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Posted: 10/9/2012 12:24:03 PM EDT
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I have a side project that I'm working on and I'm trying to track down a source for a gas block extrusion that has a quad rail design.
any idea on where I could go to buy lengths of this stuff? Probably need 24 inch lengths. Raw extrusion would be fine. I'll be anodizing later anyway. Here is an example of what I'm talking about. http://www.ar15-rifles.com/shop/images/DPMS-4-Rail-Gas-Block50681-684.jpg Any info would be helpful! |
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Plan on machining what you need.......IF a manufacturer makes that as an extrusion.......they spent a HUGE bundle on the dies.......and Having looked into existing extrusions as a source for some of my products several years back.........very doubtful you'll find a manufacturer that will part with the raw extrusion.....and the plant where the extrusions are made can't sell to you as the company that comissioned the dies owns the rights to them.
Thick wall aluminum tubing is available but not sure if it would be enough for the profile you are seeking. If you are gonna use it in a solid hunk......I'd just start with a rectangular block and drill it in a lathe.......and let me assure you that is gonna be a huge pain in the ass  The tooling will either be PROHIBITIVELY expensive or you'll have to make most of it.
Start with a rectangle .....center drill.......turn a round section out on the end and mount in a stready rest. I have a 18 inch 1/2 drill bit that I'd use......and I'd make a bearing block to mount on the ways to steady the drill bit and hold it true......and you need a long lathe....I have a 16 x 78 Sumitt I'd use....... If you are making a series of shorter pieces......then mill the outer profile.......and saw cut to length......face the ends and then drill and ream to size. |
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I see so many vendors that sell the same profile gas block that I seriously doubt that they all get custom forms extruded.
Machining from a billet is just toooo time consuming. I can buy picatinny rail all day long. Like forged lower blanks, I think a few companies produce almost all of them. |
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Aluminum as a gas block = failure. statements like this = wrong I tend to think Al can make a decent gas block as the barrel port is going to take most of the erosion due to redirecting gas and the small port diameter. The gas block is a straight path for gas and is much larger diameter and much lower pressure. I'll make one out off Aluminum for a 300 whisper and give it a try. Stay tuned to this thread in a month or so.... |
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Quoted: Quoted: Aluminum as a gas block = failure. statements like this = wrong You have a right to your opinion no matter how uninformed it is. Personally after 38 years of building (not assembling, building) ARs I can unequivocally guarantee that an aluminum gas block will fail. Maybe not right away, but it will fail, long before any other part of the gas system. |
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Aluminum as a gas block = failure. statements like this = wrong You have a right to your opinion no matter how uninformed it is. Personally after 38 years of building (not assembling, building) ARs I can unequivocally guarantee that an aluminum gas block will fail. Maybe not right away, but it will fail, long before any other part of the gas system. An unequivocal guarantee! You must have actual real world experience with aluminum gas blocks,then. Please do elaborate. No, I am not being sarcastic. |
| I have seen a gas tube glowing almost white hot under sustained fire.....by simple deduction the propellent gasses are hotter than the 1200+( conservitive estimate) or so degrees required to produce the color.....Aluminum melts around 1100 degrees......erosion is going to happen.....and where erosion is happening....failure is next. |
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I see so many vendors that sell the same profile gas block that I seriously doubt that they all get custom forms extruded. Machining from a billet is just toooo time consuming. I can buy picatinny rail all day long. Like forged lower blanks, I think a few companies produce almost all of them. You are probably correct.......BUT the "so many" vendors you mention aren't making them......they are buying them......and if you can find a company that'll make an extrusion die for a few hundred feet of product.....LET ME KNOW..... 
