The Benjamin Disco Double made by Lloyd Sikes.
This report covers:
- History
- Disco Double
- Still holding air
- The plan
- Summary
Do you like stories? Sit back and enjoy this one, because it’s good.
History
In October 2006, I attended an airgun writers’ conference at Crosman’s plant in New York. I think there were four of us. They called us together to see their new products for 2007 and to ask what things we thought they should make in the future. I had been nursing the idea for a unique type of American-made precharged pneumatic (PCP) rifle and decided that Crosman was the only company who could make it.
I learned at that conference they were interested in starting a line of PCPs, but when I mentioned the idea I was poo-pooed by the other writers. They said the UK, Sweden and the Orient were the only places where PCPs could be made.
A month later I made a proposal to Crosman for an American PCP, and they liked my idea. It would be a lower-pressure PCP based on a CO2 model they already produced, lowering the development time and cost. I suggested the Benjamin AS392T as a starting point and 1,800 psi as the fill level.
Ed Schultz took my idea and converted two Crosman 2260 CO2 rifles to use air, and he went to 2000 psi. That was a better platform to convert; I just hadn’t thought of it.
Crosman was amazed that just 2000 psi would generate 1,000 f.p.s. in .177 caliber. I knew it would because of the USFT rifle Tim McMurray and Larry Durham created that was doing something similar on 1,500 psi.
Disco Double
Long story short — in 2007 the Benjamin Discovery was born and airgunning changed forever — both at Crosman and for the world in general. PCPs became less expensive and more capable.
That’s a good story, but it’s not today’s story. For that we have to fast-forward to 2013
The October, 2013 Roanoke airgun show was a poignant one for me. It was the first show in more than a decade where my buddy Mac was not with me. He passed away on May 5, 2013, and I stopped going to events for several months afterward. Roanoke was my first outing since his passing.
A man walked up to my table with a Benjamin Discovery and told me he had bought it from me the previous year. I recognized the rifle as one Mac had sold (we were both at the same table). I could see in this man’s eyes that he was very concerned!
He said the rifle now had a slow leak that needed to be repaired and he had brought it to the show to get his money back. I looked at the rifle and saw it was in fine shape. I bought it back because that’s what Mac would’ve done.
It may surprise you to learn that before this I had never owned an actual Benjamin Discovery! When Crosman and I developed the rifle in 2007, I tested two prototypes that were Discoveries in every way, but they were not production guns. They were 2260s converted to Discovery specifications. I’d helped develop the Discovery but I never actually owned one before 2013. And I had a plan for this one!
Lloyd Sikes had a table at the same show. Lloyd is the man who invented the electronic valve technology that was in the Benjamin Rogue. But Lloyd was also adding an additional air tube to Discoveries to double their air capacity. I had wanted to test something he was building, and this Benjamin Discovery with two air tubes seemed ideal! And his latest iteration of that was a special lightweight version.
I left my brand new Discovery with him to build a lightweight Disco Double. We made those decisions both at that airgun show and in emails as time passed. But the original idea of a lightweight Disco Double with dual aluminum tubes remained the core plan.
Aluminum reservoir tubes (above) are thicker, but much lighter than the conventional steel tube below.
Here’s a comparison of the original Discovery air tube (above) with the 2 aluminum air tubes of the lightweight Disco Double. The rifle’s barrel is at the top.
This is the assembled lightweight Disco Double, minus the stock. The tubes have been finished in black to match the barrel. The Discovery trigger is still attached, but was exchanged for a Marauder trigger.
A normal Disco Double had a Discovery trigger. It’s functional, but it’s certainly not fine. I had Lloyd install a Marauder trigger on my rifle. He then had to find a triggerguard because the guard on the Discovery did not fit.
Where did Lloyd get the idea for the Disco Double? He was building a special .25-caliber conversion of a Discovery for a customer, and it ran out of air very fast. The double air tubes were put there to make that big .25 workable. And, after seeing what those tubes added to the rifle, Lloyd naturally expanded his conversions to the basic .22-caliber rifle and the Disco Double was born!
Still holding air
Remember all the recent problems I’ve had with PCPs leaking? Well, this week I picked up my Disco Double after 11 years of sitting dormant and found it was still holding air! I think the lower operating pressure helps preserve the o-rings, though they will harden over time. My USFT rifle still holds, as well.
The plan
I will oil the rifle when I fill it. I will test the rifle for velocity again and compare to what it did back at the start of 2014.
I’m also thinking of lubing the barrel with SLIP 2000 Airgun Lubricant after testing the velocity and testing the velocity again. And naturally I’ll test the accuracy with the new premium pellets.
Summary
I’m resurrecting a PCP from the past that was built by one of the cleverest airgun engineers on the planet! It still works, and in this series we’re going to find out how well.
Wonder if there’s any chance Crosman start making these?
OP,
You should probably not hold your breath on that one. TCFKAC stopped making the Discovery many years ago and started making the Maximus as a cheaper alternative. Then they quit making the Maximus. Recently they have brought out the 3622, which is even cheaper. This is likely as close as they will ever get. If we are fortunate, TCFKAC will bring out the 3677.
