Aluminum Air Tube for Marauders?

[kkarmical]

That looks really good!  Can't wait til you open up and provide all the details... Good job!

[USAFANG6799]

That looks really good!  Can't wait til you open up and provide all the details... Good job!

Can you imagine how well something like this would have sold given how well the MRod was received by all and having Crosman to back it up?

[ackuric]

That looks really good!  Can't wait til you open up and provide all the details... Good job!

Can you imagine how well something like this would have sold given how well the MRod was received by all and having Crosman to back it up?

If Crossman wised they could dominate the market...They should AT LEAST have this simple option in the custom shop, custom air tube, steel/alum/titanium, custom barrels, regulated/non, ect....SIMPLE yet would be bread and butter for Crossman. IMHO. They'd have overwhelming interesst.

[USAFANG6799]

That looks really good!  Can't wait til you open up and provide all the details... Good job!

Can you imagine how well something like this would have sold given how well the MRod was received by all and having Crosman to back it up?

If Crossman wised they could dominate the market...They should AT LEAST have this simple option in the custom shop, custom air tube, steel/alum/titanium, custom barrels, regulated/non, ect....SIMPLE yet would be bread and butter for Crossman. IMHO. They'd have overwhelming interesst.

So has Crosman lost it's MoJoe to take the MRod to this next level? Or will it take a separate entity to do this?

[Rocko]

Don't hold your breath waiting on Crosman to be "innovative".  They missed a good opportunity to jump in on small cal. bullpup market & pretty much thumbed their nose at it. They are more than happy to just supply Walmart with inexpensive spring guns instead.

[USAFANG6799]

So I guess what I'm asking is can someone take this design once the kinks are ironed out and bring it to market for the populist ?

[Rob M]

incredible weight savings, that totally changes the guns handling and general feel I'm sure

[ackuric]

Wanna hear something cool? The next mod brings rifle weight UNDER 5 lbs...yep...currently weighing in at 4.5 lbs, just need a few more details completed which ultimately should keep weight around the same...

          

[Rob M]

awesome , always figured it was possible , just no one took the initiative !

[ackuric]

awesome , always figured it was possible , just no one took the initiative !

My first goal was to match or beat the fx streamlines weight, just because it appealed very much to me, I figured for MUCH less cost I can easily do so while keeping it 'MURICA! lol...air tube cost was 150$, that makes for around 600$ with gun cost to get down to close enough weight to the streamline. I have other minor weight reduction mods that I won't go at length to list.

-Matt

[kkarmical]

awesome , always figured it was possible , just no one took the initiative !

My first goal was to match or beat the fx streamlines weight, just because it appealed very much to me, I figured for MUCH less cost I can easily do so while keeping it 'MURICA! lol...air tube cost was 150$, that makes for around 600$ with gun cost to get down to close enough weight to the streamline. I have other minor weight reduction mods that I won't go at length to list.

-Matt

Coming in at 4.5 - 5lbs is Outstanding, you're going to end up with a very nice build there, offhand shots are going to be way easier & even enjoyable.

[lennyk]

this is fantastic, I am sure there will be a lot of interested folks

[ackuric]

awesome , always figured it was possible , just no one took the initiative !

My first goal was to match or beat the fx streamlines weight, just because it appealed very much to me, I figured for MUCH less cost I can easily do so while keeping it 'MURICA! lol...air tube cost was 150$, that makes for around 600$ with gun cost to get down to close enough weight to the streamline. I have other minor weight reduction mods that I won't go at length to list.

-Matt

Coming in at 4.5 - 5lbs is Outstanding, you're going to end up with a very nice build there, offhand shots are going to be way easier & even enjoyable.

I think the marauder in my current config with a few tweaks can be brought down to 4 lbs even or possibly shy of 4 lbs. In this config it is 4.5 lbs assembled without air, if I replaced the steel rods with titanium and shortened em a bit, I would be right at 4 lbs or just under. We're talking weight that competes with p-rod folks! WOW!

[farmerjoe99]

Wow, that would be a game changer for the mrod, if these became available at a reasonable price or if Crosman would make them.
that is the #1 complaint about the marauder take that away and man what a rifle.
 

[shultz]

Wow, that would be a game changer for the mrod, if these became available at a reasonable price or if Crosman would make them.
that is the #1 complaint about the marauder take that away and man what a rifle.

Absolutely. I like my Mrod's, I just don't want to carry them very far

I'd be in for 2 air tubes if someone would start making them.

Matt, you may have just started a good thing for all us Mrod owners

[ackuric]

Wow, that would be a game changer for the mrod, if these became available at a reasonable price or if Crosman would make them.
that is the #1 complaint about the marauder take that away and man what a rifle.

Absolutely. I like my Mrod's, I just don't want to carry them very far

I'd be in for 2 air tubes if someone would start making them.

Matt, you may have just started a good thing for all us Mrod owners

I got my tube on amazon (was discounted @ 20$, normally around 40-60$) but I am sure there are better sources, the discount on this particular tube was too good to pass up. I certainly feel this modification alone brings whole new light to the marauder and am proud to partake!

