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All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Rivers3Plinker on March 29, 2016, 11:21:22 AM
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I've begun a two phase project with the goal of increasing FPE as well as shot count on my Discovery.
The shot count will be helped by a SSG which I'll be working on later.
I have a BNM breach on this gun along with a 2260 barrel and a couple barrel bands from BNM.
I drilled the exhaust port in the valve body to 5/32 at 20 degree angle using my drill press and a simple DIY angle gauge block in my drill press vice. That seemed to work out fine, but of course the resulting hole is oval or ellipse shaped and not round. I measured my transfer port bushing from BNM and it was under 5/32 so I carefully drilled that out as well. No pics but I'm satisfied with the concentric results considering the limited tools I have to do it.
When I mock up the valve in the tube with screws and install the crosman seal over the port, I note some overhang of the seal at the back side of the port. This is due to the 20 degree angle drilling. I am debating filling this area with some JB weld and blending it into the exhaust port to eliminate this ridge. I would say it's maybe .015 or so. Does anyone think this would hold or will it simply be blasted out of the port and fired down my barrel eventually? Not sure if anyone has tried this.
Second question is I opened the throat to 15/64 again with satisfactory results as far as staying centered in the bore. However that also changes the profile of the throat edge where the poppet seals to it. The air now has to make a sharper turn into the throat because making throat larger makes it thinner and the new bore is straight out into the valve. I wanted to blend this turn. I tried to work this area with an abrasive rubber dremel bit I shaped for this purpose on my sander. Seemed to work OK. I then lapped the sealing surface using the poppet and some polishing compound with my cordless drill so it won't leak after assembly here. I think this will be ok and only other aspect I don't like is a ridge inside the chamber left by the end of the drill bit. I tried to blend that too but I'm not overly pleased with the results. It's just too difficult to access it with anything. There's also sharp ridges in the chamber from the retaining screw holes which I took to 10-32. I have no easy way to work those and clean it up.
What are others using to do this kind of work? It's so small and in such a tight area it's hard to see what you're doing and easy to make mistakes that render the valve body junk. I have another valve body on the way from Crosman so I can take another poke at this.
Thanks for replies
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I use a small set of diamond burrs for fine shaping operations, forming radii to ease airflow, etc. 1/8" shanks can be used in a Dremel or handheld drill. Even a cheap $10 set from Amazon or Harbor Freight will give a lot of mileage on soft materials like brass and aluminum, even occasional unhardened steel like a barrel or bolt probe.
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@ Steve:
With 600 posts you probably already know about ice machine tubing, but FWIW,
Ice machine water tubing is .25 dia. and fits in the transfer port.
It is a popular TP alternative.
You can cut and shape it easily.
And its cheap.
I found the top of my Disco TP seal meets with the curvature of the outer bottom of the barrel.
So using a flat face seal is not going to give the best seal.
I can wrap a piece of fine sand paper around the barrel and use that to shape the top sealing face of the tubing,
then cut the bottom to length, which is square, I believe.
This and a thin layer of liquid thread sealant around the TP should work.
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Thanks Guys,
I have diamond coated burrs for my rotary tool but the short shanks make it tough to get in there and still see what you're doing. Really what I've been wanting is a set with 2 inch shanks. I also need some speed control. I suppose a high-end rotary tool with foot controls, drive cable, and a smaller, hand held tool piece would be the best solution.
Yes I have the poly tubing on my 2289G with ported valve and it's a pain in the posterior to get that right. Once you do, it works though. I've made a number of them. I'm not sure it will work with BNM breach however because of the design for the bushing and the way it mounts up into the breach.
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Out of curiosity... What for levels are you shooting for.??? imho the disco valve already flows pretty massively because it's set to be used with co2 as well.... I actually have a smaller then stock port in mine .136 and making an easy 26.5 fpe with 14.3 grain cphp....
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Out of curiosity... What for levels are you shooting for.??? imho the disco valve already flows pretty massively because it's set to be used with co2 as well.... I actually have a smaller then stock port in mine .136 and making an easy 26.5 fpe with 14.3 grain cphp....
Good question. I don't have a number. My plan was to massage the valve for better flow, modify for stronger screws, fill it and start testing with a chrony. Compare numbers to stock and then start getting some shot strings. Try higher pressures up to maybe 2200 max and see what I get. My objective is to get the gun tuned well enough to be somewhat competitive with a .25 Mrod, or at least as good as I can get with a .22 disco without getting ridiculous. That would include converting to .25 caliber.