If they make them any cheaper, they will be giving them away.
Nice thought, but that ain’t gonna happen.
That is one beautiful air rifle except for the sights. If Crosman isn’t interested I would not be surprised to see a Chinese version before long.
Deck
Deck,
That is a nice looker. Besides having the dual pressure tubes and a Challenger type trigger guard, this gal was also given a laminated stock. The sights are not really that bad with the exception of their being glowy thingys, but they do work for close range shooting. Could they be better? For sure, but I doubt Uncle Xi’s cohorts will do the sights or the air rifle justice.
B.B.
Doesn’t that make you think that Crossman should have used an aluminum air tube all along?
Have a great weekend everybody!!
-Yogi
Yogi,
That makes sense, not gonna happen.
I was also at that particular airgun show and do remember meeting Lloyd. He only lives a couple/three hours from RRHFWA. My grandson and I used to go to his home in late Fall and have a Fun Shoot with him and a couple of other fellows.
He and I used to go to the GTA Fun Shoot when it was in Kentucky. When it was moved to Arkansas, I quit going. After a couple more years, Lloyd and I drifted apart, and I have not heard from him for some time now.
A while back a company was formed to convert these. They would also convert Marauders and Marauder pistols. I do not know, but I do believe the airgun world wandered away from these and forgot all about this. The only company that has gone down this road has been Evanix. How much longer they will go here is anybody’s guess.
I am looking forward to this trip down memory lane. I am also very interested in whether there is a significant velocity increase when the bore is lubricated. That could possibly result in my purchasing some of this stuff.
If you can get your hands on a Discovery or a Maximus, I would recommend doing such. Foolishly, I let my Maximus go, but at least it is in a nice, warm climate in a casa where it is greatly appreciated.
“…I let my Maximus go, but at least it is in a nice, warm climate in a casa where it is greatly appreciated.” You betcha, amigo! And if FM for some foolish reason ever foolishly had the notion to let it go, you’d get first dibs on it.
Interesting article Tom; nice looking and obviously functional PCP – it would be great if something similar came back into the market but believe RR is right when he says the 3622 is as close to that as we’re going to get.
FM,
I do hope that your sentiment will carry over to all of your Max’s.
Definitely. FM would want them to be adopted into the right family. Don’t think Mrs. FM or daughter would have a problem with that either.
FM,
Well, the truth is Mrs. RR might have an issue, but too bad.
RidgeRunner,
I look forward to the trip down memory lane as well. I communicated with Lloyd as well but we never met in person; planned to but never completed that mission.
“I am also very interested in whether there is a significant velocity increase when the bore is lubricated.”
Don’t hold your breath! From experience the barrel/projectile lubrication Snake Oil myth has bitten me twice, you know what they say about falling for it the third time. Lead (Pb) is so slippery all by itself that lube just won’t add much if any MV; as a matter of observed fact it often slows down the projectile because it adds MASS and viscosity to the stuff that needs to move down and out of the barrel.
Sell more Snake Oil?
Not shootski.
shootski
I ain’t bought none yet. We shall see.
RidgeRunner,
I used to be way more open to the NEW and IMPROVED pitch…
That train, however, has left the station.
shootski
shootski,
LOL! I hear ya! It left a looong time ago with me.
I guess that is one of the reasons I like these “old gals”. There may be a thing or two that is indeed improved, but overall, I am not impressed.
IloveWordPress, IloveWordPress, IloveWordPress…
I was blessed to be able to meet Lloyd, Mac and B.B. in person at the 2012 Roanoke show.
Can’t help but wonder if an aftermarket regulator could be installed in a Disco nowadays to increase shot count similarly instead of a double compression tube.
Kevin,
NOOOOO!
2000 psi. Easy to fill. It still works after many years! It gets over 30 powertful shots as is.
BB
B.B.,
Understood. Only reason for wondering is because it would be easier for a Disco owner to add a regulator rather than double tubes. Happy Friday
kevin
kevin,
I wonder how many fewer shots the loss of pressure tube volume to the regulator would cost you?
My understanding is that the down regulation only becomes logical at ≈ 250+ BAR.
My single tube Discovery in .177 caliber has a long useful shot string. I cannot speak for .22 or modified to .25+ caliber Discovery airguns…but why would folks want to do that (.25+ caliber) is beyond me. My Marauder and DAQs cover that far better.
Just my take on this.
I just shot with my new DonnyFL .22-.25 SUMO on my 1st Generation .22 caliber Marauder and all that can be heard is the sound of a soap bubble popping. Not even as loud as a Mouse FART.
Enjoy your weekend and get some shooting in!
shootski
Tom,
” ” DITTOS
shootski
Tom,
Do be careful to let the barrel dry thoroughly after applying that lubricant, as it very likely has a hydrocarbon solvent. Unless you also plan to test the diesel effect…
-Ben T
BenT, B.B., and Readership,
Not to worry Ben.
