Posts Tagged ‘Benjamin Discovery’

.22-caliber Lightweight Disco Double: Part 7

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3
Part 4
Part 5
Part 6

Disco Double new stock
The Lightweight Disco Double in its new stock looks striking!

This is a third look at the Disco Double shooting at 50 yards. All I’ve managed to do so far is demonstrate the Disco Double is very consistently mediocre with the best pellets — JSB Exact Jumbo RS domes. However, the last time I was out at the range with this rifle, I finally did what the builder, Lloyd Sikes, has been telling me to do all along. He said to tighten the 6 screws on the 2 barrel bands or hangers, and this time I followed his directions. Guess what? Four of the 6 screws were loose! Imagine that! I tightened them and knew the rifle would reward me for the effort.

It was no surprise when shot the best 10-shot group ever with the rifle. Ten RS pellets went into 1.195 inches at 50 yards. But I was 3 shots into a second group when the bolt handle broke off in my hand during cocking. That ended the day for this rifle.

Disco Double new stock 50 yard group 1
Ten shots went into 1.195 inches at 50 yards. This is the tightest group this rifle has fired to this point, and all I had to do was tighten a few screws.

Disco Double new stock bolt broken
The bolt handle broke off during cocking. This isn’t common, but it can happen.

As soon as I returned home, I emailed Lloyd, who put a new bolt and handle in the mail right away. I really wanted to finish the test before leaving for the Ohio airgun show (which is this Saturday), so I disassembled the rifle. I ran into a problem getting the old bolt out, but a call to Lloyd set me on the right path and soon the job was done.

The new parts arrived the following week, and I had them in the rifle inside an hour — though another call to Lloyd was necessary. He was most helpful, and I resolved my problem with a minimum of fuss. The rifle went back together, and I was ready to return to the range.

This time, I took the opportunity to mount a new UTG 6-24X56 scope scope in place of the UTG True Hunter 3-9X40 scope I took off. Naturally, the target image was much larger with this scope, which just made my job easier.

I tried several pellets that I’ve tried before, but once more this rifle demonstrated that it likes the JSB Exact Jumbo RS pellets the best. Since the rifle had been taken apart for the bolt repair (i.e., both barrel bands had been removed), I was back at the beginning on the first group. I had the front band about where it had been before (from the screw marks in the paint), and the first group of 10 went into 1.28 inches at 50 yards. That was marginally better than the 1.317-inch group I’d gotten during the previous full test, but not quite as good as the one group I shot just before the bolt broke (1.193 inches). All the screws were tight, so now it was time to move the front barrel band.

Disco Double new stock 50 yard group 2
After the barrel bands were reinstalled but before the front band was moved, I put 10 JSB RS pellets into this 1.28-inch group at 50 yards.

Harmonics
In case you don’t understand what moving the front barrel band has to do with accuracy, it comes down to harmonics. By changing the location of where the barrel is anchored, I changed how the barrel vibrates during the shot. I did a huge 11-part test of this effect a few years ago. You can read about it here.

I moved the front barrel band backwards about a half inch and tightened the 3 screws once more. Then, I fired another group of 10 shots. This time, 10 RS pellets went into 0.816 inches. That’s pretty telling, don’t you think? Of course, I have no way of knowing if I have the barrel band adjusted perfectly — all I know is that it’s better than it was before.

Disco Double new stock 50-yard group 3
After moving the front barrel band, I put 10 RS pellet into 0.816 inches at 50 yards.

A second 10-shot group went into 1.506 inches. Oops! Was that supposed to happen? Its difficult to say, but perhaps I wasn’t concentrating while shooting this group. I simply don’t know. Stuff happens to me, just like anyone else!

Disco Double new stock 50 yard group 4
The next 10 RS pellets made this 1.506-inch group.

So I shot a third 10-shot group. This one measures 0.961 inches between centers. That’s better.

Disco Double new stock 50 yard group 5
A final 10-shot group of RS pellets went into 0.961 inches.

The results
What I can tell you now is the that Disco Double is able to put 10 pellets into less than an inch at 50 yards under ideal conditions. I’ve shown you everything that’s happened, and I could go on and continue to test this rifle until I have it shooting its best. I probably will, in fact. But the lesson is what I’ve shown you today.

The Benjamin Discovery is an inexpensive PCP that can put 10 pellets into less than one inch at 50 yards under ideal conditions. The Disco Double I am testing for you here has a lot of extra work done to it and is not as inexpensive as the basic Discovery. However, this is the air rifle I wanted. It’s small, it’s accurate, it has a wonderful trigger and this one gets a load of shots on a fill of just 2,000 psi. That’s everything I wanted in a PCP.

Best of all, this rifle weighs no more and is no larger than a standard Discovery. Despite the additional air capacity, I had to sacrifice nothing. That was the real reason I had this air rifle built. Lloyd Sikes has a wonderful thing going here. If you’re interested in what he can do for you, find him at Airgun Lab.

.22-caliber Lightweight Disco Double: Part 6

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3
Part 4
Part 5

Disco Double new stock
The Lightweight Disco Double in its new stock looks striking!

