GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: SpiralGroove on November 20, 2014, 07:09:53 PM
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Hey BAM B50/B51 Owners,
My two BAM's seem to have the best accuracy around 650 to 750 fps? Is this common? So far my BAM's are preferring CPUP & CPHP.
Please comment on your BAM B50/B51's preferred velocity for accuracy?
Thanks...........Kirk
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820ish with JSB 18.1g on mine. It is a total air hog as currently setup though, as I needed 30fpe out of it to take care of some important pesting at the time.
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Thanks toine,
It seems I'm asking a very difficult question for BAM50/51 owners :P
My concern is different. I'm getting 70 shots at 892 fps per fill right now, but if I can get supreme accuracy at 925 fps, then I will accept 55 shots per fill. Also, if I find 850 fps is the best, I will lower the regulator set-point and gladly accept more shots per fill.
I know all guns are unique, but there should be a short spread were the gun is most accurate.
Maybe the answer Motorhead gave me (2 months ago) of between 850 and 910 for field target competition is it.
Or maybe it's at 12 FPE like the Huntman was designed for........so with 10.5 CPUM that's 725 fps -> right???
What has experience taught BAM B50/51 owners???
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I think most guys that shoot 12 FPE shoot 8.4 gr. Exacts, or even 7.8 gr. Express or 7.9 gr. CPLs.... That's only the low 800s....
Bob
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In .177 found 10.3 / 10.5 weights in around 920 fps to be VERY accurate for field use able to hit walnut size POI in excess of 50 yards.
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I also wonder if one of Mac1's new air strippers would be of any benefit for your application?
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Hey John B,
Yes, so far by a little.
But the flaw in my analysis is that I've only been shooting at about 12 yards, the length of my crawl space.
What I really must do is take them out to my friends house or range and shoot at 30 to 70 yards. Whatever pellet is best at those distances would likely be best at 12 yards to.
Since you have had many BAMS's what velocity or range did you find best - if there was one?
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I've had my B51 shooting JSB 18.1gr at two different tunes, around 830fps and later at 890fps. In both cases, I suspect I was the weak link. With a 9x scope, it was good enough to hit 0.5" Mardi Gras beads 9 out of 10 times at 43 yards. Great rifle.
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my B50 was competitive in HFT at 810 fps with jsb 10.3. It also shot the 10.5 crosmans well but at 55 yards the groups were tighter with the JSB
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Late to the party (been busy) but when I put the McMaster-Carr spring in the BAM I have shot the CPUM's REALLY well and consistent at 20-30 yards doing 675 fps. Once I put the standard spring back in they shot inconsistent again.
BZ
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What's the tank size and the O.D. tube. Any help would be appreciate.
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Not to hijack , but what is the max valve porting available on them ? Can a full .25” port be done on the b50 or b51?
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Have a read through this thread on the mods I did on my B-51.... However 50 FPE in .22 cal is available with 0.172" porting....
https://www.gatewaytoairguns.org/GTA/index.php?topic=79971.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=79971.0)
Read Reply #42 where I state that a 3/16" exhaust port is the maximum and why.... larger will hit the back of the valve.... Similar problem to an MRod valve....
Bob
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Not to hijack , but what is the max valve porting available on them ? Can a full .25” port be done on the b50 or b51?
When i did my .25 cal B50 conversion "Just" got away with .200 ports in the valve body & continued that all the way to barrel.
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Just like an MRod, you can go thinner on the wall between the inside back of the valve and the front of the exhaust port.... until it fails.... Where that point is will depend on your skill and luck.... I stated 3/16" because I felt that was safe for the "average Joe".... 0.200" is "only" a 0.006" thinner wall than 3/16"....
Bob
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Have two (a .177 B50 and a .22 B51) that still get used.
(http://i157.photobucket.com/albums/t50/ribbonstone/BAM51/36e3e98c-de1c-43a1-9f93-269e1a7c7f3b.jpg) (http://s157.photobucket.com/user/ribbonstone/media/BAM51/36e3e98c-de1c-43a1-9f93-269e1a7c7f3b.jpg.html)
Generally, they come out the box poorly tuned, so a whole lot of the posts (and "The BAM 50 Book") seems to be about slowing them down to lower speeds and longer shot counts (and usually lower operating pressures).