I'm shooting the JSB heavies 18.13 primarily but also the H&N Cuda match 21.14. I'm shooting out to 65 yards max today and would like to reach out a bit longer with these rounds assuming my mods help in that regard. More punch and less holdover.
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I easily get 14.4's into the 900 fps range... currently I am getting about 1.36 fpe/ci eff in the gun but even so its still LOUD! so I would imagine 18.1's wouldn't be terribly slower to be honest and may give me even better eff... so you should be able to get those 18.1's up there where you want without to many problems... getting my SSG built for the disco hopefully I can improve those numbers even further!!
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I easily get 14.4's into the 900 fps range... currently I am getting about 1.36 fpe/ci eff in the gun but even so its still LOUD! so I would imagine 18.1's wouldn't be terribly slower to be honest and may give me even better eff... so you should be able to get those 18.1's up there where you want without to many problems... getting my SSG built for the disco hopefully I can improve those numbers even further!!
I think those are good numbers for sure. I have seen similar with discos and CPHP on charts posted by Bob here along with what the other rounds shoot at. The 18.1 are slower but you get better efficiency and I like the added FPE down range. I have shot a wide variety through this gun and so far the 18.1 and H&N cuda group best and hit hardest at 50 to 60 yards for me.
Are you using an LDC? I agree it's LOUD - surprisingly so. I cannot shoot mine in my yard without the TKO on it. Eventually I plan to shroud it with kit from BNM and put the TKO on my 2289 instead. Yes the SSG....that is next. Should help with the noise and efficiency both.
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This will give you an idea of what you can do to the ports in a Disco valve....
(http://i378.photobucket.com/albums/oo221/rsterne/22%20PCP/IMG_2802.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20PCP/IMG_2802.jpg.html)
(http://i378.photobucket.com/albums/oo221/rsterne/22%20PCP/IMG_2799.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20PCP/IMG_2799.jpg.html)
The valve is quite capable of flowing enough air for over 100 FPE in .25 or .30 cal, providing you can get a hammer/spring combination to open it long enough at the 3000 psi pressure that requires.... You would need the 10-32 valve screws for safety, of course.... The valve in those pics is in my 2560, which produces 52 FPE in .25 cal at only 1900 psi (regulated)....
Bob
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Holy Wah Bob....going big or going home there.
That's beastly sized. Is that grove in the
The added spring pressure is one of my concerns. I don't want to build it so I need to stand on the bolt to cock it just so I can hit the numbers.
So If I'm sticking to .22 and wanting to stay around 900fps with 21 grain, do you have any guidelines about how much work / what work would be necessary to hit those numbers?
I am more or less taking a stab at it and trying to keep the BNM supplied transfer port bushing, crosman OEM port seal, and round barrel port. I was thinking( hoping ) the 5/32 port size should flow enough combined with angle porting of the exhaust. I guess I don't want to get so crazy that I'm fabricating anything for a transfer port bushing for the BNM breach. It's a tall breach and the transfer port bushing is a long, custom turned and sized affair to fit snug up inside the breach.
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I actually just finished my SSG setup last night for the double... Now my results my not be typical because when I first got the gun Lloyd had done extensive work on it, hogged out valve, Completely hogged out gauge block, Heavy spring and a Bstaley stack, and a .138 transferport.. he had it shooting an average of 38 shots at 26.3 fpe with 14.3gr pellets or a 1.36fpe/cuin eff on a 2k to 1300psi fill... it took me a few days to try to get it set and tweaked with a ssg to copy as closely to his power lvls to compare apples to apples...
I was FINALLY able to get close to his results by using a lighter spring in the SSG (I think its the .039 spring that bob recommended for 2200 fills in the disco..) and changing to a tiny .120 transfer port.... lol I was only able to gain 2 shots over that range with more or less the same fpe lol think it came out to 1.42fpe/cuin eff...
guess what I am trying to get at... unless your wanting to make significant more power then 30 fpe or so... you really dont need to do a lot of valve work and the stock valve and transfer port should be plenty unless your wanting to go monster power lvls ... and smaller might actually be a bit more efficient
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When you are modding a Disco, one thing to address is the tiny hole in the gauge port.... If you can't get air into the valve faster than it can get out, FPE suffers.... I use the PRod gauge port....
Bob
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When you are modding a Disco, one thing to address is the tiny hole in the gauge port.... If you can't get air into the valve faster than it can get out, FPE suffers.... I use the PRod gauge port....
Bob
Prod and Disco tubes are same internal diameter?
Do the valves interchange?