This is a second look at the Disco Double at 50 yards. On this day at the range, the wind was quiet, so it was a good day to test.

I didn’t do anything to the rifle before this test because I didn’t have any time to stop long enough to clean the bore. So, it went uncleaned. I may have promised to do certain things before the next test, but all I actually did when the time came was grab the rifle and go back to the range.

I used the same black single sandbag you saw in the Daisy model 8 test earlier this week. The Disco Double perfectly fits the long groove of that bag and feels more secure than if it was in a conventional rifle rest.

Beeman Kodiaks
The first group was made with 10 Beeman Kodiak pellets, and they were on target since I’d already zeroed this rifle at 50 yards for the earlier test. They initially stayed together, and I thought the rifle might have turned the corner. They then began to fly farther and farther apart. In the end, 10 pellets went into 1.837 inches — hardly a group worth mentioning. When I checked back to the previous test, though, I noted that this same pellet had made a group that was 2.458 inches at 50 yards; so as bad as it is, this was an improvement.

Disco Double Beeman Kodiak target
Ten Beeman Kodiaks went into 1.837 inches at 50 yards.

Okay, that wasn’t the brilliant opening I was anticipating. Even though the same pellet beat the last group by half an inch, it didn’t seem like the time to gloat. Next up were the JSB Exact Jumbo RS pellets — the most accurate pellets in the first 50-yard test.

The first group was another teaser. It looked small through the scope. It wasn’t until I measured it that I found out it went over an inch. Ten RS pellets went into 1.317 inches at 50 yards. That’s smaller than the smallest group from the previous test. There, 10 RS pellets went into 1.3418 inches at 50 yards. This group is similar, but it’s not crushingly better by any means.

Disco Double JSB E$xact RS target 1
Ten JSB Exact RS pellets went into 1.317 inches at 50 yards.

I now have 2 groups — each of which is better than the same pellet in the previous test. One is significantly better; the other is only better by a whisker. What does that mean? Rather than try to answer that question, I decided to shoot another group. Surely, this one would be conclusive!

The next 10 RS pellets went into a 1.773-inch group. That was the hands-down worst group of both days of testing for this pellet. On the same day, shooting under the same conditions with the best pellet, I got both the best and worst groups this rifle had fired to date.

Disco Double JSB Exact RS target 2
Ten JSB Exact RS pellets went into 1.773 inches at 50 yards.

I’m sure someone can make sense out of these results — but I’m not that person! After 2 days of testing at 50 yards, I had not proven anything except that I can’t make this air rifle shoot — yet!

I considered shooting some more groups; but after looking at these results, I thought this wasn’t the day. Sometimes, the bear gets you!

Future strategy
I think what I’ll do is drag the Disco Double to the range every time I go and try to shoot different pellets each time. Maybe then I’ll stumble across the magic pellet that turns this rifle into a shooter. After testing similar rifles, I’m convinced this gun can shoot — I just haven’t yet discovered how.

.22-caliber Lightweight Disco Double: Part 5

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3
Part 4

Disco Double new stock
The Lightweight Disco Double in its new stock looks striking!

Today, we’ll look at the Disco Double out at 50 yards. I used the best pellets from the 25-yard test to speed up this test. No sense going over the same ground twice.

The first pellet I tried was the JSB Exact Jumbo RS. It did the best at 25 yards, plus it’s so light, at 13.43 grains, that it gives the rifle a little extra zing.

The rifle arrived at the range filled to 2,000 psi, so I went right to work. I clicked the scope up 5 clicks in elevation to account for the greater distance and began shooting. The day was surprisingly cold — about 28 degrees F. My trigger finger had very little feeling, yet I was able to feel when stage 2 engaged on the trigger every time. That’s important on this rifle because the trigger is very light on stage 2.

There was no wind on the range, which made this a perfect day for shooting a pellet rifle. The first 10 shots went into 1.558 inches between centers. That’s not as small as many 50-yard groups you’ve seen me shoot, but let’s keep testing.

Disco Double 50-yard JSB RS group 1
This initial 10-shot, 50-yard group of JSB RS pellets measures 1.558 inches between centers. I’d hoped for something smaller.

Crosman Premiers
Next up were .22-caliber Crosman Premiers. The first 3 shots went into 2.269-inches and I stopped shooting. These pellets weren’t going to work at 50 yards.

JSB Exact, 15.89 grains
Next up were the heavier 15.89-grain JSB Exact Jumbos that looked promising at 25 yards. They produced a 10-shot group that measured 1.778 inches between centers. It was a little larger than the JSB RS pellet group at 50 yards, just as it was a 25 yards. So far, no prize.

Disco Double 50-yard JSB Exact group
This 10-shot, 50-yard group of JSB Exact pellets measures 1.778 inches between centers.

Beeman Kodiak
The last pellet I tried was the Beeman Kodiak, which just did fair at 25 yards. Here at 50 yards, they put 10 into 2.458 inches. That’s hardly accurate! I almost stopped shooting this group when I saw how the shots opened up; but I thought that after doing that with the Premiers, I ought to let one go the distance just to show you what it looked like.

