Canadian Airgun Forum

No problem, they are amazing barrels for airguns! I have a .457 that will do 8" at 200 yards with roundball. Accurate with 420 grainers as well

Look forward to the 9mm info and results. Great caliber.

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Walter

Merry Christmas to you and the missus Walter. I was wondering about the rifling on those liner,s. The rifling on my gun,s are not as deep and pronounced as the liner,s. Does this affect accuracy in any way? I,m just supposing, but it seem,s to me that more pronounced rifling would make for better accuracy, as there should be less slide by before the rifling start,s the pellet spinning. Of course I mean on the high power gun,s, as this slide by affect would be minimized on the non pal gun,s. more spin should mean better accuracy. Lothar Walther over comes this affect by adding more land,s. I,m just guessing about the slide by affect. I don't even know if it occur,s at all, but with that sudden push on the pellet, it surely must, even for a couple of inch,s. It would be interesting to see a glass barrel to study the dynamic,s of the pellet and rifling in super slo mo.

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Eun Jin Sumatra 2500 .22 cal
Hammerli Pneuma .177 cal
Diana 34 panther .22 cal
Ruger air hawk .177 cal
QB 88 .22 cal
Beeman silver bear .177 cal
Crosman 2240 .177 and .22 cal
Hatsan mod 25 .177 cal

the barrels I get from TJ are made with chrome molly steel, not from cheaper DOM steel, chrome molly is much better and last longer, harder to bend as well

part of why the barrels are so expensive, chrome molly steel is not cheap.

DOM is how it is made
Chrome moly likely 4130 or somesuch is what it is made of

So it can be 4130 DOM tubing that he uses
Not likely drilled stock

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Walter

technically you are correct, but when ordering steal, DOM tubing is a lower grade metal and is used for hydraulic tubing and other high pressure application, 4130 tubing, even tho drawn over a mantel is not sold as DOM tubing, go figure, at least that is the way it is with the places I get my steel.

Suplliers differ then...mine specifies tubing type and alloy..ie .... 1026 DOM...not a huge issue I suppose.

Any pricing information on these Stan?

And welcome back BTW.

Al

How it is sold does not affect how it is made and what it is.

4130 DOM it is

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Walter

Ok, I rarely jump in on debates such as this, but...........

Walter is right, period there is no "but"...................

Aero-Tec, you need to find a new steel supplier as the one you have seems to be feeding you a bunch of bull which could get you or someone else hurt.

DOM tubing is not a lower grade of anything but a manufacturing process, also known as seamless tubing.
Another type of tube is welded wall or seamed, of course we could also get into pipe which is another animal altogether.
Also another completely wrong statement is that hydraulic tubing is or would be of a lower grade material.
Think about that one for a minute, picture the front landing gear on a A380 and the DOM hydraulic tubing the oleo strut is made from.............
DOM tubing is always sold as such and to describe it as a lower grade tubing or metal is completely buttock backwards.
4130 is the type of material or metal alloy that the tubing is made from or as you call it the "grade".

Three really good resources that you might find useful are...

The BC Millwrights Manual - this is the industry teaching standard throughout North America
A copy of the American Machinery's Handbook - this is considered to be the "bible" for mechanics and machinists
Also a paper copy of the McMaster-Carr catalogue is a great reference .

These can be pricey but are worth it, you only have one set of fingers............

Grunt

I said Walter was correct, I also said that my suppliers and TJ, the barrel maker as well as his suppliers refer to DOM as a lower grade tubing and my suppliers say it is used for hydraulic tubing, I was going by what they say, I agree that technically DOM is a manufacturing process, but in some parts of industry it is also referred to as a lower grade steel tubing as well, when compared to say a 41XX alloy steel tubing.

it is something like saying I Xeroxed something meaning I copied it, but tectonically you can not xerox anything as xerox is a company not a process.

in engineering levels and more technical levels of industries they would never refer to DOM as a steel tube but as a manufacturing process connected to a grade of steel tube.

I am not and was not arguing with Walter, I was agreeing with him but stating what my suppliers and TJ suppliers refer to DOM as tubing, and your right technically there is no sure thing as DOM tubing. But both TJ and myself can pick up the phone and order DOM tubing, saying nothing more then I want 20 feet of 1 inch DOM and they will ship it to us, go figure.

this post is to clarify what I said and not meant to continue a argument, I am in complete agreement, just stating some facts as it pertains to my and TJs suppliers.

OK, I just phoned my supplier, if I order DOM tubing they will ship ASTM 1026 A513 steel tubing to me, they and others call it DOM tubing.
I would not make a airgun pressure vessel out of it, I would use 4140 for the pressure tube, cost more but is much better tubing.
would anyone disagree with using 4140 as the pressure tube for airgun?

hope this clear this up

Stan

Hi Aero -Tec,

Just reread my post and need to make a correction,
DOM is welded and not seemless.
The better quality tubing is seamless.
I need to learn to sleep before I sit down in front of this thing.

Grunt

Um... 4130 or 4140 should be fine - so long as it's seamless. Make sure you don't work harden it. The stuff is great for through hardening or case hardening - but for a pressure tube, I would think that you would want it for the toughness.

When ordering steel, you should be careful to tell them what type, what grade and how you want it heat treated - otherwise the steel vendors tend to dump their crap on you. Do you want annealed, normalized, hardened? Hot rolled? Cold rolled? 1018 or 4140? Or what about 12L14? O1? A2?

Before you buy though, do your math and make sure your thickness is sufficient for the pressures you are dealing with plus safety factor. Your weakest points are at your threads and at your mounting points. I know I'm flogging a dead horse here since the machinists here know what to look out for - but it doesn't hurt to reiterate for the newbies. Know the difference between tensile and yield strength.

Dave Quackenbush has some good info on steel selection on his website - probably a good read if you intend to make a pressure tube.

Machinery's handbook. Never leave home without it.

All that aside,

Bob, beautiful work - can't wait to see your next experiment. I gotta get me some liners now...

Well I just learned something.... .... I always thought that DOM tubing was seamless.... I just checked through the SAE numbers in the chart I always use for pressure ratings from Air-Way.com.... http://www.air-way.com/pdfs/spres.pdf

It turns out that the SAE J524 is seamless but the other numbers (J525, J 526, J356) are welded.... and they are all rated at the same MSWPs.... The thinnest walled barrel I have (the 9mm) would be good for ~3650 psi in 1010 steel.... so I'm not concerned in the least as that has a 4:1 safety factor built in.... Plus, the barrel I have is Chrome-Moly, so add another 50%....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!

Life is too short to be wasted worrying about the opinions of others.