Posts Tagged ‘Benjamin handpump’
by Tom Gaylord, a.k.a. B.B. Pelletier
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.
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.
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.
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.
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.
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.
by Tom Gaylord, a.k.a. B.B. Pelletier
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.
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.
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.
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.
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.
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.
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!
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.
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.
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!
by Tom Gaylord, a.k.a. B.B. Pelletier
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)
- Slowest shot in acceptable string
+Fastest shot in string
* First gauge photo
** Second gauge photo
*** Third gauge photo
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.
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)
- 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.
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.
So far, I’m delighted with the Lightweight Disco Double. If it turns out to be accurate, it could become my go-to PCP!
by Tom Gaylord, a.k.a. B.B. Pelletier
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.
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:
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
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:
At the end of these 5 shots the on-board gauge read 1,900 psi. That looks like the right pressure to me.
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.
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.
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.
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.
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 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.
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!
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.
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.
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.
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.
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.
by Tom Gaylord, a.k.a. B.B. Pelletier
Today’s report is a guest blog from reader /Dave. He’s going to tell us about his recent experience with a fine precharged pneumatic (PCP) air rifle.
If you’d like to write a guest post for this blog, please email us.
Take it away, /Dave.
Most of you know me as /Dave. I used to be known here as Shooter, until someone was nice enough to recommend the movie of the same name to me. I immediately changed to /Dave because I’m simply not, and never will be, in that league. Please excuse the pictures, they are from my phone.
I have known a lot of people in my life who absolutely must have new when it comes to buying anything. Guns, cars, bicycles…doesn’t matter — anything, really. As if used is somehow not as good, is damaged or is missing the right aura. To them, if it’s not new, it just isn’t right. For those people, I write the following report; as proof that used things are not all bad. This is one of my better experiences with used stuff.
A couple months ago, I bought a used Air Arms S410E bolt-action .22-caliber (FAC version) air rifle from the Yellow Forum classifieds. It showed great promise while I was shooting it and getting to know it in my basement’s 9.50-yard range, but I longed to try it out at a longer range in a relaxed setting, like my backyard. My neighbors are mostly okay with me shooting outside. To make sure they aren’t bothered, I wait to shoot until I have days off during the week when they’re at work.
Dave’s new/old Air Arms S410E air rifle.
I can get a measured 27 yards from the end of my muzzle on my kitchen countertop to the target near the back fence. A friend recently gave me a mechanical rifle rest that he wasn’t using anymore, so I gave that a try. The countertop makes for a nice place to put the rest when you clamp a wide board to it. I usually shoot off a monopod while standing or sitting, so this was much more solid than what I’m used to.
Shooting range from behind the rifle. Sshhh! Don’t tell the wife.
Here’s a look through the new scope I also got from the Yellow Forum classifieds (from a different guy). He bought it, never even took it out of the box and decided to sell it. It has a range-estimating reticle and mil-dots that I have yet to learn to use. So far, I just use the sidewheel focus knob. It seems close enough for government work. There are 36 colors for the reticle illumination! Haven’t tried those out, either.
The view through new, secondhand scope (bought from Yellow but the box was still factory sealed) — UTG Accushot SWAT IE 3-12x44mm, IR, side focus, 30mm tube and set on about 7x. Looks out of focus on the picture, but it’s really clear and in focus when looking through it with my eyes. Sidewheel set on about 26 yds, so it’s not too far off on the factory markings after adjusting the diopter for my eyes.
My backstop is a piece of plywood behind an old crate, and inside — you guessed it — a pile of phone books still in their wrappers!
Backstop at 27 yards.
OK, on to business….
When I received my gun, I immediately pumped it up to its maximum fill of 200 bar (approximately 2900 psi) and started the chronograph testing. Blog reader Kevin Lentz accurately predicted that the sweet spot on the fill would be about 180-190 Bar. Above that, the valve is getting air locked, reducing the velocity of the pellets. I didn’t save the results from my chronograph, a Competition Electronics ProChronoDigital, but I did figure the muzzle energy with each string’s average using this Pyramyd Air’s handy online calculator. With various pellets, it produces anywhere from 26 to 30+ foot-pounds. Lighter pellets generate less, and the heavier ones generate more energy, as is typical with a PCP airgun. This gun doesn’t really start falling off the pressure curve (losing power and velocity) until around 110-120 bar (about 1600 psi), after 60 or more shots.