Disco Double 50-yard Beeman Kodiak group
Ten Beeman Kodiak pellets went into 2.458 inches at 50 yards. Not a pellet for this rifle.

Back to the JSB Exact RS
I wasn’t finished with the testing just yet. The rifle was topped off at 2,000 psi again, and I went back to the pellet that was giving me the best results — the JSB Exact RS. The next group of 10 was the tightest of the session, at 1.318 inches between centers. I’d adjusted the scope for the Kodiaks, so this one landed below the bull.

Disco Double 50-yard JSB RS group 2
This best 10-shot group of JSB Exact RS pellets measures 1.3418 inches between centers.

I then shot 2 more 10-shot groups with the RS pellet. The first measured 1.522 inches, and the second measured 1.543 inches. When I examined the target after bringing it back from downrange, I saw a pattern. The RS pellet wasn’t giving tight groups, but they were very consistent. Out of 4 groups, the total variance was 0.24 inches — from 1.3 to 1.5 and change. That’s pretty consistent.

What do we know?
We know this Disco Double can put 10 pellets into 0.365 inches at 25 yards. And with the same pellet, we know that it opens up to about 1.5 inches when the distance is doubled. We know it was warm when the 25-yard target was shot and cold when the 50-yard targets were shot.

And that’s about the only difference — other than I did remove the TKO silencer after shooting 25 yards. I think what I will do next is the following.

1. Clean the barrel.

2. Shoot 5 groups at 25 yards with the JSB Exact RS pellet.

3. Clean the barrel again.

4. Shoot another 5 targets at 50 yards.

One last feature I want to show you is the special optional barrel band Lloyd makes for the Disco Double. It has a Picatinny rail on the bottom, allowing you to attach a bipod at just the right spot with very little extra weight added to the gun.

Disco Double barrel band
This optional barrel band has a Picatinny rail on the bottom to accept a bipod.

Disco Double on bipod
The Disco Double on its bipod. Photo provided by Lloyd Sikes.

Summary
When I originally tested the .22-caliber Benjamin Discovery rifle in 2007, it was a pre-production prototype that was made out of a Crosman 2260. I shot several approximately half-inch groups at 50 yards with Crosman Premier pellets, but they were 5-shot groups. Now, I’m shooting 10-shots groups that I know are going to be larger. I didn’t use the JSB Exact RS pellet because it didn’t exist back then.

I believe this lightweight Disco Double has more accuracy than we’ve seen to this point. I think it must be capable of shooting at least one 1-inch group out of 5 at 50 yards. So, the test continues.

.22-caliber Lightweight Disco Double: Part 4

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3

Disco Double new stock
The Lightweight Disco Double in its new stock looks striking!

Today, we’ll look at the accuracy of the Disco Double. Before that, however, I mounted a scope, a TKO airgun silencer that they call a muzzlebrake or a lead dust collector, and something I’ve never seen in print before but something I’ve used on many precharged air rifles over the years — a bolt keeper!

What’s a bolt keeper?
First, let me tell you that when I mounted the TKO silencer, it fit the barrel perfectly. There were no barrel alignment issues that I was warned about, and I checked closely. This unit is very well made and looks beautiful on the gun. The unit I’m testing is 8-1/4 inches long; and, yes, Lloyd, I checked that it indeed is a .22 caliber before mounting it. However, when the silencer is on, the top end cap does not fit.

Benjamin Discovert Disco Double TKO silencer
TKO silencer looks great on the rifle. The top plastic end cap doesn’t fit with the silencer installed.

When I shot the gun with it on the first time, I have to say I was underwhelmed. It was quite loud. A second shot confirmed this. Then, I held the rifle to my shoulder and fired a third shot. That’s when it hit me — a blast of air in the face not unlike the glaucoma test eye doctors do. The bolt was opening and discharging compressed air with each shot!

This happens a lot with precharged guns and it doesn’t matter how cheap or expensive they are. The bolt handle lifts up and air comes back through the action. On the lightweight Disco Double, it only begins to happen when the rifle is at the bottom of the power curve, which is where it was when I tested it this time.

A simple fix is to fasten a rubber band around the bolt handle to hold it closed during the shot — a bolt keeper. Once on the gun, I just leave it there. Even though it’s not needed until the end of the power curve on this rifle, I don’t want to worry about it. You can cock and load the rifle with the band in place.

Benjamin Discovert Disco Double bolt keeper
A rubber band “bolt keeper” holds the bolt handle down when it wants to flip up on the shot.

With the handle held closed in this fashion, the rifle suddenly became very quiet — as in Benjamin Marauder quiet! I now understand why shooters have been so excited about this unit. It really works!

NOTE: Due to several reader questions about this silencer, I am removing it from the rifle and returning it to Lloyd. Silencers are a very touchy subject, since owning one that will function on a firearm requires a license for each specific silencer. I don’t want to mislead any reader, so in the interest of clarity I am simply not going to use or possess this item any longer. I wrote an article on silencers that can be accessed here. If you have any questions on the subject, I recommend you read that article.

The rifle now weighs 6 lbs., 11 oz. with everything installed. That’s very light for a serious air rifle.

