What do YOU want?: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • In an air rifle
  • The marketing
  • Not my idea
  • Last visit
  • So what?
  • The $100 PCP
  • What do YOU want to see in an air rifle?
  • Over to you
  • Summary

In an air rifle

It was February 2006. I’ll never forget standing in the office of Crosman’s CEO, Ken D’Arcy after making my pitch about a single shot precharged pneumatic air rifle that only filled to 2,000 psi.  I was on fire that day, because Ed Schultz had taken my idea and in three days had prototyped two rifles — one in .177 and the other in .22. To his surprise — it worked! He had turned two Crosman 2260 CO2 rifles into prototypes of what the company would eventually call the Benjamin Discovery. [Note: Crosmnan has changed the rifle to a Sheridan 2260.] He was getting 20 shots at almost 1,000 f.p.s. in the .177 and he hadn’t even tweaked the valve yet!

After my presentation and toward the end of the day D’Arcy looked at me and asked me one question. Did I think they could sell a thousand of the rifles in the first year? I had no idea, but I said I thought they could sell two thousand. The idea was sound — it all depended on their marketing.

The marketing

Fully two-thirds of my idea was how to market this new air rifle. It was 2006 and PCPs in general were still looked at as “the dark side.” Crosman had imported some expensive PCPs from England and tried to sell them without success several years before. They had no name in the PCP world.

My idea was to put everything the shooter needed into one box and to price it at $250 out the door. It would have the rifle, a hand pump, a small tin of good pellets (this was Crosman, so I was thinking Premiers) and a bunch of good literature. Not only would there be a solid owner’s manual that I would help write; there would also be a “Welcome to the World of Precharged Airguns” pamphlet that explained how the rifle worked. That would dovetail with online tutorials on how to fill the rifle with either a pump or a scuba tank, an explanation of how the scuba tank would last a long time because the gun was only filled to 2,000 psi, and an explanation of how just 2,000 psi was enough to propel a .177 pellet to 1,000 f.p.s.

Not my idea

Folks — the Benjamin Discovery was not my idea. I would love to be able to claim it, but the idea really came from Larry Durham and Tim McMurray. They built a field target rifle called the USFT that got a large number of shots from a very low-pressure fill.

My USFT from Tim McMurray filled to 1,600 psi and got 55 shots of 10.6-grain Beeman Kodiaks at just under 900 f.p.s.

The test target Tim sent with my rifle. It’s 25 Beeman Kodiak Match pellets in 0.663-inches at 51 yards.

USFT best target
My first time out with the USFT my best 5-shot group at 50 yards was 0.335-inches, c-t-c.

What I’m telling you is I am not the inventor of the Benjamin Discovery. I just saw a great idea and took it to some folks who could do something with it.

As I was about to leave Crosman for the airport that same day, Ed Schultz showed me a rack of walnut stocks that were in-process. Some were finished, some were awaiting finish and some were raw lumber waiting to be turned into stocks. He told me there were 4,000 stocks that had been for a special 2260 project that was cancelled. He said he was of a mind to put them on the first Discoverys. Imagine getting a budget PCP package that included a rifle with a walnut stock!

Well, in 2007 Crosman did exactly that — they put a walnut stock on the first Discoverys. I have one that I bought (no — they didn’t give me a rifle, but I was paid for this project) from my buddy, Mac, at one of the last Virginia airgun shows. Toward the end of that first year I noticed that they had switched to beech stocks, so I reckoned what I had told Ken D’Arcy the year before held up.

Last visit

I went back to Crosman one last time to discuss the project and was shown their first rifling machine for the Discovery. Ed also told me they were testing the first rifles for holding by filling them and watching them for 24 hours. They knew they had to do it right from the start or risk sniping from the internet peanut gallery. I told Ken D’Arcy that in two years Crosman, a company known for kid’s guns and CO2 guns, would be a household name in the PCP world.

So what?

Okay, that was an idea that I got to see all the way through to fruition. There were changes along the way, as there always must be, but Crosman remained true to the core idea. And it worked better than I hoped. The next year they brought out the Marauder that they had been planning all along. But they took my advice and launched the Discovery first to establish a reputation in the world of PCPs. Today there are airgunners who are unaware that Crosman came into the game as late as 2007.

The $100 PCP

In 2014 I did a 6-part series where I tested an airgun Dennis Quackenbush made up for me. He took a Crosman 2100B and turned it into a PCP. I asked him to hold the cost as low as he could and when he was done we both felt it was possible to build a precharged pneumatic that could retail for one-hundred dollars.

At the 2016 SHOT Show, Crosman surprised me with their Maximus — a new PCP that retailed for $200. Guess what — it still does today — over four years later!

The Maximus looks similar to the Benjamin Discovery and will retail for under $200. A complete package with a pump and pellets will retail for about $430.

The Maximus is probably the big reason the Discovery is no longer made. They don’t need two budget PCPs and the Maximus was cheaper. It also had their new barrel that is more accurate by virtue of being reamed before rifling. So 2007 to 2016 is a nine year period in which Crosman went from being the maker of airguns for kids to one of the top makers of PCPs in the world! — nine years!

What do YOU want to see in an air rifle?

That’s a long intro for the title subject, which is — if you had your way, what sort of air rifle would you like to see? I’ll get you started. I would like to see a Sig ASP20 with some changes.