Pumping it back up to around 190 bar on the gauge takes somewhere around 150 strokes of my Benjamin hand pump. Sounds like a lot, huh? It’s really only 2-1/4 to 2-1/2 pump strokes per shot. I’d call that pretty efficient in terms of energy transfer! While pumping the gun up, I noticed that the gauge on my pump and the gauge on the gun disagreed, so I go by the higher of the two readings just to be safe. That happens to be from the gauge on my pump. During the last couple of months since I received the gun, it hasn’t leaked down any noticeable amount, so I think we’re good there. Chalk one up for used equipment!
What about the accuracy? That’s what airgunning is all about isn’t it? OK, then, on to the shooting results.
At 27 yards on a mostly windless day and shooting off my mechanical rest, I think it does well. As I said, the mechanical rifle rest is a lot more solid than what I’m accustomed to. It doesn’t adjust from side to side except by sliding the back end around, but it has a very fine elevation screw, allowing me to dial in the height very easily. It also has very thick felt v-pads on the front and rear to allow a non-marring, but freely sliding surface to support both the forearm and the butt of the rifle. While shooting my groups, I was also adjusting the scope a bit to get it closer to what I wanted. The clip on this gun holds 10 rounds, so it’s easy to shoot groups of 10. I’ll give both edge-to-edge and center-to-center group measurements for your comprehension. Generally speaking, I think that center-to-center is the standard.
My first group with .22-caliber JSB Exact Jumbo, 5.52mm head, 15.9-grain domed pellets measures about 5/8″ from edge-to-edge, giving me just over 3/8″ center-to-center. You might notice I don’t use calipers. Although I own several, I just use a tape for my groups since that’s usually what I have handy. This same pellet duplicated this group a couple of clips later and is the best pellet of the 4 types shot today at this distance.
My second group was with Air Arms Falcon pellets, 5.52mm head, 13.43-grains, domed pellets. These gave me a 10-shot group of 11/16″ edge-to-edge, or about 7/16″ center-to-center.
The third group was with Crosman Premier .22, 5.50mm head, domed pellets. These are from the box, not the tin. These weren’t terrible at 13/16″ edge-to-edge, or about 9/16″ center-to-center. I think I’ve found something other than my 2240 that will shoot these CP’s with acceptable accuracy!
The fourth group was from the JSB Exact Jumbo Heavy, 5.50mm head, 18.1 grain, domed pellets. At 5/8″ edge-to-edge, or about 3/8″ center-to-center, these matched the 15.89-grain JSBs. Two good choices!
My fifth group was a repeat with the JSB Exact Jumbo .22, 5.52mm head, 15.89-grain, domed pellets from the first group. This was my best group of the day at 9/16″ edge-to-edge, or about 5/16″ center-to-center!
My sixth group was a repeat with the JSB Exact Jumbos from the first and fifth group. I just wanted to verify that I was sighted in at 27 yards. This group is in the upper left of the following picture. The group size is a bit larger due to the fact that I shot away my aim point.
Six 10-shot groups on one fill. One-hundred fifty strokes of the Benjamin handpump to refill to 190 bar from about 110-120 bar. I think that the JSB Exact Jumbo 15.89-grain pellet is the winner of the day. Last group is upper left after scope adjustments.
As you can see, each of the six groups can be completely or almost completely covered by a dime. The largest can be covered with a nickel. All are pretty round, and these are consecutive group; so I’d say this rifle isn’t too pellet picky. Cost for this set-up was less than $600 for the gun and 2 clips plus $100 for the scope. The Accushot scope mounts I already had laying around. All of the pellets that I used today were purchased from Pyramyd Air at one time or another. Can’t beat their 4 for the price of 3 deal!
Am I happy with this gun? Absolutely! But, back to the original question: “Can you get a good, used gun?” Of course! This isn’t my only used gun purchase. Nearly all of my higher end guns are used (I call them higher end but, in fact, they’re more middle range), either acquired from the Yellow Forum classifieds or from Pyramyd Air’s Reman/Refurb/Open Box or Used Gun section. Either I’ve had great luck or this is the norm for me, with the bad apples being the occasional exception.
One of the things that ups my success versus “oops, I shouldn’t have done that” rate is research. In this case, I’d witnessed an S410 FAC sidelever in action. I know that Air Arms has a pretty much stellar reputation; and, from looking at going prices, I knew this one was a pretty good deal — even if it is a bolt-action and the stock isn’t walnut. Not a screaming deal; but at arm’s length, everyone walks away happy deal. I also buy new guns and other things, but I fully intend to keep saving money by careful shopping in the used, remanufactured and refurbished aisles! So can you. You’ll need just a little patience and act quickly when you notice something!