BAM B50 Tune!
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BAM B50 Tune!
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Topic: BAM B50 Tune! (Read 3012 times))
SpiralGroove
Ruminating Perfectionist !!!
GTA Senior Contributor
Posts: 7185
>The gun's gotta look good and shoot straight ->
Real Name: Kirk
BAM B50 Tune!
«
on:
October 19, 2014, 05:41:15 PM »
Hey fellow BAM B50/51 owners,
I have been planning to tune my B50 (.177 cal) for 3 months and finally finished all but the reassembly
1) Looking to get 70 shots at 900 fps w/ JSB 10.34's.
2) Have a Milo74 regulator w/20cc plenum, setpoint 1600 psi.
3) Did the
Motorhead
/
Bman
inspired tune except the following:
a) Widened valve TP, brass TP and barrel TP to only 9/64" or .1406", actually they're probably a touch larger.
b) Used conical valve spring and no washer on poppet, spring fits poppet nicely, but doesn't fit seat hole (using outer edge instead).
c) Used
Delrin
instead of MDS nylon on Hammer and Spring Guide.
d) Didn't install striker set-screw (lack of room w/3/8" of nose removed), plus its so tight, can barely move with small screwdriver.
e) Didn't do Pre-Load Spring mod now (can't get my head around how that works, maybe later).
I will assemble tomorrow and see how she works
Thanks.............Kirk
«
Last Edit: October 24, 2014, 01:23:28 PM by SpiralGroove
»
Logged
Bothell, WA
PCP's:
AR2079A-HPA (.177)
AR2079A-HPA (.22)
BSA R10 (.177) Huma Regulated
RAW HM1000x LRT Camo - (.20) + .177, .22 Barrels
RAW HM1000x LRT RED - (.25)
RAW HM1000x LRT Blue - (.22) + .25 Barrel
QB78 (.177) OEM
Pumper's:
1973 Benjamin Franklin 342
1984 Benjamin Franklin 347
Springer's:
Beeman R9 (.20) - Circa 2019
Beeman R10 (.20) - Circa 1988
HW30S (.177)
HW35E (2) - Blued (.177)
HW35E - Silver (.177)
HW50S - Blued (.177)
HW50S - Silver (.177)
HW80S (.20)
HW80SLK (.177) (.20)
HW95 Hybrid (HW98 stock) (.177)
SpiralGroove
Ruminating Perfectionist !!!
GTA Senior Contributor
Posts: 7185
>The gun's gotta look good and shoot straight ->
Real Name: Kirk
Re: BAM B50 Tune!
«
Reply #1 on:
October 20, 2014, 04:22:06 PM »
Hey Guys,
The air cylinder leaks badly
, I will trouble shoot tomorrow.
Here is what I think it could be:
1) The cylinder seat is pushing main spring base & hammer forward, opening the valve and allowing each pump to seemingly exit through the breach. I can see the hammer is too far forward for the trigger sear to engage it. At this point, I can't see the hammer (sear) slot through the bottom of air cylinder as it's about 1/4" forward. I believe I'm getting too much main spring tension because the MC spring doesn't fit deep enough in rear seat (holds safety).
2) Valve O-ring leak. The valve was pretty tight and the O-ring is very fragile, it could have been nicked during assembly.
3) One or both O-rings are bad on the snap piston. The whole barrel-end unit unscrewed as one piece. I didn't put in new seals/O-rings, just put it back in as before.
4) Drilled the weep hole in the wrong spot. I can see the aluminum part of the regulator so I don't think this is a problem. When installing the regulator, I almost had to pound it down (very tight).
Other than not working the gun looks great->LOL.
