocity (maxed out at 7.5 turns), that yielded me a FPS around 600 at 2,800 PSI (using 18.13g pellets, 14.5 FPE).  Here are the results:

#   FPS   FPE   PSI
1   601   14.5   2800
2   601   14.5   
3   588   13.9   
4   592   14.1   
5   590   14.0   
6   590   14.0   
7   584   13.7   
8   586   13.8   
9   592   14.1   2500
10   586   13.8   
11   584   13.7   
12   586   13.8   
13   584   13.7   
14   586   13.8   2400
15   582   13.6   
16   582   13.6   
17   580   13.5   
18   584   13.7   2300
19   573   13.2   
20   571   13.1   
21   570   13.1   2100
22   575   13.3   
23   573   13.2   2000
24   577   13.4   
25   575   13.3   
26   567   12.9   
27   552   12.3   
28   566   12.9   
29   558   12.5   1900
30   565   12.9   
31   564   12.8   
32   562   12.7   1900
 

ES 8.7%; however, if you take out the first 2 and that one outlier, it's under 4%.  I'm wondering if a heavier spring would help bring me to an acceptable ES at 16 FPE for 3 clips.

[drummerboy7816]

I'm wondering if o ring hardness has to do with it too, mine seems decently soft and can imagine the hammer bouncing off it on low pressure.

[triggertreat]

I would recommend starting out with a few turns on the hammer spring for more consistent hammer strikes.  I would also recommend starting out in the middle of your desired fill pressure to expose the peak of the future string.  I would also start out with an empty chamber and gradually increase the flush striker CW while shooting until you start hearing a decent amount of air coming out of the muzzle end.  At that point I would refill back to mid pressure, load pellets and shoot over a chrono while adjusting the striker CW in very small increments to the point where the velocity rises to the max velocity and then begins to drop while staying very close to the middle of your desired fill pressure.  This drop in velocity will tell you that you have come off of the O-rings and need to adjust the striker CCW to get back on them.  At that point I would do a full fill and run a full string.  If you need to make velocity adjustments after reviewing the full string I would only make fine adjustments to the striker in a CCW fashion or very slight hammer spring adjustments to correct the string results.  A small change to the striker makes a big change in velocity and you want to stay within the hammer striking the O-rings and not bypassing that action and be back to just the striker striking the valve.  Hopefully that makes sense.  I would also recommend burnishing the O-rings with silicon grease to help them stay together and be more consistent.  This will help your ES results too.

[FuzzyGrub]

A minor thread derailment...
Has anyone, besides me, removed the flange from the striker and recessed it about .030 - .050". Seems like you wouldn't need so many O-rings. Or, you could use a SSS as a slingshot setup... works exceptionally well with the drop-sear drag.

Does anyone know what happened to BStaley? He documented this o-ring mod six years ago and then dropped off the planet about a year later... nice guy, enjoyed his posts.

The head of the striker is about the same thickness of a 113 o-ring.  You could remove the head and save an o-ring.  I have used a set-screw to get more hammer throw (non-BSB tune).  You loose the positive stop at full CCW, which would be problematic on a BSB tune.  ie the throw adjustment is critical and sensitive, and having a positive reference is a good thing. 

I shim my O-rings to keep the throw adjustment within one full turn from full CCW.  I use about 2/3 of a 113 o-ring thickness for the 16fpe tune, with 3 o-rings.

I haven't seen any posts from him in a very long time.  I too enjoyed his posts and comments.  Many an o-ring has been sold on ebay using his name, but not by him. 

[FuzzyGrub]

I'm wondering if o ring hardness has to do with it too, mine seems decently soft and can imagine the hammer bouncing off it on low pressure.

A soft o-ring would be 50D, and they cost more than the standard 70D.  I have tried 90D (hard) in a BSB, but had more erratic Es.  IM me your address and can toss some 113 o-rings in an envelope for you. 

You are using a spring that is probably equivalent to what I use.  I typically only open the TP to 0.110" vs the 0.125" you are using. Should just mean less adjustment on throw for same power, but more sensitive to adjustment.   I don't think that is causing the farting, but releases more air on each bounce.

My tunes are generally 3k to 2k, and don't shoot them down as low as you have.  The lower the pressure, the easier it is to open the poppet on a hammer bounce. 

[FuzzyGrub]

So I tried the starting with full CCW as suggested and turned the HT only enough to engage a shot then a tiny bit more (0.75 CW), then slowly turned up the HS with did slowly increase the velocity (maxed out at 7.5 turns), that yielded me a FPS around 600 at 2,800 PSI (using 18.13g pellets, 14.5 FPE).  Here are the results:

#   FPS   FPE   PSI
1   601   14.5   2800
2   601   14.5   
3   588   13.9   
4   592   14.1   
5   590   14.0   
6   590   14.0   
7   584   13.7   
8   586   13.8   
9   592   14.1   2500
10   586   13.8   
11   584   13.7   
12   586   13.8   
13   584   13.7   
14   586   13.8   2400
15   582   13.6   
16   582   13.6   
17   580   13.5   
18   584   13.7   2300
19   573   13.2   
20   571   13.1   
21   570   13.1   2100
22   575   13.3   
23   573   13.2   2000
24   577   13.4   
25   575   13.3   
26   567   12.9   
27   552   12.3   
28   566   12.9   
29   558   12.5   1900
30   565   12.9   
31   564   12.8   
32   562   12.7   1900
 

ES 8.7%; however, if you take out the first 2 and that one outlier, it's under 4%.  I'm wondering if a heavier spring would help bring me to an acceptable ES at 16 FPE for 3 clips.