-Matt

[lloyd-ss]

I've been using aluminum tubes for years and love them.  2024T3 is the only readily available aluminum alloy that is, IMHO, suitable for air tubes. But please, please, make sure you are getting 2024T3 for your air tubes and not some other alloy.  When you receive the tubing, it should have the mill identification markings on the outside, with alloy and temper, heat lot number,  applicable mil, fed, astm, etc, certifications.  This is an expensive alloy for a critical application, and a reputable supplier will provide you with a copy of the mill certs if you request them with your order.  They might charge you a few bucks for a small order, though.  If the supplier says, "certs not available," look somewhere else.

So the first thing is to make sure the 2024T3  mill markings are actually on the tube when you receive it.  If you are getting a short piece, there is a fair chance that you won't get the full string of markings on the tube.  Also, if you are sending this out to be machined, make sure to tell your machinist that if he accidentally scraps the tube, to not replace the tubing with something else he might have on hand. 

Strength and fatigue resistance is why you want to be positive about the alloy.   2024T3 is commonly referred to as an "aircraft alloy," because of its high strength and good fatigue resistance.  7075 is an even stronger alloy but not readily available as tubing.  6061T6 is very available but does not have the needed strength or fatigue resistance, although it is commonly used in scuba cylinders that are designed specifically for that alloy.

2024T3 is not as corrosion resistant as some other aluminum alloys, but overall, it is adequately corrosion resistant for this application.  If you were using it in a salt spray or corrosive environment, that's a different thing.  Aluminum is a very reactive metal and naturally forms an aluminum oxide skin that is fairly corrosion resistant in a household environment.  If you are concerned, you can have it alodined (a dipping process), or anodized (an electrolytic process).  I powder coat the outside of my tubes and leave the inside as-is, which is usually mirror smooth from the drawing process.   

The big weight savings is the major advantage to 2024T3 aluminum, but remember that it has less strength than the DOM (drawn over mandrel) steel tubing normally used for air tubes.  A 23" long M-rod tube, 1.25" O.D. x .095 wall, made of DOM steel weighs 36.3 ozs. The exact same tube in 2024T3 weighs only 12.1 ozs. BUT, it is not as strong as the steel tube.  Luckily, the M-Rod factory tube is way over-designed, so the same wall thickness is ok 2024T3.

But here is the kicker for the strength comparison. The 2024 aluminum is only about 75% as strong as the DOM steel.  And I am not saying to do this, but if you overfill a factory DOM steel tube to say, 4,000 psi, you are still within reasonable safety factors for the tube, the threads, and the valve screws, although you might see a  little puckering of the tube at the valve screws.    But you can only fill the 2024-T3 tube to about 3,200 to get to those same marginal conditions.  And if you screwed up and made the tube out of 6061-T6, you would be on thin ice at about 2,500 psi.  I am not saying it would blow up, but I am saying that you are not where you want to be with the safety factors. When I make a 1.25" O.D. 2024T3 aluminum tube I prefer going to .120 wall (the next available thickness), and that extra wall thickness makes it just as strong as the DOM steel tube. An accidental overfill is of no concern at all.  But then none of the fittings work anymore, and it holds 9% less air, so its a Catch-22. 

Lastly, let's mention cost.  The 2024T3 tubing is at least 4 times as expensive as the standard DOM steel tube.  Switch to a high strength titanium alloy (not all Ti alloys are created equal!!!), and the cost is about 10 times what the steel is.

Sorry for the information overload, but safety is number one on the importance list. 
If you are curious, search airgun lab on Youtube and look for the pressure test videos.  It took 16,000 psi for a DOM steel Disco Double tube (.875 dia x .065 wall) to fail, and I couldn't get a 2024T3 aluminum P-Rod double tube (1" dia x .095 wall) to fail at 10,000 psi. The tube subsequently had to be machined thinner to make it fail.  But bursting is only one of many possible modes of catastrophic failure.  Please be careful.

Very nice project!

[shultz]

Good read Lloyd, very informative

[ackuric]

Super good read! Thanks Lloyd. I indeed did have all the markings you mentioned on the tube which were marked very clearly with all the information you stated, I'm sure Lee verified them as well prior to working on the tube. He even observed a small void in the tube that was 1/8th in length but was able to keep it on an atmospheric pressure side of the tube.

I certainly don't plan on filling over 3000 psi on this tube. If I were to do it again and didn't get a discount on my aluminum air tube, I would likely just get titanium as the cost is just over 2x as much as aluminum yet you'd have endless amounts more of piece of mind and even more cushion for over fills.

The closest titanium tube to stock I can find is below, at .092" wall thickness vs .095" and 1.066" ID vs 1.06". 96$ + shipping. I paid 20$ shipped for my aluminum tube (not sure why they had this one piece discounted, was the last one available at the time) where as normally this aluminum tube goes for 40$. Although aluminum is quite a bit lighter than titanium so for the lightest possible air tube, the 2024-t3 is the way to go!

https://www.titaniumjoe.com/index.cfm/products/product-details/?code=TU:3Al-2.5V:1.250:1.066:0.092:SC


Here is the tubing I got:



It's shipped AND sold by Amazon so I am confident in the material being what it is sold as.

-Matt

[Killfire]

Would carbon fiber tubes be lighter and cheaper than titanium? For the shoulder stock not the air tube.