There are two main reasons almost all PCP and Pump Guns are immune to self ignition of hydrocarbons.
The first, is that the shot cycle is not a compression stroke but rather a decompression that results in adiabatic cooling of the released charge. Technically the charge is not capable of self-ignition because it isn’t a homogeneous mixture of the fuel with the air; and very likely would not be of the proper fuel:air ratio.
The second reason is that: a self-ignition process of most hydrocarbons starts deflagrative at about 13 bar for temperature range of 840–1300 K. For temperatures above 960 K, a transition to a detonationlike process (DDT, secondary explosion) with strong pressure peaks can be observed. The duration of the transition from deflagration to the initiation of the DDT process decreases with increasing temperature. The self-ignition behavior of most hydrocarbons in the temperature range of 650–1300 K is a two-step self-ignition (first step: cool flame process) at lower temperatures. A very short deflagrative phase is followed by a secondary explosion. The time difference between the first pressure rise caused by the cool flame process and the DDT decreases with decreasing temperature, whereas the intensity of the cool flame process increases. This second reason IS what happens in Spring Piston powerplants because the compression happens during the shot cycle not during the Pre Charging done before the shot cycle in the PCP or Pump Up powerplants.
FOR PCP and Multi Pump owners/users: as long as a static electric spark or high heat is NOT achieved in the Pre Charging cycle there is an extremely low probability of the cool (DT) and even less of a chance of a hot process (DDT) in your pressure vessel; be it a Tank, Cylinder, Bottle, or an airgun pressure tube.
shootski
PS: ALL BETS ARE OFF when charging with an oxidizing gas other than BREATHABLE AIR.
Shootski
Your thorough explanation of compression vs decompression is assuring for trying “that lubricant” (EWL 30) in the bore of a pneumatic. It also warns not to try it in a springer if I interpret it correctly.
Deck
Decksniper,
Actually inside the bore/barrel of any airgun the air charge is in the decompression phase during the shot cycle. In a spring piston powerplant the compression phase occurs before the Transfer Port (TP) once beyond that point the air charge is in decompression pushing the projectile down the bore and out of the muzzle.
shootski
PS: now back to the Army-Navy game :^)
Shootski
Understood. I have Cardin’s books. But while the high infrared flash is quickly over in the chamber, is there enough heat left at the breech to cause ignition in the barrel?
Hoping the answer is firmly no.
My reply may be a duplicate. If so, I plead cyberspacing.
Deck
Decksniper,
This is for Spring Piston powerplants only.
My personal opinion, and that is all it is, is that an in Bore/Barrel Deflagration/Detonation is precluded by the lack of a homogeneous fuel-air mixing beyond the Transfer Port. BenT was only concerned about using the lube in the Bore and not allowing the Volatile Organic Compound (VOC) to evaporate before shooting.
My opinion is that the projectile would, additionally, be a solid barrier between the thermal spike in the compression chamber and the VOCs in the Bore and would push them out of the bore as well.
The PCPs and Single/Multi Pumps don’t have this problem at the temperatures and pressures practically achieved to date.
Keep playing Devil’s Advocate Deck; it keeps me sharp and on my toes ;^)
shootski
Shootski
Presence of a pellet or slug in the breech as a shield makes good sense too. It does make me wonder what would happen if a shooter forgot to load the projectile. This is always a bad idea for a springer anyway but it does happen especially if equipped with a magazine.
I have ordered and received a bottle of this lube. I will sneak up on using it to wipe a bore starting with low velocity springers.
Thank you.
Deck
Tom,
The longevity of your PCPs that operate on lower pressures seems to indicate that high pressure PCPs pay a price for their ability to contain such high pressures.
Siraniko
Siraniko,
That’s one good reason for not filling too high.
BB
B.B.,
And what is too high? You know it!
https://www.globaloring.com/o-ring-pressure-ratings/
https://www.globaloring.com/o-ring-groove-design/
;^)
shootski
Siraniko,
Absolutely.
But the poor design of the groove, incorrect/cheap O-Ring material choice and incorrect O-Ring replacement technique/material choice by the airgun owner is also to blame.
https://www.globaloring.com/causes-for-o-ring-failure/
The linked article provides a good start at understanding the design considerations. Your Reply indicates your intuition is spot on on the pressure issue. Note especially the chart with the pressure curves and the pressure that extrusion starts!
https://www.globaloring.com/o-ring-groove-design/
Also almost every qualified source says to lubricate your O-Rings with a silicone product and it is usually O-Ring grease.
shootski
B.B.,
The Black Nights fought long and hard but it just wasn’t the day for what many believed would be the outcome of this meeting of the fiercest rivals on the Gridiron.
Go Navy!
shootski
BB and everyone else
I believe that Koreans were making double air cylinder airguns before this one. Those Senecas, Sumatras and so on. Am I wrong?
Bill,
The Career 707 from Shin Sung had double air cylinders. Here’s a report on a 9mm version of the rifle.
https://www.pyramydair.com/blog/2010/04/the-shinsung-career-707-9mm-ultra-part-2/
BB