Tomorrow is a new day
«
Last Edit: October 24, 2014, 09:57:49 AM by SpiralGroove
»
Logged
Bothell, WA
PCP's:
AR2079A-HPA (.177)
AR2079A-HPA (.22)
BSA R10 (.177) Huma Regulated
RAW HM1000x LRT Camo - (.20) + .177, .22 Barrels
RAW HM1000x LRT RED - (.25)
RAW HM1000x LRT Blue - (.22) + .25 Barrel
QB78 (.177) OEM
Pumper's:
1973 Benjamin Franklin 342
1984 Benjamin Franklin 347
Springer's:
Beeman R9 (.20) - Circa 2019
Beeman R10 (.20) - Circa 1988
HW30S (.177)
HW35E (2) - Blued (.177)
HW35E - Silver (.177)
HW50S - Blued (.177)
HW50S - Silver (.177)
HW80S (.20)
HW80SLK (.177) (.20)
HW95 Hybrid (HW98 stock) (.177)
SpiralGroove
Ruminating Perfectionist !!!
GTA Senior Contributor
Posts: 7185
>The gun's gotta look good and shoot straight ->
Real Name: Kirk
Re: BAM B50 Tune!
«
Reply #2 on:
October 22, 2014, 03:51:19 PM »
Hi All,
Got the gun shooting today; very accurate at 13 yards (my basement) as I can hit the absolute center of a 1/4" dot pretty consistently.
Things I need to address
:
1) Velocity only seems like about 400 fps (have shortened the hammer almost as much as it will go). Weather too lousy to crony.
2) I SuperLubed the heck out of the hammer and surrounding air cylinder areas at assembly. This must be slowing down the hammer speed, so not hitting the firing needle hard enough.
3) Losing pressure due to a O-ring leak; likely the valve O-ring -> I need to buy some more of everything from Mike...
Any comments are welcomed!!!
http://i113.photobucket.com/albums/n227/kirk_schwarz/BAMB50001_zps9996613a.jpg
http://i113.photobucket.com/albums/n227/kirk_schwarz/BAMB50006_zps06bae9e8.jpg
http://i113.photobucket.com/albums/n227/kirk_schwarz/BAMB50013_zps22557dc7.jpg
http://i113.photobucket.com/albums/n227/kirk_schwarz/BAMB50011_zps080ffb87.jpg
«
Last Edit: October 24, 2014, 01:28:46 PM by SpiralGroove
»
Logged
Bothell, WA
PCP's:
AR2079A-HPA (.177)
AR2079A-HPA (.22)
BSA R10 (.177) Huma Regulated
RAW HM1000x LRT Camo - (.20) + .177, .22 Barrels
RAW HM1000x LRT RED - (.25)
RAW HM1000x LRT Blue - (.22) + .25 Barrel
QB78 (.177) OEM
Pumper's:
1973 Benjamin Franklin 342
1984 Benjamin Franklin 347
Springer's:
Beeman R9 (.20) - Circa 2019
Beeman R10 (.20) - Circa 1988
HW30S (.177)
HW35E (2) - Blued (.177)
HW35E - Silver (.177)
HW50S - Blued (.177)
HW50S - Silver (.177)
HW80S (.20)
HW80SLK (.177) (.20)
HW95 Hybrid (HW98 stock) (.177)
TheBman
Springer Fan
Sharp Shooter
Posts: 508
yes
Real Name: Brent
Re: BAM B50 Tune!
«
Reply #3 on:
October 22, 2014, 06:49:56 PM »
Nice looking rifle.
I think you are on the right track about removing the superlube.
Logged
Norman Indiana
TX200HC .177
PROSPORT .177
HW95 .177
R11 .177
HW97KT .177
HW97K .177
SpiralGroove
Ruminating Perfectionist !!!
GTA Senior Contributor
Posts: 7185
>The gun's gotta look good and shoot straight ->
Real Name: Kirk
Re: BAM B50 Tune!
«
Reply #4 on:
October 23, 2014, 03:06:12 PM »
Tune Update
,
1) Pulled hammer and spring seat out and wiped off all SuperLube.
2) Removed almost all SuperLube from air cylinder under action -> so hammer is not slowed.
3) Turned threaded striker "in" so that only about 1/16" now sticks out of hammer.
4) Velocity up to 650 fps.
5)
The gun is surprising docile
(very quiet even for 650 fps).
Continuing issues
:
1) When I pump to 200 bar there seems to be a light, cool breeze coming from rear of action (valve o-ring definitely leaking). The gun just can't hold enough pressure for the regulator to function at it's 1,600 psi setpoint.