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id works... valves dont swap due to hole positions
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also center hole thru gauge block is smaller in a disco vs prod
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Yep, that's why using the PRod gauge block in a Disco will give you more power in a modded gun.... tho' not much difference in a stocker.... NOTE, you cannot use the Disco gauge adapter in a PRod gauge block because it is intended to seal against an O-ring and the threads are 3/8"-24 NF, while the PRod gauge block is 1/8" NPT.... You can, however, screw the Disco gauge directly into the PRod gauge block, or use a HP rated 1/8" NPT male to female extension....
Bob
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When you are modding a Disco, one thing to address is the tiny hole in the gauge port.... If you can't get air into the valve faster than it can get out, FPE suffers.... I use the PRod gauge port....
Bob
Thanks Bob - I followed your advice already and have the Prod gauge port , a new 1/8" NPT 4k psi gauge from McMaster and a high pressure extension for it too.
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I actually just finished my SSG setup last night for the double... Now my results my not be typical because when I first got the gun Lloyd had done extensive work on it, hogged out valve, Completely hogged out gauge block, Heavy spring and a Bstaley stack, and a .138 transferport.. he had it shooting an average of 38 shots at 26.3 fpe with 14.3gr pellets or a 1.36fpe/cuin eff on a 2k to 1300psi fill... it took me a few days to try to get it set and tweaked with a ssg to copy as closely to his power lvls to compare apples to apples...
I was FINALLY able to get close to his results by using a lighter spring in the SSG (I think its the .039 spring that bob recommended for 2200 fills in the disco..) and changing to a tiny .120 transfer port.... lol I was only able to gain 2 shots over that range with more or less the same fpe lol think it came out to 1.42fpe/cuin eff...
guess what I am trying to get at... unless your wanting to make significant more power then 30 fpe or so... you really dont need to do a lot of valve work and the stock valve and transfer port should be plenty unless your wanting to go monster power lvls ... and smaller might actually be a bit more efficient
Interesting....Thanks Mike. So your combo is a heavily modded valve but then a reduced transfer port to improve efficiency. The transfer port is the restriction, not the valve. BUT... you are shooting a 14.3 grain round and I'm looking to go with 18 or 21.
I think I'm going to start by modifying another valve body and go with mild mods to the exhaust port. Mod for the screws for safety, stick with stock port size but angle drill the port. Leave the throat alone and poppet too. Get some shot strings and experiment with fill pressures.
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When you are modding a Disco, one thing to address is the tiny hole in the gauge port.... If you can't get air into the valve faster than it can get out, FPE suffers.... I use the PRod gauge port....
Bob
Thanks Bob - I followed your advice already and have the Prod gauge port , a new 1/8" NPT 4k psi gauge from McMaster and a high pressure extension for it too.
Steve, was this the fitting you ordered?
(http://i66.tinypic.com/2u572o7.jpg)
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Yes, that is a good extension for the valve if you use a PRod gauge block....
Bob
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Yes, that is a good extension for the valve if you use a PRod gauge block....
Bob
Thanks Bob, any special way to seal the gauge to the adapter and adapter to the gauge block?
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Yes, that is a good extension for the valve if you use a PRod gauge block....
Bob
Thanks Bob, any special way to seal the gauge to the adapter and adapter to the gauge block?
That's the same one I ordered and I was simply planning on using teflon tape like any other NPT fitting. I suppose you could use the paste but I don't like the mess and figured it might get someplace I don't want it.
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I have a problem with tape and HP applications.
The two just don't seem right together.
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For tapered fittings (i.e. the T in NPT), PTFE tape works well.
In non-tapered threads, don't bother. That requires an O-ring or other type of compressible seal. A notable exception to that is the metal-to-metal seal at the bottom of (many) burst disks. That obviously requires tight tolerances, smoothness of mating surfaces, etc. which is why you want to be careful about over tightening a burst disk because it can gouge the seat and make sealing a problem in the event it ruptures and you need to replace it.
For obstinate applications, they make liquid thread sealants much like thread locker (and yes, conventional thread locker may work fine) but I like to treat those as a last resort.
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I actually just finished my SSG setup last night for the double... Now my results my not be typical because when I first got the gun Lloyd had done extensive work on it, hogged out valve, Completely hogged out gauge block, Heavy spring and a Bstaley stack, and a .138 transferport.. he had it shooting an average of 38 shots at 26.3 fpe with 14.3gr pellets or a 1.36fpe/cuin eff on a 2k to 1300psi fill... it took me a few days to try to get it set and tweaked with a ssg to copy as closely to his power lvls to compare apples to apples...