You don't need a heavier spring.  Go to 1 turn on throw, and try again.  My guess is the sweet spot in the throw is somewhere from 1 to 1.5 T from CCW for you. 

[drummerboy7816]

Thanks for all the great info and O ring offer John!  Ill PM you my address shortly.

I did actually try various turns at 25% increments (maybe I need to try smaller increments) of the HT at good PSI range (2400 - 2600) and here's what I got:

1 turn:  612 FPS, 15 FPE
1.25 turn: 642 FPS, 16.6 FPE
1.5 turn: 672 FPS, 18.2 FPE
1.75 turn: 701 FPS, 19.8 FPE
2 turn: 740 FPS, 22 FPE

I would be very happy with those numbers if I could get <4% ES and no hammer bounce farting.. but I found that even at 1 turn, I was starting to notice a bit farting and progressively worse with more CW turns.  The highest turns without any farting was at 0.75 turns, which is when I ran the full string above, but obviously less than ideal FPS.  Wondering if it's really the o rings being too soft (the package doesn't indicate hardness).

[drummerboy7816]

I'm wondering if o ring hardness has to do with it too, mine seems decently soft and can imagine the hammer bouncing off it on low pressure.

A soft o-ring would be 50D, and they cost more than the standard 70D.  I have tried 90D (hard) in a BSB, but had more erratic Es.  IM me your address and can toss some 113 o-rings in an envelope for you. 

You are using a spring that is probably equivalent to what I use.  I typically only open the TP to 0.110" vs the 0.125" you are using. Should just mean less adjustment on throw for same power, but more sensitive to adjustment.   I don't think that is causing the farting, but releases more air on each bounce.

My tunes are generally 3k to 2k, and don't shoot them down as low as you have.  The lower the pressure, the easier it is to open the poppet on a hammer bounce.

I did order a 0.105 TP from Hillairguns yesterday too just to have for lower tunes which sounds like is what I want to use for a 16 FPE 24 string over my current 0.125 TP?

[Ribbonstone]

Why some act like that and others don't...just is.

See your issue...it's not that you haven't found a no bonce/no fart setting,  but that you don't like the energy when it's not bouncing.

[drummerboy7816]

Why some act like that and others don't...just is.

See your issue...it's not that you haven't found a no bonce/no fart setting,  but that you don't like the energy when it's not bouncing.

Why some act like that and others don't...just is.

See your issue...it's not that you haven't found a no bonce/no fart setting,  but that you don't like the energy when it's not bouncing.

Right, I would be pretty happy with the ES of the 32 shot string (minus the outlier which could be just &^^& pellet) if that was at 16 FPE even at 24 shots.

In reading the original Bstaley long notes, and I think it's what Keith above was saying, I'm going to try the route of finding the HT sweet spot at a lower spring tension first and making micro adjusting from there using the HT for velocity (oppose to me maxing out on HS and barely any HT).  I looked at an older string I had and I think this is a good place to start, which is using HT and HS at 3.5 from CCW.  If you shave off the last 3 shots (and possibly replace with higher PSI starting at 3000 instead of 2800), it's at 3.2% ES.  Thinking turning HT a quarter or half turn more would get me to around 16 PTE goal (fingers crossed no farting).

#   FPS   FPE   PSI
1   588   13.9   2800
2   594   14.2   
3   592   14.1   
4   599   14.4   
5   601   14.5   
6   601   14.5   
7   605   14.7   
8   603   14.6   2400
9   603   14.6   
10   605   14.7   
11   605   14.7   2200
12   603   14.6   
13   601   14.5   
14   599   14.4   
15   599   14.4   2000
16   601   14.5   
17   599   14.4   
18   586   13.8   
19   599   14.4   
20   588   13.9   
21   586   13.8   1700
22   567   13.0   
23   567   13.0   
24   561   12.7   



 

[Ribbonstone]

Don't know...never was happy with the o-ring mod in the P-Rod...and I don't give up easy.  Remember trying that mod on maybe 5 or 6 airguns (mostly crosmans) and finding a couple that just didn't want to get with it...figured my P-Rod was one of "those".

Wish you better luck....not just getting it where you want it, but having it stay there.

Know that as-issued, have tuend it several ways, and could find 24 shots inside of 4%.  Some times it was as low as 14.3foot pounds, sometimes as high as 15.3 foot pounds.  Could certainly make it shoot faster/more energy, but always ended up kind of "balanced" at the same energy level in order to get 24 shots.

Considering the mags hold 8 and this gets mostly used out in the woods, figure having the shot count stop in multiples of mag. size ( made sense to me.  So 16, 24, or 32 shots seemed like good places to tune for.

[drummerboy7816]

Thanks.  It's a good thing I do enjoy the scientific process   I bought some vibra-tite to toughen up the adjustments, hopefully that'll keep it in tune once I get the settings sorted out.  My goal is to have it set up 20 PFE for 16 shots, 16 FPE 24 shots, and some absurd shot count for like 10-12FPE plinking, just by adjusting the HT and all under 4% ES.  That would be success for me.