Lot of posts here in the past (which can be found by using the "search" feature and some patientce as the search feature works kind of oddly.
Just in case you missed "The Book of BAM"". Even though it's mostly about .177's, the same directions apply to the .22 version (same direction of change with the adjustments/mods):
http://www.lebedev.com/airgun/technical_details_for_adjusting_the_bam_b50_51.pdf (http://www.lebedev.com/airgun/technical_details_for_adjusting_the_bam_b50_51.pdf)
Between the old posts and "the book", think you can get an idea about them.
Aren't bad rifles...at least for their time (were "hot snit" back about 8-11 years ago)...are kind of getting on the old side (considering the last imporation I'm aware of into the US) without a great supply of spare parts.
Eventually, decided that as they were a "pair" decided to tune them to act like a pair. So both are shooting at about 850fps average, the .177 with 16.2gr. pellets (26 foot pounds) and the .22 shooting 21gr. pellets at 850fps (33.9 foot pounds), both getting about the same number of good shots (27-30) from their moderate pressure fill (2400psi).
I still have them and shoot them, so they have passed the test of time....work as well as the newer rifles.
Bad stuff:
1. By now, it's either in need of a reseal or pretty close to it (unless you find one that someone has already resealed). For that matter, a "leaker" wasn't too unusual even when new. It's not really a super hard job to take apart and change o-rings.
2. They can break valve stem seals....they tend to smack-the-carp out of the valve stem. It is one I would NOT dry fire unless I was already sure it had a full charge.
3. The issue LDC is pretty much just a suggestion of an LDC....and the barrel is a kind of odd size.
4. Today's airgunners freak out if they don't have a gauge....it doesn't have a gauge.
5. You will get into it and tune it somewhat (as in "the book"). Better to think of them as fully finished "kit guns", as everything is there, just not quite in balance.
6. Are heavy rifles.
7. Chinese PCP barrel making of a decade ago was a bit more hit-or-miss. Good barrel is as good as any other good barrel, but were more "turds" then than now. The two above turned out to have barrels that will shoot well.
Good stuff:
8. Other than the valve stem seal, they're built like a tank. Kind of goes with #6, but considering the really "extra thick" air tube and that nearly all metal and wood, it's got to be heavy.
9. My two (knock on wood) are still running on the orginal valve stems (see #2) although they have been resealed (see #1).
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Ooops...need an add on.
Generally, once I start seeing 920-950fps, I'll swap to a heavier pellet and start my work up over.
Does seem to get counter-intuitive past a certain point, but I'll tests in sets of 4 or 5 5-shot groups. Once you get to the "middle 900's", seems to be better to compare the WORST TWO of the groups rather than the average. Seems to be a relationship between the occasional "off point" pellet (flier) and +950fps speed.
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Mine is shooting Jsb 15 grn at approx 860 fps. I took it out a few weeks ago and posted 1.6 in for a 5 shot group @ 100 yds.
I'm happy with it.
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Had my 177 tuned for around 800 fps with AA 10.3's.
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My .177 B51 was one of the first 100 imported into the country and was better finished and fitted in some ways, others not so much and then I had the breech raised with a 1/4 spacer and a belleville washer tensioned/shrouded/in shroud moderated conversion done. It is an air hog and will shoot 3/4" or less on a dead still day to 66yards which was the distance from my back porch to the fence on my old property. Shot best at 930FPS.
Basically it's retired and needs a total rebuild but it shot best with the JSB Exact Heavy in the silver topped tin with the red and white lettering, not the new red topped tin and weighed 10.2, not the 10.3 of today. Note the old tins did not even have the weight on the label, haha I bought 35 tins of 500 ea at $4.52 ea. and still have 4 left unopened.
Shot best at 930FPS
Even have thought of trying to find a good home for it with a B50/51 lover as I moved on to MUCH higher caliber n powered air rifles and have not shot .177 or .22 in probably 8 years.
Nope, on second thought, I had forgotten I bought a Chief when they came out and shot it for a month and racked it... ought to sell that one too.
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I agree with Ribbonstone that once I hit over about 970 fps with a pellet, I switch to a heavier one (if I can).... or detune the gun back to the mid 900s....
Bob