Regulator for BAM B51

[Taso1000]

Hello all,

I am looking for information on regulating a B51 in .177 caliber.  I pretty much understand what a regulator does from reading a lot on this forum but I am confused with all the different models.  I have seen mentioned regulators from Lane, Huma, Milo74 and others.  What are the design differences?  Is one design better or more efficient than another?  Why do some need the air reservoir tube drilled?  I'd rather not make permanent modifications because parts are limited for the B50.

I will either want the rifle detuned to ~6 fpe for quiet back yard target practice or at ~20 fpe with 10.5 grain pellets at ~900 fps.  Almost forgot to mention, I am pumping.  So keep that in mind.

I have also read about the valve poppet design flaw.  I think Tim McMurray's take on lightening the springs and hammer/spring guide to make the gun last longer makes a lot of sense.  How light of a hammer and spring guide is recommended?

Thanks to all in advance for your help.

Taso

[tracker1955]

I have a Bam B-50 from Mike M. I have cut 2 coils off the stock hammer spring, and a custom made from Mike delrin top hat. Also have a delrin transfer port drilled at 1/16", rifle shoots AA 10.34's in high 700's and is very quiet with the fake LDC on the barrel. I say fake, but if you take it off it is much louder so it does do something. It is almost as quiet now as my 30 fp shrouded synrod 22. Am giving this rifle to my grandsons who are 11 and 16. I should mention that it charges to 1500 psi now so will be great for hand pumping.

[GarthThomas]

I have come to the conclusion with my B50 that a couple of delrin or similar material spring guides varying in size of the stop end to change spring pre-load and the substitution of the Mcmaster Carr spring and a couple extra transfer ports starting at 1/1 6" then midway to the stock size will give plenty of adjustment for what ever power level you wish I'd also include some shim material to fine tune. As far as the dependability of the factory valve; tapering the face end and reducing the thickness of the bearing washer on the valve stem will take a lot of the stress off.
My favourite post on this rifle is this one for tuning http://www.gatewaytoairguns.org/GTA/index.php?topic=79971.msg762282#msg762282
Also if it appears in my posts that I was grovelling then that is the case, I had my rifle for almost 2 years and read all the info I could find and tried to understand it the best I could but when Rstearne started this post, it showed probably the simplest way to achieve the performance I wanted with out being a machinist, what ever parts I needed were done with a table saw and drill press.

[Taso1000]

tracker1955 and GarthThomas,

Thank you both for your responses.  I appreciate them.  Findings from people who have already experimented are awesome.  The more I research how to achieve my goals the more questions I have.  I believe it's the journey that is important.  I have to read the link you provided more thoroughly GarthThomas.  I've skimmed it twice since I've been on GTA.

I found some videos on Lane regulators that may provide me with some regulator information.  I don't know if I will benefit from them at less than 2000 psi fill pressures since I am pumping.  But we will see.

If anyone else has any tuning suggestions I'd appreciate you sharing them or pointing me to the information.

Thank you all in advance,

Taso

[anuthabubba]

At 63 y/o and short stature, I find it none too stressful to refill my 35fpe .22 B-51 to 3000psi with a Hill MkIV.

[Taso1000]

Yes sir.  I didn't say I "couldn't" do it.  I had a marauder for a couple days and pumped it up to 3000 psi a couple times with a Xisico pump.  I'd rather not on a regular basis as it wasn't enjoyable.     But I am cheap so I will pump.

Is the Hill pump easier or more efficient than the Xisico pump?  I got the Xisico pump in the FDPCP deal.

Thank you Yrok,

Taso

[nervoustrigger]

Comparing the Hill MkIII to the Xisico, the Xisico is indeed easier to pump but does not move as much air per stroke.  Consider it a tradeoff.

[Motorhead]

Have put HuMa universals custom sized to the tubes I.D. on 7-8 BAM 50/51 rifles to date.
You can use a Daystate Huntsman size regulator but it still required reducing body diameter slightly.

