Aluminum Sleeved Barrels

[comfisherman]

I have been scheming on making an aluminum tension barrel similar to the ones used by several 10-22 barrel manufacturers. I have a magnum research 17mach 2 barrel and love it, however the costs of a center fire barrel with the same technology is absurd. MR makes what appears to be a nice carbon wrap barrel, they just have lousy twist rates and caliber selection. This leads me to scheming on how i could do it myself, I am a fairly competent glass worker ( I am partners in a wretched glass 44foot seiner) but i don't think i could pull of a wrap job.

I shot a buddies aluminum sleeved 22 and it shot on par with my solid stainless barres, which got me to thinking. Could this be done with a center fire? I feel confident in working with aluminum and the tension sleeve idea is something i think i could pull off. I have a few questions and would like the input of those of you (pretty much everybody) who know more than I.

1. Is there to much barrel warp when firing a center fire say a 6x284?

2. Will expansion and contraction in temperature be a fairly large problem on say a 20inch barrel?

3. Would electrolysis be an issue between the ss barrel and the aluminum sleeve?

4. Would it be better to do a tensioned barrel like a volquartsen or a pressed on sleeve like a tactical solutions?

I guess ill start with those four.

 

[lazylabs]

Not to sound like an idiot but what's your goal?

Were you planning a glue type sleeve? I saw a 1.250 barrel with a 3" AL sleeve on a bench gun but it was only like 22" long. To me tensioned barreled setups seem to make a little more sense than a sleeve but I still have no world records so.....

 

[comfisherman]

I was thinking of taking a straight taper barrel blank and turning it down after the first six inches and pressin on on an aluminum sleeve. Kinda like a volquartsen barrel. The idea would be to get increaded stiffness without increased weight.

 

[Black Diamond 408]

I have thought about this in the past as others have. What might be the problem is the steel barrel will heat up pretty fast and the alum sleve will suck the heat from it, good thing yes. Bad thing will be the alum growing and contracting through out this process, how much i dont know.
If it were tensioned or not barrel movment may become an issue. It would be similar to a regular
barrel that was not stress relieved properly, they are not accurate. Im not saying it wouldnt work, i just havent seen any facts or research on it. I can see where it would work on 22lr type
rifles where heating would not be a big issue. I would check with a metalurgist and see what
the dynamics are of the alum in heat transfer and elongation. Its gonna get hot, carbon barrels get hot but the material is stable, metal is another story.

Best thing is to try it and do all the tests, then if it works you will have somthing to talk about.

Dave

 

[comfisherman]

Dave thanks for the response.

I think that the expansion and contraction would be problematic, I punched some specific heat numbers on the approximate alloy i have versus stainless, I don't think there would be any way to do a tensioned barrel without drastic tension changes.

I'm gonna have to inspect a tension barrel, I know the 22lr barrel of my buddies heats up considerably when we are ground squirrel hunting. I may have to find an alloy that does not expand and contract as bad.

 

[älg]

Lothar Walther is offering this kind of aluminium sleeved barrels in some cartridges like 308 and I guess 260 and similar. I don´t know if they are still experimental but I´ve sen a couple of rifles made with them, not shot them though.

I spoke with Pete Lincoln from Roedale P. and initially they seem to shoot as well as an ordinary barrel. So it can be done.

 

[Black Diamond 408]

maybe there is some hope for the project? What i was thinking was an alum sleeve glued into place with a tension cap on the muzzle end, maybe it needs to be installed with a snug fit and not to tight, or very tight to pull the barrel and keep it straight. Testing is the only way to acheive results.

Its better to try and fail, than to not try at all.

 

[RockZ]

I am about to take delivery of a 7WSM with an aluminum tensioned barrel.
I'll keep you posted.

 

[strictlyRUM]

I have done a couple of integral 22 silencers on rimfires. I use a tension setup. A rimfire stays in the barrel alot longer than a centerfire. The tension setup helps this. I use like materials though in my construction. I use a .030 precision ground stainless tube and a stainless baffel system. I tighten the crap out of it. I was thinking of a ingegral on a sporter weight barreled hunting rifle. This way you dont worry of POI changes or a real long obstruction in the woods. I can show you a picture of the last one I built and the baffel but it has since been destroyed to try other things. The form 1 thing makes it so. I have the current pistola under construction with the same outside tube using it under tenstion and then a ti compensator that can trade off for a screw on silencer. This way I can go back and forth on different guns. I just wanted to try it. I think it came out cool looking. Let me know what you think. Oh yeah the barrel was 6.75 then there is 2.3 of effective baffel. Makes the whole thing about 9 inches. Also I turned down the barrel to .5 inch and threaded the end for the baffel. The baffel screws on the barrel and pulls the barrel under tension against the shoulder on the end of the baffle. This pistol is actually lighter than the original 6.75 barrel setup by a ways. If you need I can find the other pics when I get home.

.

 

[Clark]

I have been an engineer for 30 years.

Bonding two different materials together [with different coefficients of expansion and expecting some heat transfer] is something that is done all time, but you have to know what you are doing.

I would start out by reading up on the subject.

My Majestic Arms 17M2 Lothar Walther steel barrel in an Aluminum shroud has terrible heat transfer. It does two or three holes touching and then sprays holes all over the target.
Maybe you can do better than them.

 

[Black Diamond 408]

Clark,
this is the problem that i thought that might happen when working with high heat calibers, unlike the 22 rimfire. My big concern was the expansion of the aluminum. I dont know how your
barrel was made, but most to date are not epoxied into place, they have an air void between the barrel and alum, the nut pulls the barrel into tension. But no matter i forsee problems with extended shooting like you said. If one was building a hunting rifle where 3 shots would prolly in all likely hood be the most you would ever use at one time this would be fine. The ultralight rifles with the pencil barrels can do this same thing, fire several shots touching, then the third and forth goes astray due to the extreme heating of the thin barrel. More than anything it was a project to see if it could be done sucessfully. ABS carbon barrels are proven to work and would be lighter using carbon over alum. Maybe later this winter i may still make one up just for conversation sake.

Thanks for your input, do you have pics of your rifle?
Dave

 

[Clark]

I know that when they bond things in electronics, they know the expansion range of each piece. They know what is bonding them together and it's range of elasticity.

The kinds of problems they have are:
a) The bonding material want to be thin for heat, but thick for stretching.
b) The bonding material choices have thermal conductivity at the expense of elasticity, i.e. the rubbery stuff is like an insulator.
c) You would like to have big parts to get something done, but may be only able to have short parts. If that is a problem over .1" with electronics, imagine the problem over 24" with a barrel. And anything that warps the barrel with heat, wrecks accuracy.

 

[James H]

Here is my first attempt at an aluminum tensioned tube.

I was experimenting here so I didn't true the receiver before installing the barrel and it was amazing how the bullets would walk right down the target as the barrel heated up. This one was a 7mm SAUM. I have since done 2 more the second in a 6BR and the third in a 6mm Creedmoor. I have not shot the last on yet but the 6BR showed enough promise to do another I abandoned the 6BR because it is a 10 twist barrels and I wanted to shoot heavier bullets than it would stabilize but it did shoot the 87 V-maxes well.


James

 

[comfisherman]

bingo james thats exactly what i was looking for, aluminum sleeve full taper no nut on a savage action. I'm intrigued once again.