Keep the barrel, but shorten it by 4 inches. Keep the gas spring, but let out some air so the rifle with the shorter barrel cocks with 20 pounds of force. If necessary, put a longer muzzle brake on the barrel to increase the length for leverage but not the weight. Lighten the synthetic stock by a significant amount and thin its profile at the grip and forearm where the hands fall. Keep the trigger and safety exactly as they are.

What you are giving me is a 12-13 foot-pound breakbarrel air rifle that’s 1.5 pounds lighter and a lot easier to cock and to hold. And, now that it’s all that, folks will want open sights. 

When Ed Schultz was still at Sig I gave him an idea for an open front sight that would be revolutionary in the world of airguns. It’s been in use in the firearms world for the past 80 years, but I haven’t seen it on an airgun yet. With that dandy Picatinney rail that’s on the rifle right now Sig could offer an adjustable rear sight that would attach easily. I recommend offering a peep , but it could also be a conventional notch if it could be extended forward far enough for the eye to see.

There you are, Sig. That’s a new SKU for you that won’t cost you very much engineering time to create. I bet an engineer could knock out a prototype in a week, if his time was dedicated.

Over to you

Now it’s your turn. Tell us what air rifle you would like to see. Here is a tip. Companies are not likely to get out a clean sheet of paper for anything. When they do that, they are looking at heavy 6-figure investments. Give them something that’s easy for them to do — but for some reason they haven’t done it yet. What if we sliced the loaf of bread before selling it — that kind if thing.


Want to affect the world of airguns? Then stop tipping over the porta-potties and help us empty the garbage cans!

Gamo Swarm Fusion 10X Gen II air rifle: Part 4

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2
Part 3

This report covers:

  • The test
  • Sight in
  • Falcon group
  • Discussion
  • RWS R10 Match Pistol pellets
  • Discussion 2
  • JSB Exact RS dome
  • Discussion 3
  • Second group of JSB Exact RS
  • Third group of JSB Exact RS
  • Summary

Today I mount the 3-9X40 Gamo scope and shoot the Fusion 10X from 25 yards. It will be an interesting test.

Mounting the scope

The scope that’s bundled with the rifle comes with a one-piece mount already attached. All you have to do is loosen the three Torx screw on the scope mount base with the wrench provided and clamp the mount to the 11mm dovetail base on the rifle. The mount has a scope stop pin that fits into the rear hole in the base and locks the mount from moving under recoil. I had the scope on and ready to go in 10 minutes.

The test

I shot off a rest at 25 yards. I used pellets that showed potential in Part 3’s test with open sights, except I had run out of H&N Match Green pellets, so I substituted something else.

I shot with a modified artillery hold, since I learned in Part 3 that the rifle likes that best. I actually modified my hold as the test progressed and I will tell you about it as we go. Let’s get started!

Sight in

I sighted in from 12 feet with Air Arms Falcon pellets. The first shot hit the paper at my aim point, which means it will climb higher as I move back, so I backed up to 10 meters and fired a second shot. Shot two was higher and also to the left. It was close enough to the aim point that I backed up to 25 yards to refine the sight picture. It took a couple more shots to get the rifle shooting where I wanted and then I fired the first group. While most of my groups today will be 10 shots, this first one was only 5 because I was also testing whether loading single pellets or loading all 10 into the magazine worked best.

I’m not going to show the first 5-shot group because it overlapped a couple sighters and isn’t easy to see. But now I loaded the magazine with 10 of the same Falcon pellets and shot a group.

Falcon group

The ten-shot group of Falcons was revealing! It was looking to be a good group until the final four  shots. The group grew from 0.475-inches between centers to 1.554-inches. 

Falcon group
Ten Falcon pellets went into 1.554-inches at 25 yards. The first 6 of them are in 0.475-inches.


Before we move on I need to tell you what I think is happening. First, I believe the hold is the most essential part of accuracy with the Fusion 10X. Unfortunately it has a thumbhole stock that cannot be held as loosely as I would like, but a loose artillery hold is a key to the rifle’s accuracy.

Next, I don’t think there is a large difference between loading pellets one at a time and loading the entire 10-shot magazine. And the way the Fusion 10X works, using the magazine is certainly easier. I finished the test shooting from the magazine.

The scope is reasonably clear at 25 yards. I adjusted the eyepiece until the crosshairs were sharp through my everyday glasses, and I could see them on top of the 25-yard bullseyes.

For a bundled scope this one isn’t bad. And the fact that it comes with the mount already installed on the scope is a plus for those who don’t like mounting their own optics.

Finally, I don’t believe that Falcon pellets are necessarily the best in this rifle. I will try some other types. I did not adjust the scope after this group.

RWS R10 Match Pistol pellets

Next to be tried were ten RWS R10 Match Pistol pellets. These landed low and left of the bull. The group measures 1.397-inches between centers and once more there is a tighter cluster of five in the center of the group. There were not shot in succession, but for each of them I was extra-careful to hold the rifle lightly. Now I am learning something!

R10 group
Ten RWS R10 Match Pistol pellets went into 1.397-inches at 25 yards. The aim point was the bullseye at the upper right.

Discussion 2

Okay, I think I have it figured out. The Gamo Fusion 10X is very sensitive to how it is held. It is also pretty accurate, but only when the hold is right. The pellet probably does not make as much difference as it will appear in this test, but I did move on to the JSB Exact RS dome.