I was FINALLY able to get close to his results by using a lighter spring in the SSG (I think its the .039 spring that bob recommended for 2200 fills in the disco..) and changing to a tiny .120 transfer port.... lol I was only able to gain 2 shots over that range with more or less the same fpe lol think it came out to 1.42fpe/cuin eff...
guess what I am trying to get at... unless your wanting to make significant more power then 30 fpe or so... you really dont need to do a lot of valve work and the stock valve and transfer port should be plenty unless your wanting to go monster power lvls ... and smaller might actually be a bit more efficient
Interesting....Thanks Mike. So your combo is a heavily modded valve but then a reduced transfer port to improve efficiency. The transfer port is the restriction, not the valve. BUT... you are shooting a 14.3 grain round and I'm looking to go with 18 or 21.
I think I'm going to start by modifying another valve body and go with mild mods to the exhaust port. Mod for the screws for safety, stick with stock port size but angle drill the port. Leave the throat alone and poppet too. Get some shot strings and experiment with fill pressures.
I would bet that if did nothing but load up some 18.1 into the gun and shot another string I would get REAL close to if not over 30 fpe and probably pick up a couple shots as the 18.1 grainers tend to be more efficient FPE wise.. I unfortunately don't have any on hand to test or I would.....
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I use Teflon "Gas Fitters" tape.... the yellow one that is thicker than the white....
Bob
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I use Teflon "Gas Fitters" tape.... the yellow one that is thicker than the white....
Bob
Thats more like it.
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I bought two extra valve assemblies from Crosman just in case I damaged one or wanted a backup for a different approach. I spent an hour or so last night working on enlarging and tapping the holes for larger screws but I should have just stayed out of the garage. I trashed both of them hamfisted drilling the holes crooked in both and stripped the threads trying to tap another. I still have the OEM valve and might just put it back together as-is and forget about the idea.
Has anyone had any experience or tried this high flow valve from bakerairguns?
I've inquired about it through their site.
(https://www.bakerairguns.com/wp-content/uploads/2015/07/discover-valve.jpg)
https://www.bakerairguns.com/product/max-flow-valve-for-benjamin-discovery/ (https://www.bakerairguns.com/product/max-flow-valve-for-benjamin-discovery/)
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Well - Disco is back together these mods:
- Midly ported stock valve - exhaust port 20 degree ( approximately ) angle ground with carbide dremel bit followed up with diamond coated ball shape bit on the turn and then polished with paracord and Mothers aluminum polish. I do this by running the cord through the port and out the throat of the valve and apply mothers to the cord on top. I pull it in and out of the port using the cord like a polishing rope of sorts. It mostly takes off any sharp edges but also polishes the surface nicely
- Exhaust port diameter same as stock
- Drilled out the B&M transfer port bushing to .156. I mic'd the stock bushing and it was slightly smaller than stock but I can't recall numbers
- Contoured the poppet valve a bit rounding the sharp edges
- New gauge and riser with Prod gauge block. Gave me same pressure numbers as my Mark4 hand pump gauge and is actually a useful gauge.
- Drilled and tapped for 10-32 screws. One isn't as straight as I would like but no alignment issues or anything I see as impacted by it
- Trakar hammer spring
I put 2200 lbs in it and it sighted in at 45 yards. First few shots were about 10" higher than before hitting my trap harder and faster than I recall.
Regardless of any increase in power, which I have yet to determine is...... it groups a lot better! I was very pleased with groups.
I shot it down to 1600psi before refilling and no change in POI. I want to say 16 shots or so, but did not count.
Without pics or charts this post is kind of lame but I'm happy with my Disco for now.
Chronny testing next weekend for sure. Going to have a gun fun day with my brother and his Mrod and get numbers and shot strings for both guns. We'll also be tag team pesting starlings which should be a blast. Bringing lots of ammo and my pump.
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Very cool man! want to see what your strings are looking like now!... I would post my shot strings with the restricted transfer port but photobucket seems to be on the fritz right now lol
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I ordered and received the Boss valve from Baker Airguns and made a few observations.
Exhaust port size nearly same as stock. The port is angled and machined as a new part this way, not a straight port modified with angle drilling. The poppet is nicely profiled for air flow at the throat and made from brass and polymer. I don't have a bore gauge or any way to measure the throat easily so I didn't attempt.
My plan is to get numbers and shot strings from my DIY modified valve and then swap out for the Boss and do the same.
The outcome will likely be higher FPE peak numbers, a peakier string, and lower shot count / more rapid air consumption with the Boss valve.
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Looking forward to seeing your numbers!!!