2) Will replace Valve o-ring after rounding all (inside) stamped out edges from air cylinder under action. I lightly hit the entire air cylinder before, but when the valve o-ring expands it is pushed up into these crevices and nicked by
any
remaining edge.
For those thinking about doing this tune, it's not that hard, even though I'm bumping my head (learning) along the way. Working on a PCP is just so much different than a springer! I think once I get a new o-ring, this baby will be ready for some fine tuning. The gun has already proven to be accurate.
«
Last Edit: October 24, 2014, 01:44:24 PM by SpiralGroove
»
Logged
Bothell, WA
PCP's:
AR2079A-HPA (.177)
AR2079A-HPA (.22)
BSA R10 (.177) Huma Regulated
RAW HM1000x LRT Camo - (.20) + .177, .22 Barrels
RAW HM1000x LRT RED - (.25)
RAW HM1000x LRT Blue - (.22) + .25 Barrel
QB78 (.177) OEM
Pumper's:
1973 Benjamin Franklin 342
1984 Benjamin Franklin 347
Springer's:
Beeman R9 (.20) - Circa 2019
Beeman R10 (.20) - Circa 1988
HW30S (.177)
HW35E (2) - Blued (.177)
HW35E - Silver (.177)
HW50S - Blued (.177)
HW50S - Silver (.177)
HW80S (.20)
HW80SLK (.177) (.20)
HW95 Hybrid (HW98 stock) (.177)
Motorhead
Field Target Shooter .... Stand em up Shoot em down
GTA Senior Contributor
Posts: 17753
2019 GTA Hall Of Fame Recipient
Real Name: Scott
Re: BAM B50 Tune!
«
Reply #5 on:
October 23, 2014, 05:02:43 PM »
Those valves get installed with the valves end cap slightly loose and o-ring relaxed. Once valve is in position, pin & screws in place you tighten the end cap crushing and expanding the o-ring against the tube wall. * this takes a LONG reach screwdriver type tool. Mine is a long piece or 3/4" delrin with slot cut into one end and a piece of metal strap in cut making the blade to turn the cap.
Most likely if you had cap tight and forced valve down length of tube the o-ring got nicked on the Tube thread lead in area
Logged
Northern California ... Old Hangtown
**
Home of MOTORHEADS AG Tuning Services
**
* PM me for further contact & tuning info.
Sacramento Valley Field Target Club
#
https://sites.google.com/site/sacvalleyairgunclub/
SpiralGroove
Ruminating Perfectionist !!!
GTA Senior Contributor
Posts: 7185
>The gun's gotta look good and shoot straight ->
Real Name: Kirk
Re: BAM B50 Tune!
«
Reply #6 on:
October 23, 2014, 07:58:00 PM »
Another Update
Because the gun was leaking air, I wanted to test the rate of air loss. After about 25 shots at 650 fps, let the gun sit for about 2 hours and noticed it only took about 25 pumps to reach 200 bar. Valve opened at 160 bar, hence not leaking Cats & Dogs.
-
This told me the gun is shooting on the regulator and there had to be a basic reason for only 650 fps.
So I believed the low velocity was due to "Not enough hammer". Hence:
a) Reduced the striker so that it was about flush with the hammer nose.
b) Added a 1/8" spacer around Main Spring Seat (rear) to increase spring tension and hammer strike.
Results---------->
Wow!
I believe the gun is now shooting around 900 to 1,050 fps. It's raining in Seattle, so I can't crony.
It's also twice as loud as before, but still only about 1/2 as loud as the Hatsan AT44's.
So now, I need to replace the valve seal and adjust striker length to find the right mix for about 900 fps.
Lastly, really liking the guns weight now, probably lost a pound by replacing main spring seat, hammer and modding stock
,
now lighter than the AT44W short
.
Getting there........slowly, but surely
Hopefully, I can find a local (indoor) gun range and can get some shot strings. 70 shots at 900 fps using JSB 10.34 is the goal, unless something else is more accurate.