I also believe that feeding pellets from the magazine does not detract from the accuracy. Maybe I’m talking ahead of my test results now, so let’s move on and I will show you.

JSB Exact RS dome

I had left the scope adjusted where it was after my first 5-shot group and both the second and third 10-shot groups and now I could see the Fusion 10X was shooting too low and left. So I adjusted it 5 clicks up and two to the right. Ooops! Should have waited to shoot the JSB Exact RS domed pellets first. Because the 10 JSB pellets landed to the right of the bull. The elevation seemed correct but the windage was off to the right.

Ten JSB Exact RS pellets went into 1.046-inches — BUT only the first three shots are high and horizontal. I then slid my off hand out to the end of the cocking slot and shot the next 7 shots into a group that measures 0.648-inches between centers. For 25 yards that’s not that bad! In fact this group was so impressive to me that I drew a circle around the last 7 shots, to separate them from the first three shots.

RS group 1
The first group of 10 JSB Exact RS pellets went into 1.046-inches between centers. The final 7 shots that I really concentrated on are in 0.648-inches, which is inside the circle.

Discussion 3

You must be wondering why I couldn’t REALLY concentrate on the first three shots, if I knew what was happening. Let me explain. When you shoot with the artillery hold there is a final step that is sometimes critical, and other times not. Before you squeeze off the shot you close your eyes and relax, then open your eyes and see where the crosshairs are. If they have moved from where you want to hit, you make small adjustments of your hands and elbows and then do it again. You keep doing it until the crosshairs are still on target after you open your eyes. Then you take the shot.  This takes time and a LOT of concentration, but as you shoot a rifle more and more, it starts to become second nature.

It takes a lot of concentration for every shot, but I can do it when I have to. And with this rifle it seems necessary.

Second group of JSB Exact RS

JSB Exact RS pellets seemed like a good pellet to test, so I adjusted the scope three clicks to the right and two clicks up and shot a second 10-shot group. I did my very best this time and 10 JSB Exact RS pellets went into 0.959-inches at 25 yards. That’s not enough different from the last group to say much of anything.

RS group 2
The Fusion 10X put 10 JSB Exact RS pellets into 0.959-inches at 25 yards. This group is a little more to the left and a little higher, but not much!

That was the best I could do. But my conscience still argued that I should have done better. I was tired but still functional, so I shot one final group. This time it was just five shots. I figured I could hold it together that long. I adjusted the scope up two clicks and right three clicks.

Third group of JSB Exact RS

This time I pulled out all the stops on each shot. And it worked! I was able to put five pellets into a group that measures 0.495-inches at 25 yards. To tell the truth I wanted to shoot a second five shots, but I was concerned I wouldn’t have anything to show you. Other airgunners shoot five shot groups as a matter of course, so there you are!

RS group 3
The Fusion 10X put five RS pellets into 0.495-inches at 25 yards.


The Gamo Swarm Fusion 10X GenII repeating pellet rifle is a remarkable airgun. It is smooth, accurate and has a reasonably nice trigger. Its GenII 10-shot magazine lies flat for a low profile, yet the rifle feeds very reliably. It’s easy to load and even easy to fire single-shot without removing the magazine.

This gas spring-powered breakbarrel rifle is easy to cock. It’s not a mega-magnum by any stretch, but it’s a good honest .177 that develops almost 15 foot-pounds. Yet I can cock it easily with one hand.

The rifle is lightweight, yet does not vibrate or recoil very much when it fires. And all of this comes to you with a scope for under $300. Gamo has done very well with this one.

Determining muzzle velocity

by Tom Gaylord
Writing as B.B. Pelletier

This is another guest blog from reader Dennis Baker. He sent this to me based on the comments several of you made to his last guest blog.

If you’d like to write a guest post for this blog, please email me. Now, over to you, Dennis.

Determining muzzle velocity

By Dennis

This report covers:

  • Introduction
  • Background
  • Trajectory
  • ChairGun Pro trajectory calculation
  • Comparison of observed and calculated trajectories
  • Error assessment
  • Conclusion


How does one determine muzzle velocity? Well, mostly with a chronograph. But if you don’t have a chrony, and don’t want to spend the hundred or so bucks to buy one, use it once, and have it sit around the house taking up space and using up air for the rest of its life, there is another, though less convenient, option. Read on …


In my recent review of the BSA GRT Lightning XL SE (.22 caliber), I reported in Part 1 that the ten-for-ten chrony test of the gun on initial purchase had indicated an average muzzle velocity of 767 fps with 11.9-grain pellets. In a comment, I discussed several issues and showed results of several groups shot at 15 yards. I was encouraged to shoot at greater distances and show results in Part 2. Blog reader Yogi noted that the reported velocity was about 100 fps higher than he had seen in other reviews. In response to Yogi’s comment I mentioned how the free application, Hawke ChairGun Pro, could be used to infer the muzzle velocity. Using this application it was possible to infer that the muzzle velocity of my Lightning was indeed about 100 fps below the ten-for-ten measurement: about 665 fps. Note, that my review used a heavier pellet than the one used in the ten-for-ten test. I found the 14.66-grain, H&N Field Target Trophy to be a good pellet for my gun, so this is what I used in the reviews.

