gas spring | Air gun blog - Pyramyd Air Report

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

Posted on March 25, 2020 by B.B. Pelletier ↓ 38 Comments

by Tom Gaylord
Writing as B.B. Pelletier

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. read more

Determining muzzle velocity

Posted on October 25, 2017 by B.B. Pelletier ↓ 53 Comments

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

Diana model AR-8: Part 1

Posted on October 26, 2016 by B.B. Pelletier ↓ 46 Comments

by Tom Gaylord
Writing as B.B. Pelletier

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.

Big!

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.

Inexpensive?

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.

Sights

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.

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!

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.

Trigger

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.

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.

Summary

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

Posted on January 8, 2014 by B.B. Pelletier ↓ 72 Comments

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

Part 1
Part 2
Part 3
Part 4

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)

Optional:
• 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.

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

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.

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. read more

Octane combo from Umarex: Part 4

Posted on December 23, 2013 by B.B. Pelletier ↓ 104 Comments

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

Part 1
Part 2
Part 3

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.

Sight-in
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.

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.

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 read more

Octane combo from Umarex: Part 3

Posted on December 10, 2013 by B.B. Pelletier ↓ 59 Comments

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

Part 1
Part 2

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.

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!

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.

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.

Predators
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.

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.

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. read more

Crosman MTR77NP scoped air rifle: Part 4

Posted on December 3, 2013 by B.B. Pelletier ↓ 76 Comments

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

Part 1
Part 2
Part 3

Crosman MTR77NP air rifle

Today, I’m testing the Crosman MTR77NP scoped air rifle for accuracy at 25 yards. This is going to be a very different accuracy report, for I have no targets to show you. Well, there is one target, but it wasn’t shot with the test rifle.

What gives?
In the last report, I mentioned that I wanted to mount a different scope on the test rifle and test it at 25 yards. I thought the Bug Buster 3-9x scope would be a good one, and I also shimmed under the rear ring because the rifle was shooting low in the 10-meter test.

I thought the rifle would group about 3 times larger at 25 yards than it had at 10 meters, but I also hoped some pellets might remain tighter than that. What happened, however, was just the reverse. Instead of 3-inch groups I got 5- to 6-inch “patterns.” I won’t call them groups because not all pellets fired even hit the target trap. And when that happens, I stop shooting that particular pellet immediately.

Crosman Premier lites
First up was the pellet I thought had the best chance to do well — the 7.9-grain Crosman Premier. They had done well at 10 meters with just 2 pellets outside the main group. Had they held to my 3X size increase, they would have grouped into about 2.2 inches; but when the third shot landed 6 inches away from shots 1 and 2, and then shot 4 landed 5 inches from that pellet, I stopped shooting.

I checked the scope mount to see that it was still tight. It was, and I’m pretty sure this scope is a good one because it has done well in other tests on other airguns. So, Premier lites are out.

H&N Baracuda Match
Next, I tried some H&N Baracuda Match pellets. But they were no better. They hit the target lower than the Premiers, and 3 shots landed in about a 5-inch pattern. Then, one pellet missed the target trap altogether. I stopped shooting after that shot, but I wasn’t done with this pellet.

I got the Air Venturi Pellet Pen and Seater and deep-seated a couple Premier lites to see what affect that would have. The point of impact changed, but the accuracy didn’t improve. And when the third shot missed the trap, I stopped shooting Baracudas.

RWS Hobby
The next pellet I tried was the RWS Hobby, which gave such a nice, round group at 10 meters. Two shots landed together, and I thought we were on the right road; then the next shot hit about 6 inches away from them. The 4th shot missed the trap altogether, and I stopped shooting that pellet.

RWS Superdome
By now, I was in a quandary. Was it me or the gun or the scope? I went back to 12 feet from the target and confirmed that the scope was still shooting to the same point, then I went back to 25 yards and tried an RWS Superdome. I had confirmed at 12 feet that the Superdome would be on paper at 25 yards and the first shot was. It landed high, but in good enough position to keep shooting. The next shot missed the paper altogether and I don’t know where it went. That was it for Superdomes.

What to do?
By this point I was really shaken. My confidence was ebbing fast and I needed to end this session on a high note. So I grabbed my Beeman R8 Tyrolean and a tin of Air Arms Falcon pellets and shot a final group of 10 at 25 yards. This one turned out good, as I expected it would. That’s where today’s target comes from. It isn’t the best group I’ve shot with the R8, but it’s a darn sight better than I did with the MTR77NP. Ten shots went into 0.41 inches.

I shot this 10-shot group of Air Arms Falcons with my Beeman R8 Tyrolean, just to confirm that I still knew how to shoot. It measures 0.41 inches between the 2 centers farthest apart.

What’s next?
I need some time to think about why this rifle might be performing like it is. If one of you made a report like this to me, I would tell you to check the scope because that sure seems like what it is. But I did check the scope and found no problems. The one thing left to do is to crank the elevation down all the way and all the way to the left and shoot a group. If it tightens up, then it was the scope. If not, it’s either the mounts or the rifle.

A little tip
What I did with the R8 today is a handy tip to remember. Sometimes the problem is you — or you wonder if it might be. Shooting a good group with a rifle of known accuracy is the best way to rule that out.