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ROUGH day today. So we shot my brothers box stock .25 Synrod. He was getting numbers in the 750's give or take 10fps for about 30 shots and was dead-nuts accurate. At shot 31 they started POI high and left and it was making the telltale PRRRRT sound dumping air from the yo-yo effect. What a fun gun to shoot!
I was next. filled to 2200lbs and managed 6 shots all in the 850 range before "PFFFFFFT!" my gun discharged all it's air and wouldn't pump anymore. Tear down revealed the poppet head cracked and came apart! So I reassembled with my newly purchased boss valve.
It wouldn't hold pressure either! I pulled the bolt and dry fired it, tried pumping it with the bolt open and closed. I couldn't get it to take a pump no matter what I tried. Tore it all apart again, removed the Boss valve and put mine back in the gun with a new poppet. While installing my 1st gen Mrod / Challenger trigger I flipped the sear over the wrong way and while tightening the trigger group screws, I broke the dang sear. I was DONE for the the day and irritated. My numbers with my home ported valve were around 840 to 860 for the few shots I managed to chronny. What a frustrating day. I put all the parts in a bag and grabbed a beer afterwards.
I will be back. I cannot figure out why the Boss valve poppet would not seat or seal to the throat. I will probably try lapping it with compound and and use a drill to see if I can get it to seal. I'll be ordering another sear Monday.
FWIW I was nailing shots from 50yds while I was testing. It was working great with tight groups up until the poppet failed. Major bummer.
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Ouch! That not right. Hopefully it'll be something simple and a quick fix.
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Interesting read. I like the tip about using the paracord and Mother's. I'll have to remember that. Sorry about your crappy luck with the poppets...can't wait to hear some numbers when you get it fixed.
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New sear in the mail from Crosman. I put the trigger back together and while I was in there, a spring shot out of it across the room.
I found it but wasn't able to quickly identify where it was supposed to go.
After some quick Google searching, I learned it was the dreaded "lawyer spring" so I left it out.
Trigger is lighter than before now. Feels pretty good to me.
Rifle is back together and holds air. Everything looks good so far but no shots yet.
I picked up a camera tripod from Amazon for my Chrony so I'm ready to get numbers now.
We will have cool whether this weekend ( Michigan ).
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OK I finally had some time to shoot last Friday but didn't have time to play with the chronny.
What I can say is with a mildly ported stock valve, Prod gauge port, Prod hammer weight, and TRAKAR spring in the gun:
Filling to 2000psi shooting 18.1 grain JSB
- First 3 to 4 shots are much higher POI until the gun reaches 1800psi
- Settles down at that pressure and shoots quarter size groups at about 45 yards resting on the hand rail of my deck. No bag or sled or bipod.
- Averages about 12 to 14 shots grouping well until pressure reaches about 1200psi beyond which point they start dropping very fast
I guess this is an expected result based on mods and lack of SSG. I desperately need one for the gun now to increase the shot count with this valve. I "think" my FPS is in the 850 range which is where it was last time I chronographed it with this same valve using only a different poppet that had the back profiled for more flow ( until it broke ). I don't believe this was making a huge difference here.
Truth be told I now understand why it's probably best to leave the gun at stock power level with a stock valve to get the most shots and most consistent POI per fill. Otherwise I'm looking at charging it to 1800 and not even getting 2 magazines of ammo through it before I have to fill again. That is my next plan - to put the stock valve back in the gun.
I am now debating a .25 cal Marauder rather than trying to take the Disco someplace it was never designed to go.
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I am now debating a .25 cal Marauder rather than trying to take the Disco someplace it was never designed to go.
This is best choice. You then have another gun to mod.
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rather than trying to take the Disco someplace it was never designed to go.
You see I'm just the opposite.... I love the Disco, and trying to push it to ridiculous power levels.... I have managed to get over 175 FPE in 9mm with one, at 3000 psi, with the appropriate valve and safety mods.... but it's not for someone who doesn't love to tinker, or know what they are doing.... ;D
Bob
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rather than trying to take the Disco someplace it was never designed to go.
You see I'm just the opposite.... I love the Disco, and trying to push it to ridiculous power levels.... I have managed to get over 175 FPE in 9mm with one, at 3000 psi, with the appropriate valve and safety mods.... but it's not for someone who doesn't love to tinker, or know what they are doing.... ;D
Bob
Yeah see that's impressive. Is that gun single tube and you fill it with a hand pump ; )
I've had my fill of tinkering lately and I just want to shoot now.
I have a .25 cal Mrod, an extra mag, and a couple tins of JSB kings in the cart at AGD.
Have not pulled trigger yet.