Another blog reader, Chris USA, suggested that it might be of value to post a blog article showing how to use trajectory to infer muzzle velocity. So you can blame Chis for this post!
If you wish to read the original review articles here are the links.
Revisiting the BSA GRT Lightning XL SE: Part 1
Revisiting the BSA GRT Lightning XL SE: Part 2


The first step is to determine the actual trajectory of the pellet. This is done by shooting groups at intervals throughout the ranges of interest. In my case, as I am interested in backyard shooting, the ranges of interest were from about 10 yards to about 40 yards. After zeroing at twenty yards, shooting four shot groups (for the most part) at five yard intervals yielded the following trajectory.

trajectory 10 to 40 yards
Trajectory — 10 top 40 yards.

Eyeballing a curve through these groups shows the pellet trajectory through the ranges of interest. The trajectory shows that the POI was about one inch low at ten yards and 40 yards, and about 1/8 inch high at 25 yards.

trajectory 10 to 40 yards with curve
Trajectory, 10 to 40 yards with curve.

ChairGun Pro trajectory calculation

Now, if one can fit a similar trajectory curve using a mathematical calculation (or a computer application), one can determine the muzzle velocity of the pellets. Turns out, there is an application that permits this. It is ChairGun Pro from Hawke. Here is the link to the downloaded page.

The application allows you to play with input parameters in order to attempt to match the trajectory curve. You get a visual response in real time. The critical input parameters are as follows:

• Pellet weight and ballistic coefficient – The application has a database, or you may be able to get these from the manufacturer web page as I did for the H&N FTTs.
• Muzzle velocity – You play with this parameter last as you attempt to match the trajectory. My final result indicated a muzzle velocity of about 665 fps. This compares well with the manufacturers stated velocity of 670 fps. Go figure?
• Zero range – The range at which your rig is zeroed on target.
• Sight height – The distance between the center line of the bore and the center line of the scope. I found this parameter to be very critical.
• Start range/End range – The nearest and farthest ranges to the targets. In this case 10 and 40 yards.

The following image shows the parameters (circled on the image) and the resulting trajectory curve.

ChairGun Pro graph
Screenshot of ChairGun Pro showing critical parameters

Comparison of observed and calculated trajectories

The following table shows a comparison of the POA/POI differences measured in inches from the actual target set (using the curve) and those calculated by ChairGun Pro.

comparison graph
Comparison of observed versus calculated differences in POA and POI at ranges from 10 to 40 yards.

For a visual comparison, here is an overlay of the ChairGun Pro trajectory on the targets image.

overlay of trajectories
Overlay of ChairGun Pro trajectory on targets image.

In this overlay, the scale of the ChairGun Pro image was adjusted to match the scale of the targets image, i.e. the length equal to the 10 to 40 yard scale and the 1 inch vertical scale equal to the 1 inch targets. As can be seen, the images are not an exact match. The observed trajectory (targets image) does not fall off quite as quickly as the ChairGun Pro trajectory (red) at 10 yards and at 40 yards. This will be discussed in the error assessment section that follows.

Error assessment

There are quite a number of possible sources of error in this demonstration. Here are a few.

• All of the distances were paced out, not measured. So each may be off by a foot or so either way. This includes the zero distance.

• The curve fit to the trajectory shot in the field was not calculated but only eyeballed in using a simple graphics application – so not the most precise fit in the world.

• Some error may be introduced in the visual comparison when trying to match the scales of the two trajectory curves.

• The scope height was difficult to measure with precision, and this parameter impacts the velocity used to best fit the target image.

There are uncertainties introduced by each of these possible sources of error. For instance, one can show a flatter trajectory with ChairGun Pro by decreasing the scope height 0.2 inches and increasing the muzzle velocity to 685 fps. This better matches the trajectory that was realized in the field, but it doesn’t match the measured scope height.

All-in-all, I feel pretty confident in saying that the muzzle velocity of this rifle with this pellet is in the neighborhood of 665 to 685 fps. This is pretty close to the 670 fps velocity reported by the manufacturer. That’s my story, and I’m sticking to it!


Clearly it is much easier to determine muzzle velocity by measurement with a chronograph. But if you don’t have one, or if you want the challenge of working it out yourself, or if you just have a lot of spare time on your hands, it is possible to get a good approximation using the approach demonstrated in this article. If you feel I’ve wasted your time here, don’t blame me! As I said in the Background section, blame Chris USA!

Diana model AR-8: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

Diana AR-8
Diana AR-8 N-TEC air rifle.

  • The rifle
  • Big!
  • Inexpensive?
  • Sights
  • Scope base
  • Trigger
  • Firing behavior
  • Summary

The full title of the rifle we are looking at today is the Diana AR-8 Professional Success. That’s right. Apparently the Germans have hired Koreans to name to their airguns. Remember Shin Sung — Good Luck for Dignified Masterworks?

The rifle

The rifle I’m testing is a .22, but it also comes in .177. The serial number I’m testing is 20067725. The name AR8 is derived from the Blaser R8 Professional bolt action rifle, though that firearm bears little physical resemblance to this air rifle. Perhaps they mean similar in performance within the airgun world.

The AR-8 has a gas piston unit — the Diana N-TEC piston. That is a unitized piston assembly with an internal gas spring. I tested one before in the 340 N-TEC, and I know how nice it can be. Let’s hope the AR-8 tests just as well.


