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montanatim · New Member

I thought I would try a targeted question as my last post did not net any answers to this.

In the world of piston seals I have read on this forum and others about factory seals that I assume are made of Nylon from what was said.
I read about Apex seals, and Tesla seals. I have read discourse on the attributes of various materials in the making of seals. I have found no one thread that a person new to this (ME) could find the best choice for their rifle.

I e-mailed someone mentioned on this forum as having the best seals trying to find answers. From what he's wrote in the past, apparently I did not qualify for an answer under his no customer service skills/grumpy curmudgeon criteria.

So here it is: What are the differences between the factory,Apex and Tesla seals anyway?

Is one truly better then another and is this assessment across the board or is it application specific?

Is this all there is available or are there other materials/manufactures that I have not discovered yet?

I do appreciate the help as I do not wish to be ignorant in this area.

Alstone · Moderator & Site Supporter

Piston seals is a complex subject, it depends on what type of rifle you are using, the power out put and calibre, most tend to use nylon or a composite of it, Teflon seals work very well in the right environment. But with all seals it depends who makes them as they have to conform to certain characteristics to perform well.

It also will help if you could say what type of gun you intend fitting the seal.

BTW welcome to Airgunhome.

Al

montanatim · New Member

Thank you so much for discussing this with me.

The rifle is a Crosman/Benjamin Titan GP. .22 advertised velocity 800 w/14.3 lead--900 w/alloy. Cheap gun from what I've read so far but I like it.

The thing that prompted me to try to find out about the seal question in the first place is; I went to look at the seal it came with after it did not come close to advertised velocity. The one it came with had a gouge down one side and I thought AH-HA! I ordered seals from Crosman and when they got here they seemed harder and smaller(by a couple thousands?) They defiantly fit a lot easier then the gnarled one.

I started seal research and my only other post included some of these questions in it.

I'm not a speed junkie and would be happy with 750 from a 14.3 pellet of more then just one make when the rifle box says it is supposed to do 800 (up to, I know) But why can't it be done with this rifle? Hence the seal questions.

At least if I put one in that is as correct as it can be then that variable is gone.

I still wonder about lube. When installing a new seal should I have used moly grease or something else and to H#@! with dieseling?

I also read something somewhere else that advocated maintaining some fractional amount of dieseling to keep velocities up but that sounds hard on the rifle and dubious at best. Your thoughts?

toadmyster223 · Senior Member

This makes me wish I could chrony my Titan. I don't know how fast it shoots, but I know that even at 50 yards, a pellet hitting a dove still sounds like a baseball hitting a mitt. Pretty satisfying (:

Alstone · Moderator & Site Supporter

Always be weary of claims made by airgun makers on velocity, most are over stated, if the gun is new then it could take a thousand pellets to run in and reach it’s maximum fps.

You could put a smear of moly behind the seal lip this will help to break the seal in, as for dieseling this is something you don’t want, you will break the spring or worse if it got out of hand, another thing about dieseling is that it will give you inconsistent fps which is no good for accuracy.

Hope it helps.

Al

montanatim · New Member

Thank you for the input, but the main question still remains.

Can anyone give a knowledgeable dissertation on the various piston seal materials with application in mind?

The ones your average person could order from somewhere ready made?

Surely someone on these forums has the knowledge. Not necessarily saying that "this one is the best" but giving the attributes of each for various applications and allowing the reader to decide which is best for them.

Alstone · Moderator & Site Supporter

On the Apex seal the parachute is nearer the edge than on the Tesla, What the material is I don’t know and the maker is not saying, but for shooting heavy pellets the Tesla seems to give better performance than an Apex.

There are dozens of seal makers and seals made out of different combinations of nylon, neoprene, Teflon and many more exotic materials. And if you believe each of the manufactures then their seals are better than anyone else’s

A lot depends on the barrel length, twist rate, spring power, pellet weight and fit in the bore. So if you want to get the optimum seal for your gun the try a few different makes, shoot a thousand pellets with each one and see which comes out best. Because if you ask 10 people which seal they like best you will get 10 different answers.

Al

montanatim · New Member

O.K. I understand the difficulties in the question.

I also think I read something about a way to keep the piston from slamming the end of the chamber, some sort of button or buffer.
I suppose this would cut down on the available air movement but it sounded intriguing. Ever hear of something like that? Do you guy's think it is stupid or a waste of time? Does such a thing even exist?

Robw · Veteran Member

I believe that the Tesla seals are fabricated from Durlin which is considerably stronger than the nylon and polypropylene used in most stock factory seals.

radar · Silver Status Member

Unfortunately, I can't add anything about seal material. I suppose it is proprietary engineering information by the seal makers. Keep researching, and you may find something useful out there.

As for stopping the piston from slapping the front of the chamber though, what normally happens is the piston stops just short of the face, bounces back off the air cushion a little bit, and then settles fully forward. This all happens in milliseconds during the time the pellet begins to move down the bore. Adding any volume, in the form of padding, in front of the piston will likely radically reduce velocity. Spring piston air guns use a relatively small volume of air to compress, and anything (including boring out the air transfer port to the pellet chamber) creates too much volume to allow the little bit of air to reach high enough pressure when the piston bottoms out.

Yes the 900 fps is probably determined by calculation from a 1000 tested rifles, one of which had excess oil in the chamber, and shot one, light weight alloy pellet close to 900 fps, back in 2002.

My own rule of thumb is to multiply advertised velocity by 0.8 to 0.85.
Granted, some higher end rifles like RWS tend to exaggerate less, and Hatsans tend to exaggerate little if any, and are stated with lead pellets.

What you need is foot pounds of energy. Velocity, by itself tells little. Excessive velocity makes pellets tumble inaccurately, anyway. Any given rifle comes in a range of power...typically plus or minus 1 or 2 foot pounds of muzzle energy, depending on manfacturing tolerances, pellet weight and bore fit, the state of the gun's lubrication and wear or break-in. They all need some break-in time to stabilize, more or less, what power range they will shoot with a given pellet.

To get a general idea, you can check chronograph numbers and reviews on Youtube, or some such, for your model.

On piston slamming again, one way to help alleviate excess slam, or bounce back is to experiment with different pellets until you find the highest average muzzle energy output. More output usually means less energy wasted inside the rifle by banging things around.