Scope
I mounted a UTG True Hunter 3-9X40 scope on the rifle. Since UTG packs rings with this scope, I used them, but they’re Weaver-style mounts. So, I had to use a UTG Weaver to 11mm dovetail adapter to make them fit the dovetails on the rifle’s receiver.

I’ll be shooting from a rest at 25 yards today. The range is indoors, so wind is not an issue.

Crosman Premiers
Sight-in was accomplished with .22-caliber Crosman Premiers; so after I was on the paper, I shot the first group of 10 shots at 25 yards. The hole they made is a little taller than it is wide, but it measures 0.569 inches between centers. While that’s okay for 25 yards, it isn’t great. I’d like to see something a couple tenths smaller.

Benjamin Discovert Disco Double Premier group
Premiers all went to the same place — more or less. At 0.569 inches between centers, the group could be smaller.

Beeman Kodiak
Next up were Beeman Kodiak pellets. They’re identical to the .22-caliber H&N Baracuda pellets that Lloyd tested the rifle with, and they were what I had available. They put 10 into 0.655 inches between centers. Like the Premiers, that’s not bad…but not as good as I’d hoped.

Benjamin Discovert Disco Double Beeman Kodiak group

Beeman Kodiaks opened up more, to 0.655 inches between centers. Only use them if you need a heavy pellet.

JSB Exact RS
I followed the Kodiaks with some JSB Exact Jumbo RS pellets. They’re even lighter than the Crosman Premiers, and sometimes they can be very accurate in precharged rifles. This was one of those times. Ten pellets went into 0.365 inches, which is exactly what I’d hoped for the Disco Double. This is the pellet for this rifle!

Benjamin Discovert Disco Double JSB Exact RS group
The JSB Exact RS is obviously a great pellet in the Disco Double. Ten went into 0.365 inches at 25 yards.

RWS Superdome
Nex, I tried the RWS Superdome pellet that’s always recommended. I don’t often have good luck with them, but a lot of shooters do. I stopped after just 4 shots, though, and you can tell from the lateral spread that measures 0.634 inches between centers that they weren’t going to perform.

Benjamin Discovert Disco Double RWS Superdome group
When the first 4 shots spread out like this, you might as well stop right there. RWS Superdomes went into 0.634 inches at 25 yards.

JSB Exact Jumbo
The last pellet I tested was the JSB Exact Jumbo. These are usually among the top pellets in .22-caliber precharged air rifles, so I felt they deserved a chance. The first 2 shots were on a fresh 2,000 psi fill, and I’m not sure the rifle wasn’t overfilled by a slight amount because they both landed away from the main group. Shot 9, however, was shot while the rifle was grouping well, and I have no idea why it’s above the main group. The 10-shot group measures 0.647 inches between centers, making this the second-best pellet I tested in the rifle.

Benjamin Discovert Disco Double JSB Exact Jumbo group
These 10 JSB Exact Jumbos measure 0.647 inches between centers. The first 2 shots are the holes at the right and bottom right of the main group. Then, the rest of the pellets went into the big group, except for shot 9 that went high. There is no explanation for that one. This is a pellet I would keep trying.

Filling from a hand pump
The biggest feature of the Benjamin Discovery, aside from the low price, is the fact that the maximum fill pressure is just 2,000 psi. It’s  full right where other PCPs have run out of air. And that makes the Discovery extremely easy to fill with a hand pump.

Using the Discovery factory pump, I began the fill at just under 1,000 psi and pumped until the onboard pressure gauge read 2,000. It took exactly 100 pump strokes to fill the gun; and, until the final 20, they were as easy as inflating a bicycle tire. Only when the pressure passed 1,800 psi did I notice an increase in pump handle resistance.

One tip when filling with a hand pump is to go slow. Allow time at the top and bottom of each pump stroke for the air to flow through the various stages inside. If you don’t, you just waste energy and heat up the pump unnecessarily.

Observations so far
So far, I’m thrilled by the performance of the Lightweight Disco Double. The number of shots I get on a fill is large enough for serious shooting before it’s time for a refill and the rifle’s performance leaves nothing to be desired. A glance at the onboard gauge needle, and I know the status of the fill.

When I tested the original Benjamin Discovery rifles in both calibers, the guns I used were pre-production prototypes. I shot groups under 0.6 inches with both calibers; but at that time, I was shooting only 5-shot groups. The JSB Exact RS pellet did not exist at the time of that test. So, it’ll be interesting to see what this rifle can do at 50 yards with 10 shots. Remember — this is the first Benjamin Discovery production rifle I’ve ever shot!

.22-caliber Lightweight Disco Double: Part 3

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2

Disco Double new stock
The Lightweight Disco Double in its new stock looks striking!

Okay, all joking aside — today, we’ll look at the performance of the Lightweight Double Disco that Lloyd Sikes built. Lloyd tested this exact rifle when it was still in its factory original condition, so we can compare that to the performance of the rifle after the conversion. I was pleased to see that my chronograph results and Lloyd’s are very close.