[SpiralGroove]

Hey Taso,
When I tuned my B50/B51, I followed Motorhead's tuning methodology and The Book as my references.
Here is what I did: .177 caliber
1) Milo74 regulator - $80 > You must drill the air tube, but no problem. Why would you ever want to go back .
2) Delrin Hammer and Spring guide.
3) McMaster Carr hammer spring per the book.
4) All ports - Barrel, Transfer and valve =9/64" or .140625
5) Replaced heavy valve spring with conical spring.
6) widened valve intake a bit.
7) Tapered factory poppet at 30 to 35 degree angle >
8 ) Vented Hammer, Spring Guide and rear of action.
9) Regulator set-point 1500 psi, gets 890/900 fps using CPUM or JSB 10.34

There was more, but I never wrote it down other than my posts ...... it's been awhile.





















It's truly amazing how much fiddling that needs to be done adjusting hammer spring tension etc. to get the most out of the gun.  I only pump too, not a problem when you get 70 shots per fill.  I would highly recommend making the RVA per Bob to get the gun shooting on the Knee of the velocity curve.  All things being said, My first full tune almost killed me - But I did learn a lot

Kirk

[toine]

Check the links in my sig for some additional B50 info.

On mine, the mcmaster spring and a lighter spring guide gets me 40 860fps or so shots with a .177 10.5g. I could and should do more to it, but for now, I am happy.

[anuthabubba]

Thanks for reposting that, Kirk.

Lately been pumping 2x 1701Ps, a 1720T, '90/'91 .177 Daystate MkI round bolt housing (heaviest of the bunch), mid '90s .22 Daystate MkII and the .22 B51 several days a week. Sometimes twice a day. Break a sweat sometimes and my elbow hurts after pumping up 2 or 3 in a row.

[Taso1000]

Thanks for the responses gentlemen! 

McMaster Carr 94125K125 springs arrived today. 

I've contacted Milo74 about a regulator. How does the Huma differ from what Milo74 offers?

I will order the tapered poppet springs today.  Edit:  I haven't been able to source these yet.  Where are you guys finding them?  Is there a comparable McMaster Carr part?  Something available through Amazon?  What has been recommended is the #83 and #86.  86 is most likely what I will need.

I've got to look at Rsterne's RVA again.  Where is the knee of the curve?  Is that were the velocities drop more abruptly for the 4% plateau we tune for?

I'm having a problem finding Delrin hammers and spring guides.  I have an email out to Mike Melick on parts availability.  Would the original hammer be hard to remove metal from the sides like in "The Book"?  I've only got a bench grinder, dremel, electric drill and table top belt/disc sander.  How light does the hammer and spring guide have to be?  Should I worry about irreversible mods since these rifles have little parts availability?

I think my first B51 will be setup like a 10 meter target rifle shooting 7.9 grain CPSM's at 500 fps.  This rifle will be shot the most in the basement and in the back yard so it has to be quiet and accurate.  I seriously considered an Air Arms T200 for this role.  But I won't learn anything or have the same pride in knowing that I tuned my B51 myself.

The 2nd B51 I am considering on getting will be tuned for 10.5 grain CPH's at 900 fps.  Hopefully quiet and accurate also.  It will fill the pest eliminator role and Field target if I can find somewhere to shoot in Illinois.  So training on the low power rifle will transfer to this one, except for the different ranges, hopefully.

I have a full tuned B26 in .177 and a full tuned B28 in .22 from Mike Melick but they're not quiet.  The power plants make more noise when they cycle than the muzzle report. 

Thank you everyone for your suggestions.  I can't wait to get all the parts here so I can start modding the rifle.  I'm positive I'll have more questions for you!   

Thank you all!

Taso


 

[SpiralGroove]

Hey Taso,
The Huma regulator ($120+), regulates better than the Milo74 and doesn't require venting in most cases.  However, Motorhead was using the Milo74 regs. in field target (IIRC), so for $80 they are fine.  Also, I don't believe Huma makes the size needed for a B50/B51, they would need to be customized (I think).
I ended up using the lighter Hillman spring in my later B51 valve as opposed to the heavier one pictured. 
Lastly, I think the Hillman #52 works as a hammer spring IIRC.