With a 4 axis machine properly tooled you could probably whip one of those blocks out of billet in 3.5 to 4 minutes of machine time or less.....or on a turning center with a bar feeder and live spindle tooling even faster......but if they are extruded....the dies were many tens of thousands of dollars to make and they belong to whoever comissioned the dies.....and IF you can find out who owns them.....you might be able to get them yo part with a few feet...but it is highly doubtful....just the way the industry works. If you can be a little more specific as far as how much of this you need.....and weather it needs to be in a solid bar......or can be in small blocks with the proper profile...I can recommend several machine shops that could do the work for you.Honestly...if you have acess to a manual milling machine and time that really isn't that hard to make manually. Just need a 3/16 enmill and a couple of 1/2 inch mills with a radius on the ends a couple of V blocks and a vise. I currrently have no CNC capability (it is cheaper to contract out my productin runs).....but if you are looking to prototype something......send me a non disclosure to sign and a print and I'll see what I can do........and if the prototype works and you want to go to production...I can suggest several excellent shops running form Georgia to Minnesota and down to Arizona and many points in between. And the picatinny rail sections you buy are most likely machined from billet.........I make it in lengths from 3 or 4 inches to 15 inches according to my needs on a manual mill......with a 45 degree endmill it is really no big deal. In fact I'm looking ar a Cincinati Horizontal mill to do things just like this.....with a few ganged cutters on an arbor you can machine a profile as fast as you can feed the material past the cutter. |
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Quoted: Nothing to be worried about....90% of what is available is steel.....so just make sure it is a steel block and properly installed you'll have no issues....Yankee Hill Machine make a wide variety and they are all quality products.... Awesome, thank you very much for the info. |
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Aluminum as a gas block = failure. statements like this = wrong You have a right to your opinion no matter how uninformed it is. Personally after 38 years of building (not assembling, building) ARs I can unequivocally guarantee that an aluminum gas block will fail. Maybe not right away, but it will fail, long before any other part of the gas system. An unequivocal guarantee! You must have actual real world experience with aluminum gas blocks,then. Please do elaborate. No, I am not being sarcastic. Of course I do or I wouldn't have made the statement. I have custom made GBs out of alumininum since before you could even buy them commercially. They work just fine and I have never had a "meltdown". I would not select this material for a military combat weapon where engagement duration is unknown or for some idiot that goes out and does continuous FA mag dumps. Aluminun gasblocks do not = failure except in very extreme cases of stupidity. As an experienced 11B, I can say that you do not want to use your weapon to destruction when in combat. Why do you think the military specifies maximum sustained rate of fire? Nothing last forever if used improperly and beyond design margins. |
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I'd have to agree that aluminum is probably not the ideal material for a gas block, but I have yet to see one fail.
I've been able to locate other extrusions for other projects. I could start with 2-3 feet. Just too much time to make it myself. I have an aluminum gas block that I got with one of my .22 conversion kits and it is definitely an extrusion. The hunt continues.... |
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Is it better to get a gas block with holes on the bottom so the set screws into the dimplings on the barrel or the ones that have the use of two clamping screws? Or is it personal preference? Thanks in advance. I prefer the clamp style......always found them to be more secure because of the ability to apply more torque to the larger screws. Quoted:
I'd have to agree that aluminum is probably not the ideal material for a gas block, but I have yet to see one fail. I've been able to locate other extrusions for other projects. I could start with 2-3 feet. Just too much time to make it myself. I have an aluminum gas block that I got with one of my .22 conversion kits and it is definitely an extrusion. The hunt continues.... Didn't say they didn't exist.......just said that you'll have a virtually impossible time getting a manufacturer to part with any.......I have several contacts in the industry.....and I'll ask around.......but I serously doubt I'll have any luck....do you specifically need a 24 inch stick or would 10 or 12 2 or 2.5 inch pieces work? And for a 22 isn't a gas block...it is a sight base...