Before the conversion, the stock Benjamin Discovery accepted a fill to 2,000 psi. From that fill, the rifle got 21 shots of .22-caliber Crosman Premiers at an average 845 f.p.s., which works out to an average 22.7 foot-pounds. Lloyd did get more shots in his string, but he discounted all those that were not within 4 percent of the average velocity. That’s a subjective choice, but it’s what drives the numbers Lloyd is giving us for the factory rifle. The maximum velocity spread in this string of 21 shots was 40 f.p.s., with a low of 820 f.p.s. and a high of 860 f.p.s.

After the Lightweight Double Disco conversion, Lloyd shot the same Crosman Premier pellets on a similar 2,000 psi fill and got a string of 33 shots at an average 849 f.p.s., for a muzzle energy of 22.9 foot-pounds at the average velocity. Again, this number includes all shots that fell within 4 percent of the average velocity. The maximum variation in this string of 33 shots was 34 f.p.s., with a low of 831 f.p.s. and a high of 865 f.p.s.

The shot count made possible by the Lightweight Double Disco conversion went from 21 to 33 shots. The average velocity did increase by 4 f.p.s., but I wouldn’t concentrate on that because these numbers will change a little each time you record them. Essentially, the gun shot this pellet the same before and after the conversion — it simply got more shots after.

What did I get with Premiers?
I filled the rifle to about 2,100 psi because I wasn’t sure that my best pressure gauge agreed exactly with Lloyd’s gauge. I wanted to start in a slightly valve-locked posture and move up into the power curve as I went, and that’s exactly what happened. Here’s my shot string.

1-20     21-40      41-end
802      856          836**
822      856          832
817       852          828
826      852          825
831*     857          824
831-     855          820
833      857          816***
837      853         STOP (47 shots)
842     853
842     860+
846     853
848     855
849     848
852     848
850     842
851      848
852     840
851     843
847     838
851     839

- Slowest shot in acceptable string
+Fastest shot in string
* First gauge photo
** Second gauge photo
*** Third gauge photo

Disco Double first gauge photo
This is where the needle was just before the fifth shot in the string was fired.

Disco Double second gauge photo
This is where the needle was after 41 shots had been fired.

Disco Double third gauge photo
This is where the needle was after 47 shots.

If I accept the shots in this string starting at No. 5 and continuing through No. 41, I get 37 shots. They’ll have a maximum spread of 29 f.p.s., with a low of 831 f.p.s. and a high of 860 f.p.s. If I’m more critical and start with shot No. 8, which went 837 f.p.s., and still stop at shot 41, the total is 34 good shots, with a maximum spread of 24 f.p.s. The low in this string is 836 f.p.s. and the high is 860 f.p.s.

Do you see how this works? It’s entirely subjective. I’m deciding what to accept and what to reject. Once I start accepting shots, though, I keep on shooting until the last shot in my acceptable string has been fired. I can’t ignore any shots in that string because I won’t be able to chronograph my shots when I’m shooting in the real world, away from the chronograph.

You must pick the starting and ending points that you feel are best for what kind of shooting you want to do. That’s why a chronograph is so essential to the owner of a PCP. If I were to shoot this same string again with the exact same starting pressure, which is very difficult to control, I might get numbers that are similar but slightly different from these.

Baracuda/Beeman Kodiaks
Next we will look at the performance with .22-caliber H&N Baracuda pellets. Lloyd tested the rifle with them, but I didn’t have any .22-caliber Baracudas on hand, so I substituted the Beeman Kodiak, which is the same pellet under a different name.

With the Discovery in factory trim on a 2,000 psi fill, Lloyd got a string of 22 shots that averaged 717 f.p.s. They produced an average muzzle energy of 24.2 foot-pounds (compared to the 22.7 foot-pounds produced with Premier pellets in the factory trim). Heavier pellets will almost always produce more energy in a precharged rifle. The maximum velocity spread with the Baracuda pellet in the factory Discovery was 29 f.p.s. The low was 697 f.p.s. and the high was 726 f.p.s.

The Lightweight Disco Double conversion running on the same 2,000 psi fill with Baracudas gave a string of 38 shots that averaged 713 f.p.s. The low was 699 f.p.s. and the high was 729 f.p.s., so the spread was 30 f.p.s. The average muzzle energy was 23.9 foot-pounds.

Baracudas got more shots per fill than Premiers
With Baracudas, Lloyd got 22 shots per fill in factory trim and 38 shots with the Lightweight Disco Double conversion. In both cases, the rifle gave more shots per fill with the Baracudas than with the Premiers. My thinking is that the heavier, slower pellet holds the valve open a bit longer and is able to go to lower pressure before it falls off the power curve.

What did I get with Beeman Kodiaks on a 2,000 psi fill (refer to the first photo of the pressure gauge to see where I actually stopped the fill)?