The AR-8 is a large air rifle. It’s 48 inches long and weighs 7.2 lbs. You know you are holding something when you heft this air rifle. The stock is black synthetic, shaped with the rounded forend Diana is putting on many of their rifles these days. There’s the hint of a schnable at the tip. Fine stipple-like texturing on the forend and pistol grip is too smooth to give any grip, and the stock feels slippery in my hands.

I find the cross-section of the forend too wide for comfort. The pistol grip is very vertical and thin, so it feels good to me with my medium-sized hands. The butt has a thumbhole cutout that’s ambidextrous, and I like it. I’m not a fan of thumbhole stocks, but for a airgun this inexpensive, I think it compliments the rifle.


Why does B.B. think $350 is inexpensive? Because this is a Diana! You get their accuracy, an adjustable trigger (no, I don’t think it’s T06, or if it is, everyone is sworn to keep it a secret), and reputation for build quality. Plus it has a gas piston/spring. Just because it’s a Diana you know I.m going to test for barrel droop! But, yes, at $350, this could be a terrific bargain.


The sights are unlike any I’ve seen! I wish I had designed them.

The front sight adjusts for elevation. A thumbwheel raises and lowers the sight element, and the pellet moves in the opposite direction.

Diana AR-8 front sight
The front sight adjusts for elevation, via a thumbwheel!

The rear sight is unique. A broad white stripe points to a shallow squared notch where the front sight should be centered. But that white stripe causes me to want to center the green front fiberoptic dot above it, in a “snowman” configuration. My Taurus 1911 pistol has something similar and once I got used to it, I liked it a lot! The jury is out on this one, but at least the engineers at Diana are trying.

The rear sight has a locking screw on either side of the sliding notch. Loosen them both and slide the sight in the direction you want the pellet to go. Then lock them down. I haven’t seen this arrangement on a pellet rifle in a long time!

Diana AR-8 rear sight
The rear sight has a small Allen locking screw on either side. Loosen both, then slide the sight in the direction you want the pellet to go.

Scope base

The AR-8 has a traditional Diana scope base atop the rear of the spring tube. All your recent Diana scope mounts will fit it. Will you need a drooper base? I will test for that.


OMG!!! Trigger fanatics are going to love this adjustable trigger! It is extremely crisp and very light. Details in Part 2. I am betting it is breaking at under 2 lbs. out of the box.

There are three adjustments the user can make. The first stage travel is adjustable and the factory sets it at the minimum. I don’t care for it, but those who like single-stage trigger certainly will! And I can adjust it to suit me.

Diana AR-8 trigger
The trigger adjustment screws are so deep inside that I couldn’t capture them. There are three — one behind the trigger and two in front. Note the straight trigger blade.

Both the stage one and stage two pull weights are also adjustable. I have seen some Rekords that couldn’t be adjusted this nice. And the blade is very straight, which is my personal preference.

Firing behavior

I cheated, like I always do, and fired a couple shots. The stock slapped my face like a woman, when I got too fresh on the first date! I really hope that goes away (the stock slap — not the women).

The rifle is detonating right now, and the firing behavior should change when that ends. I really hope it does, because this will be painful to shoot for accuracy, if not.


The Diana AR8 has many differences. It’s not just another breakbarrel with a new name. This is one to examine carefully. That’s what I plan to do.

Octane combo from Umarex — trigger job: Part 5

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

Part 1
Part 2
Part 3
Part 4

Octane combo
Umarex Octane gas spring combo.

Today’s report is a guest blog from blog reader DMoneyTT. He promised to show us how to fine-tune the Octane trigger, and he’s provided some good photos to go along with his article.

If you’d like to write a guest post for this blog, please email me.

Over to you, DMoneyTT.

Umarex Octane trigger job

by DMoneyTT

As the cost and availability of firearm ammunition continues to keep many shooters from getting adequate trigger time, scores of shooters are turning to airguns to keep their skills honed. Often, new airgunners will be tempted to put down their hard-earned dollars on a rifle offering the highest advertised velocity. Airgun marketing tends to focus on this aspect of performance over all else; but experienced shooters know that accuracy is paramount, and it takes more than just a good barrel and powerplant to deliver tight groups. Proper fit and trigger control are critical considerations when attempting to extract the maximum potential from any rifle.

It’s no secret that the Chinese-manufactured airgun market has seen unparalleled growth and their products are steadily closing the gap between these affordable rifles and their more precise, yet costly, brethren manufactured in Germany, Russia, the United Kingdom and the United States (to name but a few). Many times the differences in quality of manufacturing may be ironed out by the end user. It’s not beyond the skills or tools of the average shooter to dramatically improve the performance of a budget Chinese airgun.

For the shooter who desires all the power of a magnum springer and wants the accuracy to make good use of the velocity but doesn’t want to spend a lot, there are a few good choices. In my humble opinion, the best of these is the Umarex Octane combo. I picked one up several months ago, and it’s been a real joy to plink with and should be excellent for hunting small game, as well. The only downside to this excellent rifle is the trigger-pull. Out of the box, the pull on my rifle registered almost 10 lbs. Others have reported slightly less, so I may have started with an abnormally high pull weight to begin with. There was very little creep (which is a result of minimal sear engagement), and the break was quite crisp. So, a trigger job was necessary, and lessening the pull weight was the only task required.