«
Last Edit: October 24, 2014, 01:50:35 PM by SpiralGroove
»
Logged
Bothell, WA
PCP's:
AR2079A-HPA (.177)
AR2079A-HPA (.22)
BSA R10 (.177) Huma Regulated
RAW HM1000x LRT Camo - (.20) + .177, .22 Barrels
RAW HM1000x LRT RED - (.25)
RAW HM1000x LRT Blue - (.22) + .25 Barrel
QB78 (.177) OEM
Pumper's:
1973 Benjamin Franklin 342
1984 Benjamin Franklin 347
Springer's:
Beeman R9 (.20) - Circa 2019
Beeman R10 (.20) - Circa 1988
HW30S (.177)
HW35E (2) - Blued (.177)
HW35E - Silver (.177)
HW50S - Blued (.177)
HW50S - Silver (.177)
HW80S (.20)
HW80SLK (.177) (.20)
HW95 Hybrid (HW98 stock) (.177)
SpiralGroove
Ruminating Perfectionist !!!
GTA Senior Contributor
Posts: 7185
>The gun's gotta look good and shoot straight ->
Real Name: Kirk
Re: BAM B50 Tune!
«
Reply #7 on:
October 24, 2014, 02:35:05 PM »
Another Update,
Got a Sun break so decided to crony:
1) 908.5
2) 908.9
3) 905.4
This is pretty much at my desired velocity so the next step is to get some shots strings at a range. Hoping to get 70 around 900 ish fps...........can always increase hammer length by turning out striker to reduce velocity, if needed.
Final thoughts on other mods:
1) Should have tapered/rounded forestock more, as the rifle would look less clunky.....
2) Need to round brass trigger facing more, the edges seem a little sharp on the finger. Otherwise, trigger is great.
3) Soft bedded stock around action to weep hole. This is probably not necessary for a PCP
Other than valve seal replacement and fine tuning the shot count, I hope I'm done
Kirk
«
Last Edit: October 24, 2014, 06:20:09 PM by SpiralGroove
»
Logged
Bothell, WA
PCP's:
AR2079A-HPA (.177)
AR2079A-HPA (.22)
BSA R10 (.177) Huma Regulated
RAW HM1000x LRT Camo - (.20) + .177, .22 Barrels
RAW HM1000x LRT RED - (.25)
RAW HM1000x LRT Blue - (.22) + .25 Barrel
QB78 (.177) OEM
Pumper's:
1973 Benjamin Franklin 342
1984 Benjamin Franklin 347
Springer's:
Beeman R9 (.20) - Circa 2019
Beeman R10 (.20) - Circa 1988
HW30S (.177)
HW35E (2) - Blued (.177)
HW35E - Silver (.177)
HW50S - Blued (.177)
HW50S - Silver (.177)
HW80S (.20)
HW80SLK (.177) (.20)
HW95 Hybrid (HW98 stock) (.177)
toine
Sharp Shooter
Posts: 776
yes
Real Name: Tony
Re: BAM B50 Tune!
«
Reply #8 on:
October 24, 2014, 05:26:03 PM »
May be too late now, but hopefully you've seen some of the tips bookmarked and the book/bible for the B50/51.
https://sites.google.com/site/b50tuning/
Logged
Madison, WI
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TheBman
Springer Fan
Sharp Shooter
Posts: 508
yes
Real Name: Brent
Re: BAM B50 Tune!
«
Reply #9 on:
October 25, 2014, 11:40:02 AM »
congrats on getting it shooting! Look forward to seeing your numbers across the chrony.
Logged
Norman Indiana
TX200HC .177
PROSPORT .177
HW95 .177
R11 .177
HW97KT .177
HW97K .177
farmerjoe99
N.U.A.H Marksman
GTA Senior Contributor
Posts: 2458
Real Name: Joseph
Re: BAM B50 Tune!
«
Reply #10 on:
October 25, 2014, 11:52:50 AM »
Glad you got it all figured out
I'll be watching to see how your shot string comes out.
Have you done any accuracy testing yet?
Have fun shooting
Joseph
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Alfred NY
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BAM B50 Tune!