1-20      21-40      41-end
702        712          701
699-      720          693
707        716          695
714        718          696
709       714           683
719       726           STOP (45 shots)
717       728
711        725
723       722
718       709
711        709
715       712
728+     708
728       716
712       721
716       711
717       718
719       715
724       715
718       707

- Slowest shot in string
+Fastest shot in string

While this string has fewer shots than the first one with the Premiers, there are actually more usable shots here because I learned where the needle on the gauge had to be in the first test. No air was wasted at the start of this string. I would accept everything from shot No. 1 through shot No. 41, giving me a total of 41 usable shots, with a spread of 29 f.p.s. The low was 699 f.p.s. and the high was 728 f.p.s.

I got more usable shots from Beeman Kodiaks than from Premiers, just like Lloyd did with H&N Baracudas. Our data seems to agree very closely. Lloyd’s low velocity was 699 f.p.s. and so was mine. Lloyd’s high was 729 f.p.s. and mine was 728 f.p.s. How is that for consistency? As I said, the H&N Baracuda and Beeman Kodiak are the same pellet.

Analysis thus far
The Lightweight Disco Double increases the useable shot string significantly, even though the rifle is no larger nor heavier than a factory Discovery. You can tell from a glance at the onboard pressure gauge if the rifle is still on the power curve, so there’s no need to count the shots.

All of what you have seen to this point was done with the stock Discovery striker spring (0.035″wire, 0.289″ OD, 1.99″ long , 16.5 coils) in place. But Lloyd also provided and tested a heavier striker spring (0.041″ wire, 0.300″ OD, 1.78″ long, 19 coils) that gives both the factory Discovery and the Lightweight Disco Double conversion more power.

To see what the heavier striker spring can do with Baracuda pellets in the Lightweight Disco Double, Lloyd recorded that the average velocity climbed from 713 f.p.s. to 764 f.p.s. That is an energy increase from 23.9 foot-pounds to 27.5 foot-pounds. The total number of shots dropped back from 38 to 25 shots. This shows how the Disco Double allows the power to be increased, and the total shot count to remain the same as the less powerful factory gun.

Trigger
I haven’t reported on the trigger, yet. You may recall that I had Lloyd install an optional trigger from a Benjamin Marauder. Lloyd told me in a message that it’s set for a light first stage, and then an extremely light second-stage pull. I found at first that it was so light that I pulled straight through both stages without recognizing stage 2. But when I adapted to it, it’s really not as sensitive as a 10-meter target pistol trigger. Stage 1 takes 14.4 oz. of effort; and stage 2, while recognizable, does not increase the number on the electronic scale. It’s on the order of 10 grams or less.

Summary
So far, I’m delighted with the Lightweight Disco Double. If it turns out to be accurate, it could become my go-to PCP!

.22-caliber Lightweight Disco Double: Part 2

by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1

Disco Double new stock
The Lightweight Disco Double in its new stock looks striking!

I’d planned to report on the velocity of the Lightweight Disco Double today and, as good fortune would have it, the new stock arrived yesterday! So, I installed it and took a photo for you to see. I think it looks fabulous!

This stock was made by Normand Morin who has a website at Discos R Us. The wood grain is a very striking brown tone that’s finished shiny. The inletting is perfect for my rifle, and it dropped in with a tight fit. I like it even better than the walnut stock the rifle was shipped with. If you want to dress up your Disco, take a look at what this man can do for you.

Isn’t it ironic that I reported on the $100 PCP yesterday, and today I’m looking at the Disco Double? That wasn’t planned; but since it worked out, I’m sure you’ll draw some comparisons from the contrast of the 2 rifles.

First shots
I saved these first shots just for you! This is the first time I have fired the rifle since it arrived. I figured Crosman Premier lites could do the honors since the rifle is basically a Benjamin Discovery. At this time, I have not yet installed the TKO muzzlebrake, so the sound is what you would hear from a factory Discovery.

The needle on the rifle’s built-in pressure gauge was reading just below the 2,000 psi mark, which is the edge of the green zone for air. There’s a separate green zone for CO2 on the gauge, but it doesn’t really do much because a CO2 fill never goes above the pressure of the gas at whatever temperature the gun is at when it’s filled. In other words, CO2 pressure isn’t determined by the fill — it’s determined by the ambient temperature.

Here’s the first string I fired:

Start….21-40….41-STOP
690      739          736
709      748          —
707      757          —
718      750          715
726      757         729
720      745         724
732      744         714
728      742         716
735      753          713
729      742         701
723      754        STOP
737      742
743      746
733      741
733      742
742      744
737      745
741      734
747      722
745      738

After examining the shot string, I concluded that the reservoir pressure was slightly too high when I began shooting, so I filled it to a slightly lower pressure (on the rifle’s built-in gauge) and fired 5 more times. That gave me the following velocities:

730
731
739
728
731

At the end of these 5 shots the on-board gauge read 1,900 psi. That looks like the right pressure to me.

Disco Double top of the fill
This is as high as the fill level will go for the first shot to be in the correct velocity range.

Disco Double end of fill
When the rifle falls off the power curve, this is where the needle sits.

More Disco Double features
I told you in Part 1 that this rifle has too many features to cover in just a single report. Two more of them are the stainless steel male Foster quick-disconnect fitting that’s used as a fill nipple. Lloyd has machined it into the end cap of the lower reservoir tube and covers it with a black plastic cap.