I would like to say that this does take a steady hand, and careful attention should be paid to the work done on these tiny parts. Any work you decide to do on your rifle should be done with care to maintain the original parts geometry, and it’s always a good idea to carefully test the rifle after any work has been performed. I suggest reading this article before beginning any work to decide if this is within your skill set.

Note from B.B.: Do not work on your gun’s trigger if you do not already have experience working on airguns or are not 100% confident that you can properly disassemble and reassemble the gun and trigger. If you decide to do any part of this trigger tune, you will void the gun’s warranty.

The necessary tools are few.

You will need:
• An Allen wrench that fits the forearm screws.
• A large Phillips screwdriver
• Some paste-type lubricant (synthetic open-gear lube worked well for me)
• A fine wet stone (300-600 grit is preferable)

• A Dremel (or any other rotary tool) with a grey rubber polishing wheel may be used on contact points other than the primary sear and secondary sear interaction point because it’s too likely to round edges.
• A vise to hold the rifle while performing the work.
• Small needlenose pliers or hemostats.

So, let’s begin! Start by ensuring that the rifle is not cocked or loaded. The next task is to remove the stock from the rifle so the trigger group can be accessed. Use an Allen wrench to remove the two forearm screws that attach the action to the stock.

Octane combo forearm screws

Next, a large Phillips screwdriver is used to remove the screw found behind the triggerguard.

Octane combo Phillips screw
The action can now be removed from the stock. It’s helpful to hold the rifle directly upside down, as the trigger pins fit very loosely and will fall out if the action is tilted to either side once the stock is removed. It’s wise to do all the work over a flat and clean surface that will easily allow dropped parts to be seen and recovered. I chose to mount my action in a vise to allow easy removal of the stock and to gain access to the components of the trigger group. It’s certainly easier to work on the rifle if both hands are free.

Here is the correct placement of the pins in the trigger housing.

Octane combo trigger pins

Each pin will now need to be removed, and the associated component will need to come out with it. I find that hemostats are very helpful for those with large hands like mine. To help organize the parts, it’s advised to lay them on a white sheet of paper according to their position as they’re removed.

To illustrate the internal layout of the parts, I assembled a jig to hold the pins in the same position they are within the trigger housing. Notice that the shorter leg of the V-shaped sear spring rests against the secondary sear. This is important to reproduce when assembling the trigger group.

Octane combo trigger parts
These parts are shown upside down. In the rifle, the trigger blade would be on the bottom of these parts.

Now that the components have been removed from the trigger housing, warm soapy water should be used to degrease all the parts. All contact points between the parts should also be deburred and polished. These areas are circled below in red. I first used a fine (500 grit) whetstone to debur and smooth any rough surfaces. I then polished these parts with a very fine (1000 grit) whetstone. Remove as little metal as possible to get the desired mirror finish and be careful not to round any of the sharp edges. The goal is to make the parts smooth and shiny so they’ll slide against each other with minimal friction but not alter the shape of the parts.

Octane combo trigger parts cocked

Like the previous photo, these parts are also shown upside down.

Octane combo trigger parts fired
Perhaps the most important part to refinish is the trigger adjustment screw. It comes from the factory with a very sharp point that digs into the tertiary sear where it touches. This galls the metal, and there’s significant drag produced when attempting to pull the trigger in its stock configuration. Simply removing this grub screw with a small Allen wrench and rounding and polishing the end that contacts the tertiary sear will reduce the pull weight by 2 or more pounds, depending on the severity of the galling.

I chucked this screw into my drill and spun it against my whetstone until it had a nice, smooth ball end instead of a sharp point. It should look like the image below when you’re done.

If you are not confident enough to tackle this full trigger job, the trigger adjustment screw can be removed from the rifle without any other parts being removed. That allows you to round and polish the end and install it in the trigger to realize a vastly improved trigger-pull with little work involved.


Octane combo trigger adjustment screw

The adjustment of this screw has very little effect on the pull weight or quality because it allows adjustment of the first stage only. This first stage is not a true first stage because the sears do not move as the trigger travels through this stage. The trigger return spring is just being compressed, much like a Gamo or Crosman trigger. Feel free to adjust this screw to whatever position you prefer. There’s no set rule except to not adjust the screw so far in that it eliminates the first stage. That will result in an unsafe rifle that may cause a bear-trap incident (where the piston releases without the trigger being pulled, allowing the barrel to snap shut unexpectedly).

Assembly of the trigger is fairly straightforward and is the reverse of disassembly. The use of a thick paste-type lubricant on the bearing surfaces of the parts will help decrease pull weight as well. I use Mobile One synthetic open gear lube, but most any paste-type lubricant should work. My Octane trigger group was bone-dry from the factory, which certainly contributed to the very stiff pull weight. Use the pictures to help install the parts and pins in their appropriate locations. The hemostats will come in handy again at this point. I installed washers to remove slop from my components but would not recommend it. The difference is hardly noticeable, and it makes assembly much more difficult.

The sum of these modifications should get the trigger-pull down to around 4 lbs. and make it much more smooth and consistent. After averaging the pull weight from 5 measurements, my trigger has settled down at a 3 lb., 2 oz. pull. It’s possible to go slightly lighter with some modifications of the secondary sear geometry; but because of the required precision and the possibility of dangerous results, I suggest stopping at this point. A 3.5-lb. trigger is quite good for a magnum springer and is ideal for accurate plinking and hunting. I know that my groups have improved dramatically, and I’m enjoying the fruits of my own labor when I feel a crisp trigger-break and see targets fall. I hope this helps you get the best from yourself and your rifle.