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Quoted: Quoted: Is it better to get a gas block with holes on the bottom so the set screws into the dimplings on the barrel or the ones that have the use of two clamping screws? Or is it personal preference? Thanks in advance. I prefer the clamp style......always found them to be more secure because of the ability to apply more torque to the larger screws. Awesome, thanks for the info. I’m buying pieces for another build now. |
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Aluminum as a gas block = failure. statements like this = wrong You have a right to your opinion no matter how uninformed it is. Personally after 38 years of building (not assembling, building) ARs I can unequivocally guarantee that an aluminum gas block will fail. Maybe not right away, but it will fail, long before any other part of the gas system. An unequivocal guarantee! You must have actual real world experience with aluminum gas blocks,then. Please do elaborate. No, I am not being sarcastic. Of course I do or I wouldn't have made the statement. I have custom made GBs out of alumininum since before you could even buy them commercially. They work just fine and I have never had a "meltdown". I would not select this material for a military combat weapon where engagement duration is unknown or for some idiot that goes out and does continuous FA mag dumps. Aluminun gasblocks do not = failure except in very extreme cases of stupidity. As an experienced 11B, I can say that you do not want to use your weapon to destruction when in combat. Why do you think the military specifies maximum sustained rate of fire? Nothing last forever if used improperly and beyond design margins.  This is an equivocal statement. Since you asked, we were not talking continious mag dumps from machineguns in a combat environment. No kidding nothing lasts forever if used improperly, not even an anvil or a water cooled Browning.
In your 38 years of building ARs, you said you have never experienced a GB meltdown, but you unequivocally guarantee it will fail. On one hand we are civvie shooters on the range on a sunny day, and you imply heroic last stands as an 11B against raging hordes on the other. Apples and oranges here. Yeesh. |
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Quoted: Yes I have had a aluminum GBs fail. Most failures were holes blown out the side of the block in a SA guns at the range. Not mag dumps, not FA fire, not hot hand loads. There is also a number of pictures on this forum of the same thing.Quoted: Quoted: Quoted: Quoted: Quoted: Aluminum as a gas block = failure. statements like this = wrong You have a right to your opinion no matter how uninformed it is. Personally after 38 years of building (not assembling, building) ARs I can unequivocally guarantee that an aluminum gas block will fail. Maybe not right away, but it will fail, long before any other part of the gas system. An unequivocal guarantee! You must have actual real world experience with aluminum gas blocks,then. Please do elaborate. No, I am not being sarcastic. Of course I do or I wouldn't have made the statement. I have custom made GBs out of alumininum since before you could even buy them commercially. They work just fine and I have never had a "meltdown". I would not select this material for a military combat weapon where engagement duration is unknown or for some idiot that goes out and does continuous FA mag dumps. Aluminun gasblocks do not = failure except in very extreme cases of stupidity. As an experienced 11B, I can say that you do not want to use your weapon to destruction when in combat. Why do you think the military specifies maximum sustained rate of fire? Nothing last forever if used improperly and beyond design margins. This is an equivocal statement. Since you asked, we were not talking continious mag dumps from machineguns in a combat environment. No kidding nothing lasts forever if used improperly, not even an anvil or a water cooled Browning. In your 38 years of building ARs, you said you have never experienced a GB meltdown, but you unequivocally guarantee it will fail. On one hand we are civvie shooters on the range on a sunny day, and you imply heroic last stands as an 11B against raging hordes on the other. Apples and oranges here. Yeesh. Use what you want, I'll use steel. It is stronger, last longer and expands and contracts at the same rate as the barrel.  By the way, there was no hole in the gas tube in this failure. Difference in expansion rates allowed gas to escape and it found a weal point in the aluminum GB ( or that's the theory ) here's another one from the forum: http://www.ar15.com/forums/t_6_51/373618_Help___Hole_in_Gas_Block.html |
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Sorry for the long delay in responding, but I saved this thread on another computer.
Thanks! That is the kind of failure I've never heard of before, and that is a very light gas block to me, even in steel. I would have expected some gas cutting along the gas tube if there was any damage at all. I'll still go ahead and make that gas block in 7075 to fit a flip down front sight. Gotta make one anyways as the barrel diameter is odd - largest diameter I could cut from a 270 sporter barrel and still make 18". |
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