There’s also a special barrel band he can provide that has a dovetail on the bottom for the attachment of a bipod. That looks particularly handy, and I’m thinking of doing just that.

Disco Double fill nipple
The fill nipple is stainless steel and on the bottom tube.

Disco Double barrel hanger anchor
Lloyd makes this custom barrel band, which has an anchor point for a bipod on the bottom.

Analysis of the velocity numbers
Now that I have a good first string on record, let’s see what it means. These numbers seem on the low side, though I did tell Lloyd that I wanted maximum shots over anything else.

Lloyd sent me several spreadsheets with his own test velocities that I’ll now compare to mine. Then, we can select a good performance curve for the rifle.

OH, NO!!!

What did I do?
Dear readers, I just consulted the velocity spreadsheet Lloyd sent me and discovered that he was getting velocities in this rifle in the mid-800s, also using Crosman Premiers. But I saw right away what he was doing differently.

HE WAS USING .22-CALIBER PREMIERS, where I’d been shooting the much-harder-to-control .177 Premier lites. Apparently, this Disco Double is special. Not only does it get a lot of shots, it also shoots .177 pellets in the same barrel as .22 pellets!

I swear I’m telling the you the truth, just as it happened! When I made my “discovery,” I dropped a .177 Premier pellet down the muzzle of the gun and noticed it fell all the way down.

Yes, friends, B.B. Pelletier has done it once again. I’ll now give you 5 minutes to draw a crowd for my public humiliation.

I didn’t plan for this report to go this way, but I can’t write stuff this funny when I try. So, have a great weekend at my expense, and on Monday I’ll return with some different velocity numbers. These will be obtained with the .22-caliber Premiers that probably work much better in this gun.

.22-caliber Lightweight Disco Double: Part 1

by Tom Gaylord, a.k.a. B.B. Pelletier

You tell me that you enjoy the longer reports that pick apart certain guns and analyze them in great depth. You insist that I explain the technical terms and sometimes also the terms that are specific to shooting. We have a wide spectrum of reader experience in the shooting sports on this blog; so when I write about something, I have to keep that foremost in mind. I try not to jargonize or use insider language, although I’m sure that I do from time to time.

Today we begin what will undoubtedly become a huge report. I think you will enjoy it, but I am asking for your help in managing the questions and comments that will undoubtedly result. So, sit back and pour a fresh cup of coffee or tea, for I think this trip is going to be fun for all of us!

The detailed photos in today’s report are provided by Lloyd Sikes. My thanks to him for all his work.

The 2013 Roanoke airgun show was a poignant one for me. It was the first airgun 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.

I’ve already reported on the show and don’t need to go over that ground again, but one thing that happened there does need to be mentioned. While I was at my table, a man walked up with a Benjamin Discovery in his hand 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), and I mentioned that to him. I could see in his eyes, however, that he was very concerned with the status of this gun right now!

He had shot the gun for about a year but really hadn’t used it that much. He said that it now had a slow leak that needed to be repaired and had brought it to the show to get his money back. I looked at the rifle and saw that it was in fine shape, and he had the hand pump that came with it but not the box. I fully intended to buy it back from him just because that’s what Mac would’ve done. So, we struck a deal, and the Discovery became mine.

Benjamin Discovery
I bought back Mac’s Benjamin Discovery at the Roanoke airgun show.

It may surprise you to learn that I have never owned an actual Benjamin Discovery! When Crosman and I were developing the rifle in 2007, I tested two prototypes that were Discoveries in every way, but they were not production guns. They were Crosman 2260s that were converted to Discovery specifications. I’d helped develop the Discovery 6 years earlier, but I never actually owned one before now. And, I had a plan for this one!

At the same show, Lloyd Sikes, the owner of Airgun Lab, was set up on the other side of the room. For those of you who don’t know him, Lloyd is the man who invented the technology that became the Benjamin Rogue. But Lloyd is now taking Benjamin Discoveries and adding an additional air tube to double their air reservoir capacity. Mostly, he sells kits of parts to people who want to do the work themselves — it’s easy enough for most people. But he’s also building a few very special rifles from the ground up. For over a year, I’d wanted to test something Lloyd was building, and this Benjamin Discovery seemed the ideal subject!

I walked over to Lloyd’s table and had a chat with him. As fate would have it, he was working on something brand new. He had just started experimenting with what he calls a Disco Double with both reservoir tubes made from aluminum rather than steel. The result is a gun that is nearly as light as the original Benjamin Discovery! When I picked up the prototype gun he had on his table, I couldn’t believe it. It was so light! I wanted one just like it.

Lloyd and I had several conversations at the show, and I left my brand new Discovery with him to build a lightweight Disco Double. I learned that what Lloyd makes is not just one simple product. There are so many changes that can be made in the process of modifying the rifle that a lot of decisions have to be made. 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.

When I returned from the SHOT show last week and my mail was delivered, there was a box from Lloyd! My lightweight Disco Double had arrived!

This report is going to be about the Disco Double that Lloyd built for me. If you want to know more about the basic Benjamin Discovery air rifle, read these reports.

