Tag Archives: gas spring

Determining muzzle velocity

Posted on by ↓ 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

Introduction

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 … read more

Diana model AR-8: Part 1

Posted on by ↓ 46 Comments

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. read more

Octane combo from Umarex — trigger job: Part 5

Posted on by ↓ 67 Comments

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. read more

Octane combo from Umarex: Part 4

Posted on by ↓ 104 Comments

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. read more

Octane combo from Umarex: Part 3

Posted on by ↓ 59 Comments

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. read more

Crosman MTR77NP scoped air rifle: Part 4

Posted on by ↓ 76 Comments

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

Part 1
Part 2
Part 3

Crosman MTR77NP scoped air rifle
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. read more

Octane combo from Umarex: Part 2

Posted on by ↓ 61 Comments

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

Part 1

Octane combo
Umarex Octane gas-spring rifle combo.

Just a word
Befoere I get started with today’s report, I want to say something about what happened this weekend. Friday’s airsoft report got a lot of comments. Among them are several questions about the technology of the guns. And some admissions that people didn’t think much of airsoft before they tried it, then they found their opinions changed drastically. That also happened to me, so I can relate to it.

But all you who don’t care for the subject don’t need to worry. This isn’t going to become an airsoft blog. I will continue to report on it at a low level, but I know this is an airgun blog, and that’s not going to change. I want to assure the readers for whom the subject of airsoft is not welcome that we are still going to talk about pellet guns and BBs guns for the most part. I will write a few reports on airsoft now and then, and I trust they won’t upset you too much. read more