Please post any questions, comments or tips you have. I’m curious to see what you think.

Octane combo from Umarex: Part 4

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

Part 1
Part 2
Part 3

Octane combo
Umarex Octane gas spring rifle combo.

Today’s report is both interesting and a little different. I shot the .22-caliber Octane combo from Umarex at 25 yards and used the Umarex 3-9X40 scope that came in the package. I’ll talk about the scope and mounts first.

The scope is a variable with parallax adjustment from 10 yards to infinity. It features a duplex reticle and comes with 2-piece Weaver rings that have 4 screws per cap. The top of the rifle has a Picatinny adapter clamped on the 11mm dovetails that are cut directly into the spring tube, so the scope rings mounted quickly.

I found the scope to be clear and sharp, and the parallax adjustment to be close to the actual distance once the eyepiece was adjusted correctly. This is one of the nicest scopes I have seen bundled with a combo airgun. I don’t think you need to buy anything other than pellets — lots of pellets.

I sighted-in the gun at 12 feet with one shot, then backed up to 25 yards to refine the sight picture. Veteran readers know I’m purposely trying not to hit the center of the bull, as that erases the aim point.

I was finished sighting-in after 4 more shots and ready to start shooting for the record. The first pellet I selected was the .22 caliber 14.3-grain Crosman Premier that had done so well in the 10-meter test with open sights.

After the first 5 shots, I thought I had a slam-dunk accurate rifle, but I guess I got a little sloppy. Shot 6 went into the same hole, but shots 7 through 10 moved over to the left of the main group. Six consecutive shots went into 0.449 inches; but after 10 shots, the group measured 1.067 inches.

Octane combo Premier group 1
The first 6 Crosman Premiers went into a tight 0.449 inches, but the remaining 4 shots opened the group to 1.067 inches at 25 yards.

After this group was finished I discovered the scope base screws were both loose. That made the scope loose, as well. I tightened them and checked them frequently throughout the remainder of the test.

The second group of Premiers opened to 1.382 inches. This one is very horizontal, but within it is a tight group of 4 shots that came early in the string. That group measures 0.188 inches between centers.

Octane combo Premier group 2
These 10 Premiers are not very impressive for 25 yards, at 1.382 inches between centers; but at the 9 o’clock position on the bull, 4 pellets went into a tight 0.188 inches!

Following this group, I noticed that both forearm screws had come loose. So they were tightened — a lot! And for the rest of the test, I monitored their tightness closely.

What’s happening?
The Octane recoils a lot, and you have to watch all the screws. Once they’re tight, they probably won’t back out for a long time; but the first time you use the gun, they probably need to be tightened just a bit more than normal. At least, watch for them to loosen.

This is nothing new. We have always been told to watch the screws on spring guns that recoil heavily. I just forgot it this time until it became obvious downrange.

JSB Exact Jumbo
Next I tried JSB Exact Jumbo pellets. They did very well for the first 6, then the last 4 wandered over to the right. And when I say “wandered,” I mean they really went places! The group measures 2.822 inches between centers, with 6 of those shots in 0.763 inches.

Octane combo JSB Exact Jumbo group
Interesting group! Six shots in a tight 0.763 inches, then the last 4 stretched it out to 2.822 inches. Go figure!

After this group, I played around with holding my off hand at different places under the forearm, and then some non-standard holds that included resting the rifle directly on the bag 2 different ways. By the time I was finished, I’d fired over 60 shots from a rifle that takes 39 lbs. of force to cock. I never reported that effort in Part 2, like I normally would, so now you know that the Octane is hard to cock — like all powerful gas spring airguns.

I suspected that I was tiring at this point. The term used in competition is I was “blowing up”! The Octane wanted to put them in the same place, but something prevented it. I shot one final group of Premiers — just to see if I could see what it was doing. But that group wasn’t worth reporting. I had clearly pushed past the point of fatigue, so the session was over.

Here’s what’s at stake. Priced at just $200 with a very good scope, the Octane is poised to take its place beside legendary air rifles like the RWS Diana 34 Striker Pro combo. It’s actually $100 less than the 34, yet offers the same power. If it also gives the same accuracy, the Octane suddenly becomes an important air rifle; and if the horribly heavy trigger has a workable solution that the average owner can follow, then folks, we have a winner. So, I want to give this air rifle every chance to compete. It seems to want to do well, so I need to find out what needs to be done.

Octane combo from Umarex: Part 3

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

Part 1
Part 2

Octane combo
Umarex Octane gas-spring rifle combo.

Today is the start of accuracy testing for the Octane combo air rifle, and I’m going to make some changes. For starters, I’m going to give you the summary now. The Octane is a smooth-shooting, accurate air rifle. It’s everything the manufacturer wants it to be, and a couple of things they probably didn’t think about, on top of that. The rest of this report will justify and explain my summary.

Another thing, the Octane is different from any gas spring I’ve ever tested. Gas springs always fire fast, as in instantaneously. When the sear releases, the shot is over, and you usually know it from the sharp crack of sound and the painful slap to your cheek. The Octane fires slowly in comparison. There’s a lot of forward recoil and almost no vibration, and the discharge is very quiet, as I noted in part 2. I attribute this behavior to the Reaxis gas-spring design that’s reversed from the norm, and to the SilencAir silencer on the muzzle. Both apparently work as advertised.