Kirk

[Taso1000]

Kirk,

Are you still using the delrin hammer?  How has it fared wear wise?  Is it much lighter than a lightened stock hammer?

Thank you,

Taso

[SpiralGroove]

Taso,
Made all my delrin hammers, spring guides, tapered poppets and other mods with my lathe.  I don't have any idea where you would buy them?
If you planning on doing a lot of work tuning air guns, buy a cheap HF 7"x12" lathe for $450 or so on sale.  Otherwise, the parts are going to cost you the price of the lathe after a couple guns.  I wouldn't even attempt to tune any airguns unless I had a lathe
I don't know how some people on the GTA do a lot of tuning with much simpler tools ......... I'm not that good.
I also don't invent any mods, I just copy the ones that make sense.

see Bob's post on tuning PCP's, and Motorhead's / The Bman's on tuning the Bam's.

My last few cents .............. Kirk

[Taso1000]

Kirk,

I'm sorry, I meant to ask, what are delrin's material properties?  I don't know if I've ever handled delrin.  I was more curious as to how it wears sliding in the receiver and engaging the sear.  It seems as it would be lighter than iron or steel.  Is it close to aluminum in weight and hardness? I was trying to weigh delrin's pro's and con's against a lightened stock steel hammer.

I don't think I'm going to look for a lathe.  I could ask my brother to keep an eye out for one.  He's an industrial engineer at a metal recycler.  But in all honesty I did think about how to turn pieces with a drill the last couple days.  ;-)  I don't think I can pull it off.  lol 

Taso

[SpiralGroove]

Yeah Taso,
I forgot to answer your 2nd to last question.
Delrin is pretty durable, but not good as 100% Nylon (this is what I believe Scott uses).  I shot about 1,000 rounds out of one of mine, when I checked the hammer, and there was a few scratches in it.  I'm sure it would last 5 to 6 times that or more, but I really don't know.  You can make 2 hammers and spring guides from 12" of 1-1/8" diameter delrin rod stock costing about $12/$15 (found on Amazon).  However, like many small parts, its all labor.  I sold a hammer and spring guide to toine a few months ago for $30, maybe he no longer needs them?

If you see Marty B post on tuning the B/51, he did all the porting, changed the valve spring to the heavier conical spring, tapered a poppet (using a drill) and IIRC used the MC hammer spring.  He kept the hammer/spring guide OEM.  He got pretty much the same results as I did with no lathe.  See his post from early 2015.
Kirk

[Taso1000]

Motorhead,

I ordered a regulator for my B51 from Milo74 today.  I was reading your post "USA manufactured PCP Regulator ( testing and discussion ) * RESULTS POSTED"  I'd like to tell Milo74 what pressure to set the regulator at.  I intend to shoot 7.9 grain Crosman Super Match wadcutters between 500 - 550 fps.   

I am getting all the parts together so I have not run the rifle in that setup to be able to read the beginning and end pressures of the velocity plateau.  I am concerned that I won't have the pressure gauge setup to accurately change it from the setting Milo74 builds it at.  He's thinking between 1200 - 1500 psi.

What do you suggest?

Thank you,

Taso

[SpiralGroove]

Taso,
It seems you need to go as low (PSI) as Milo74 can make it - 800psi or so.  If he needs to be higher, you'll just have to choke the transfer port so that less air gets to the pellet.  This way velocity can be adjusted down that low.

See what Motorhead says ..................

[MartyB]

You can do a lot with just a regulator, springs and a little fiddling.
Regulating the B50/51s fit perfectly in the 90:10 rule.  You will spend 90% of the work getting that last 10%.
Your FT goal is actually much easier than you think.  Start with the regulator and springs and see where you get.
As Kirk said, I got real close to his performance with not much more than that.  His ES and efficiency are a little better thanks to the lightweight setup.
But mine were good enough for my goals.

The 10m goal?  Personally, I wouldn't have started with a B50/51.  Too big and heavy unless you are looking to build muscle.
Dropping a Milo74 reg into a Disco is basically what I did.  Lightweight and FUN!