Piston seals: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Part 1

This report covers:

  • Importance of round air chambers
  • My best advice
  • Out of round pistons
  • The deal
  • Plain seals
  • Leather piston seal assemblies
  • Parachute seals
  • The PTFE seal
  • Last subject — seal materials
  • Piston rings
  • Summary

Today we will continue our discussion of the piston seal. This report was prompted by the comments of new reader Arvizu, who said, “ I noticed, too, that the seal plays an important role to define performance (sometimes small variations in diameter makes the difference). I would like to clarify that this is only my appreciation and limited experience with airguns.”

In Part One I attempted to show how a piston does its job. Arvizu’s question seemed to imply that he thought there might be an unlimited horizon for the piston seal, if only the technology could extract it. I tried to show that a piston is limited by the volume of air it compresses and improving piston seals is asymptotic. In other words there is a limit on the power that’s possible and we are now shaving small percentages as we approach that limit. To put it bluntly, we will never see the power of a spring piston system doubled by the seal. Never! read more


Umarex Trevox air pistol: Part 3

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2

Umarex Trevox air pistol
The Umarex Trevox is a single shot breakbarrel gas spring air pistol.

This report covers:

  • The test
  • Trigger
  • JSB Exact 10.34-grain
  • Sig Match Ballistic Alloy
  • RWS Hobby
  • Last test
  • Sights
  • Evaluation
  • Summary

Today we test the accuracy of the new Umarex Trevox air pistol. I like this pistol so far, so if it is accurate it is a best buy.

The test

I shot off a sandbag rest from 10 meters. I rested the bottom of the grip on the bag for most of the test to take up the pistol’s weight, though I did try it completely handheld. I will describe both holds as we go.

Trigger

The trigger pull reared its ugly head during this test. The pull is long and stacks up toward the end. I think the pull opened some of the groups a little. read more


Piston seals: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • Updates
  • Early leather seals
  • What’s next?
  • Now that you understand…
  • No magic
  • Don’t be depressed!
  • Leather piston seals
  • The better way
  • It’s all the same
  • Leather’s shortcoming
  • Summary

Updates

Pyramyd Air has shipped me the replacement Fortitude, so I will be restarting that report soon. Leapers is sending me a micro dot sight that I showed you recently. I wanted that to test on the Beeman P1 pistol that I stopped testing months ago, but now I also want to put it on the Chaser pistol and perhaps on a rifle or two. And yes, GunFun1, I am going to test the Gauntlet at 50 yards with the tightened shroud/barrel.

But today I want to talk about something different. As you are aware, this blog gets many new readers all the time. Often when they come in they have a question about a topic I have addressed in the past. If their question is easy to answer I will often just give them the links to the past report — if I can find it. But sometimes their question isn’t so easy to answer, and when that happens and I know that I have many other new readers who might perhaps benefit from it, I will write a special blog. Today is such a day. read more


Hy Score 816/Diana model 6 pistol: Part 3

by Tom Gaylord
Writing as B.B. Pelletier

Part 1
Part 2

A history of airguns

Hy Score 816
This Hy Score 816 is a Diana model 6 recoilless target pistol. This is the photo from the auction.

This report covers:

  • The test
  • Sig Ballistic Match
  • RWS Super Mag
  • Qiang Yuan Trining pellets
  • H&N Finale Match Light pellets
  • RWS R10
  • RWS Meisterkugeln
  • Why is this happening?
  • Proof
  • Summary

Today we see the accuracy potential of the Hy Score 816/Diana model 6 target air pistol I recently acquired. We had a good indication from the first group it shot.

target
This group of 5 Sig Match Ballistic Alloy pellets measured 0.338-inches. Shot at 10 meters.

The test

I shot off a sandbag rest from 10 meters. The Giss counter-recoil system allows for resting the pistol directly on the bag. Despite all my complaining, I shot with the pointed sight insert I showed you in Part 1. I did have a problem with it, but it wasn’t the sight’s fault and I will explain when I get to it. read more


Umarex Trevox air pistol: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Part 1

Umarex Trevox air pistol
The Umarex Trevox is a single shot breakbarrel gas spring air pistol.

This report covers:

  • RWS Hobby
  • Discussion
  • JSB Exact Heavy
  • Sig Match Ballistic Alloy
  • Firing behavior
  • Cocking effort
  • Trigger pull
  • Summary

Today we look at the velocity of the new Umarex Trevox air pistol. I said in Part 1 that this is a pistol to watch, so consider today’s report watching!

RWS Hobby

First up will be the RWS Hobby pellet. I’m going to show you more than just the average velocity today, because there is something more to learn from this test. Let’s look at the first 4 shots.

Shot………..Velocity
1……………..708
2……………..665
3……………..656
4……………..617

The Trevox started out dieseling strongly, like so many spring guns do when they are new. Veteran airgunners are used to this, but it may surprise a newcomer to the hobby. Let’s resume this string at shot 5. read more


Hy Score 816/Diana model 6 pistol: Part 2

by Tom Gaylord
Writing as B.B. Pelletier

Part 1

A history of airguns

Hy Score 816
This Hy Score 816 is a Diana model 6 recoilless target pistol. This is the photo from the auction.

This report covers:

  • RWS Hobby
  • Qiang Yuan Training pellets
  • Trigger improved
  • Sig Match Ballistic Alloy
  • Cocking effort
  • Trigger pull
  • I goofed on the trigger
  • Summary

Today we look at the velocity of my new/old Diana model 6 target pistol. There was a lot of interest in this gun last Friday — more than I expected. I really do feel fortunate to have acquired it. Now that I’ve learned that a reseal could cost over $200 with shipping, I really hope this one is doing okay! Let’s find out together.

RWS Hobby

First up is the lead lightweight, the RWS Hobby wadcutter. These are often the fastest lead pellets in an airgun, though my Diana model 5 actually shot a heavier target pellet faster. Let’s see what this pistol does. read more


Hy Score 816/Diana model 6 pistol: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

A history of airguns

Hy Score 816
This Hy Score 816 is a Diana model 6 recoilless target pistol. This is the photo from the auction.

This report covers:

  • The deal
  • Almost a PCP!
  • Sights
  • Model 6 variations
  • My pistol
  • Hold
  • Size
  • Power
  • Cocking
  • Trigger
  • The real world

It’s Friday and you now know what pistol shot that small group this week. It was a Hy Score 816 that’s actually a Diana model 6 target pistol. I had told you that I won this auction on Gun Broker. In fact, let’s look at what I said.

A seller had listed a Hy Score model 816 pistol for $119.99. Now, if you have listened to reader ChrisUSA, you have purchased your Blue Book of Airguns that has a manufacturer cross-reference table in the back. Hy Score was based in Brooklyn and did manufacture some airguns in the 1940s through the ’60s. They also bought airguns made by other companies that were marked with their name — not unlike business is done today. One company they bought from was Diana. I search Hy Score listings frequently, hoping to stumble across a model 807 rifle which is really — quick, someone tell me! That’s right, it’s a Diana model 27. read more