The test
I decided to just shoot 5 shots per pellet today, and to shoot the rifle with open sights at 10 meters. I wanted to get a good sense of how accurate it is before putting the walls of my house at risk. And what I discovered was that this rifle is fun to shoot! I normally don’t have much fun shooting a 20 foot-pound spring rifle, but the Octane is so civilized that it gave me a lot of confidence. By the time I’d fired the first 2 shots at the target, putting them into the same hole, by the way, I knew this day was going to be fun.

I held the rifle with an artillery hold, but the thumbhole stock makes you grip the gun harder than you normally might. So, I would have to call it a modified artillery hold. But the rifle cooperated, and there was noting to worry about. The muzzle heaviness holds the front sight steady on target once you’re dialed in.

The sights are fiberoptic, which destroy all attempts at precision, but by lighting the target brightly and sitting in a darker room to shoot, I could defeat the fiberoptic tubes and get a very sharp sight picture. When they don’t glow, the Octane’s sights offer a nearly ideal sight picture, and that was what made me decide to not mount the scope, yet. I wanted to have the fun of shooting with open sights since the rifle was cooperating.

The trigger is still quite heavy and very creepy, so I envy those who own their rifles and can modify them. If I could drop the release weight to under 4 lbs. and if there was a way to eliminate all the second-stage creep, this trigger would help accuracy greatly.

Beeman Kodiaks
The first target was shot with 5 Beeman Kodiak pellets. This was when I first noticed how slow the Octane’s gas piston is. It feels like an airgun equivalent of a 45-70 single-shot. You feel the recoil and the rifle bounces around, but you know the pellet got out of the muzzle before all that started and that accuracy wasn’t affected in the slightest.

As I said, the first 2 pellets cut the same hole, though each made a distinctive mark. Then I stopped watching through the spotting scope and just shot the next 3 pellets. In the end, the group is larger than I would have liked for 10 meters, at 0.581 inches, but this is with open sights. Still, it is just 5 shots instead of 10.

Octane combo 10-metr Kodiak target
Five Beeman Kodiaks at 10 meters with open sights measure 0.581 inches between centers. It’s a good start!

RWS Hobby
Next, I tried the RWS Hobby pellet. It felt good while loading because it fit the breech tight but not overly so. And, though the point of impact shifted up a bit, the Hobby was quite accurate — putting 5 pellets into 0.368 inches! I thought that was remarkable. I couldn’t wait to test some more pellets!

Octane combo 10-meter RWS Hobby target
Five RWS Hobbys at 10 meters with open sights measure 0.368 inches between centers. Now, the rifle was giving me confidence.

RWS Superdome
Next, I tried the RWS Superdome. Here’s where you’re going to see something significant. RWS makes both Hobbys and Superdomes in Germany, and presumably they use the same lead alloy for both. And domed pellets are generally regarded to be the most accurate. Yet look at how the Superdomes did! They grouped horizontally, to exactly 1 inch, while the Hobbys stayed together.

You might try to blame me for getting tired at this point in the test, but there’s group coming that will show that I was still shooting my best. That’s one benefit of these 5 shot groups. They don’t tire me as quickly.

Octane combo 10-meter RWS Superdome target
Five RWS Superdomes at 10 meters measure a long 1 inch between centers. When you compare this group to the one made by the Hobbys, you see that Superdomes are not suited for this Octane.

Now, for those of you who think I might have slipped up on the last group, I shot 5 Predator Polymag pellets next. They’re a recognized premium pellet, just like the Superdomes, and I’ve shown some great groups using them in recent tests. But not this time. Instead of the group stringing sideways, the Predator group were stringing vertically. Five went into 0.982 inches, so we won’t be seeing them in any future tests of the Octane.

Octane combo 10-meter Predator target
Five Predator Polymag pellets made this vertical 0.982-inch group.

If you have now decided that I’ve gotten tired and ho-hum, what’s so special about the Octane if this is the best that it can do — hold on! I saved the best for last. Actually, the Octane saved the best for last because the next group is the last one I shot on this day.

Crosman Premier
The 14.3-grain Crosman Premier pellet is sometimes the best pellet you can use in an airgun. And it is in the Octane test! Five Premiers went into a group measuring 0.245 inches between centers. It looks like only 3 pellets have passed through, but I did shoot all 5. This is very clearly and hands-down the most accurate pellet I tested in the Octane.

Octane combo 10-meter Premier target
Five Crosman Premiers made this beautiful 0.245-inch group. It was the last group of the test. Who says the groups open up as you go? This is the pellet for this rifle.

I already gave you the summary in the beginning of this report. Now you see the substantiation of what was said.

Several readers reported higher velocities than I got in the last test, and I was asked to change the breech seal. Well, I might do that, but frankly the rifle is shooting so nice right now that I don’t feel any urgency.

The Octane is unlike any gas-spring breakbarrel rifle I’ve ever tested. I wish the trigger was better, but it’s hard to argue with the accuracy or with the rifle’s firing behavior.

I will skip testing the rifle at 10 meters with the scope that comes in the package and go straight to 25 yards next time.