The rifle
The Benjamin Discovery is a basic precharged pneumatic air rifle that was built to sell at a very low price. The original concept was that the gun would come packaged with a high-pressure hand pump; and because the gun had a maximum fill pressure of 2000 psi, the hand pump would be very easy to operate. When I tested the preproduction guns in both .177 and .22 calibers, each was able to produce 10-shot groups smaller than 1 inch at 50 yards. At the Discovery’s low price, this was incredible performance.

Mac had purchased one of the original 4000 rifles that were made during the first year of production. These are unique because they have genuine walnut stocks that had been made for a special 2260 rifle that was never built. After the supply of these walnut stocks was exhausted, the company changed to beech wood, which is in keeping with the low cost of the gun.

The Disco Double lighweight
The rifle Lloyd built for me has two aluminum air reservoir tubes. In conventional Disco Double conversions, the kit contains either one chrome moly steel or one high-strength aluminum tube that gets added to the rifle’s existing steel tube for greater air capacity, but Lloyd made my rifle with dual aluminum tubes — the first of its type! The No. 1 purpose of this design is weight reduction, and secondarily it increases the air capacity for more shots.

The original base rifle in factory trim weighed 5 lbs., 7 oz. The original air capacity was 130cc. The rifle as now modified weighs 5 lbs., 8 oz. and has an air capacity of 199cc. That’s 53 percent more air. The air capacity has not doubled because the aluminum tube wall thickness is greater (than steel) to provide the necessary strength. So, the tradeoff with this conversion is lighter weight (than an all-steel conversion) for a little less total air, though the air capacity is still boosted greatly.

Benjamin Discovery Disco Double tube comparison
The steel tube (bottom) has thinner walls than the aluminum tube, yet the aluminum tube is still lighter.

Benjamin Discovery Disco Double assembly comparison
Here’s a comparison of the original Discovery air tube assembly (above) with the 2 aluminum air tubes of the lightweight Disco Double. The rifle’s barrel is at the top.

Benjamin Discovery Disco Double lightweight assembly
This is the completed lightweight Disco Double, minus the stock. The tubes have been finished in black to match the barrel. The original Discovery trigger is still attached to this rifle, but will be exchanged for a Marauder trigger.

I want to point out that Lloyd is building his guns with a safety reserve of well over 4 to 1. In other words, the guns are rated for well above 4 times the air pressure at which they’re working. Well above!

Trigger
A normal Disco Double will have a Discovery trigger. Perhaps you’ve read about this trigger in your research on the internet. It’s functional, but it’s certainly not a fine trigger. I can use it without any problems; but if I had my choice, I’d like something better. Well, this time, I did have a choice; so I had Lloyd install a Marauder trigger on the rifle he made. He then had to find a triggerguard because the guard on the Discovery would not have worked.

Testing
Lloyd did an enormous amount of testing of my gun since it was the first of its kind to be built. And he has supplied me with the test data, so I have at my fingertips a whole library of velocities, pellets, fill pressures and some other things I will mention in a moment. If only all the guns I reported on had this kind of data at the start! But Lloyd is a very careful engineer, and I’ve come to know that he documents his work quite well.

Interesting background
Where did Lloyd get the idea for the Disco Double? Is the Benjamin Discovery somehow deficient in air capacity? Not really. But Lloyd was building a special .25-caliber conversion of the rifle for a customer, and it ran out of air very fast. The double air tubes were put there to make that big .25 a workable solution. And, after seeing what those tubes added to the rifle, Lloyd naturally expanded his conversions to the basic rifle, and the Disco Double was born!

The main goals of Lloyd’s kit are:

1. Safely add additional air capacity for more shots.

2. Restore the shot count after making power increases.

3. Maintain the light weight of the Discovery.

4. Provide a kit that can be installed by any airgunner who routinely works on his own airguns.

My rifle
Lloyd and I agreed that it would be best to be able to preserve the original rifle, so if I ever wanted to put it back the way it came, I could. So, the factory walnut stock wasn’t touched. To fit the new double tubes, that stock would have to be routed out. Instead, the factory stock was returned to me as it came, and Lloyd is having a new beech stock made for me by his friend Norm. When that stock arrives, I’ll mount it and return the walnut stock to Norm, who has loaned it to me for photos and to get started with my testing.

Lloyd also produced an upgraded striker spring to give the new rifle more power. Of course, it does reduce the total number of shots; but since the air capacity has been expanded, you don’t notice the reduction over the factory rifle. Lloyd has also provided me with the test data for this performance part.

Benjamin Discovery Disco Double lightweight
My completed Disco Double rifle sits in a beautiful borrowed walnut stock. The Marauder trigger and new triggerguard have now been installed.

Cost
A kit of parts to make your Discovery into a Disco Double costs $165 as of the date of this publication. What you see here will cost $250 in a kit of parts. The aluminum tubes are much more expensive, and I also don’t believe the Marauder trigger has been included in that price.

This first report has been a long one, and we’ve only just begun to see this rifle. The next report will also have a lot more of the background development information, along with some velocity testing.

Oh, I guess I should tell you that this is a .22! And you can forget the serial number because this one stays with me.

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