Okay, so this should also work with a mid=length barrel shouldn't it? Since it's just the length of the gas tube that is different?
I just want to be clear on this since everyone is only discussing carbine and rifle length so far.

Yes, the gas tube is different lengths for carbine, mid-length, and rifle.  As long as the FSB is drilled out to the same standards as the typical .625 FSB, then any of those three should be good.  Someone please correct me if I'm wrong.

John, you can do your magic to handguards, pistol grips and buttstocks?  If all three are possible, then I might have to send a set to you as it would look pretty cool on a prototype.

Well, I don't know if I'd call it magic , but I can help you out.  I sent you an email.

John Thomas

Well then is it a form of Alchemy?

Which gun is that? Those hand guards look way different than the ones on #1 and #8.

Now that is very interesting. Is that from The Black Rifle?

I have a picture of #4 with different furniture and a darker upper. I wonder what the story behind that is.

I also wonder, how that bi-pod adapter is attached. It almost looks like a separate piece.

Hey everyone, if we were to have a bipod mount created, how would it be best mounted?  Set screw or something else?  Suggestion welcome.  I'm going to try to meet with Jess this Friday afternoon.  Keep the great photos and question/answers coming.

yeah the pic is from TBR..everyone should have a copy...lotsa' cool pics in there

I would also think it's a separate piece..have no idea how it's attachedto the fsb though as it says in the caption that it's not attached to the barrel




if I was to make a copy of the bipod mount, I would either make so it was split along the top and just run a couple of small screws through to make it a clamp-on, or just have it pinned at the same time as pinning the fsb. This would keep the fsb simple and allow each builder to choose on whether to install the bipod mount or not...personally I would not, as I prefer the smoother look of the barrel and fsb without the mount in place.

It seems as the original bipod mount is part of the FSB or welded to it. I would make the FSB seperate from the bipod mount. Then the bipod mount can be made on a lathe which would be simpler. There could be a threaded hole put all the way through the middle from top to bottom. Then the nub can be attached from the inside with a screw and the bipod mount could be attached to the barrel on the bottom with a screw like a low profile gas block.
Dustin

Here is a rough drawing I made. .950 is the minimum distance from the front of the FSB to the lip on the barrel. It will probably be longer than this if the end of the FSB is solid like a modern one. .850 is the minimum distance so that it would work with an M16 bipod. All of the other dimensions are best guesses. Anyway, the FSB and bipod mount combo would cover the entire gas block area no matter their final dimensions. All that would need to be done is turn the .575 part of the barrel down to whatever diameter it was on the prototype.



Dustin

I did a little mash up from some of the pictures I have. I overlaid #1 over #4 (which is more or less a regular AR-15).



The prototype FSB seems to sit about an inch and a half behind the "current" position. The barrel itself isn't that much thinner, it just appears to be because of the added length. You'll also notice that the handguard on #1 is no thicker than the slip ring on #4. The rest of the gun matches up perfectly with the exception of the butt pad. It's thicker than those on the later models.

We're either going to need custom barrels, or really long handguards.

You would need an HBAR barrel to do that. An A1 or A2 barrel isn't wide enough just before the end of the handguard to have a .625 gas block placed there. With an HBAR, the original gas port could be welded up or covered and a new one drilled back a little bit. This complicates things a bit.
Dustin

Why should it complicate things, all your doing is substituting one FSB for another ?
It's not an exact replica of the prototype but an approximation. I think it will still look pretty good using a prototype FSB on a modern pencil barrel as long as you can line up the gas ports, or is the difference in the length of the 2 FSB's so great that normal h.g.'s won't fit?

Since these were all basically handmade and not standardized production models there is bound to be variations.
So we have some leeway in our builds don't we?

You may build it the way you want. If I were going through the trouble of making custom handguards, barrel nut, FSB, bipod mount, etc. I would like it to be as exact as possible. Probably the same reason my builds use the correct style lowers and the correct finishes and probably the same reason I butchered a lower so an M231 selector plate would fit to it.
The repro FSB (if made) will work with any length gas system. If I and others want to custom make a less than rifle more than midlength gas to go with it, it doesn't concern anyone else. It complicates things for someone looking to make the build as correct as possible.
Dustin

The one on the bottom may be how it would look if you used a normal rifle gas system.
Dustin

I personally would use one of the in white pencil barrels already on the market, but others would be able to do as they please.  You guys are really bringing up some great questions and ideas.  Thanks and keep them coming.

I too, would most likely use a new, commercial in the white pencil barrel.  This brings up a question concerning location of the gas port and flexibility in mounting the front sight base.  Take a look at the pictures below.  Assuming the barrel's gas port is aligned with the front sight base, is there variability in the positioning by moving the entire assembly forward or aft and changing the location of the end of the gas tube in the carrier key?

I guess the bottom line of what I'm asking is... with the gas port aligned properly at the front sight base and barrel, are both scenerios in the pictures below operationally functional?  Do loose reliability as you move the assembly forward near the front of the key?

John Thomas

There would be no reason for the gas tube to move forward any. If anything, it would need moved back and all it would take is a pipe cutter to make it shorter. The gas port is right in front of the handguard cap, this is why the low profile gas blocks are so short. Like in my drawing above, the FSB/gas block could be as short as .950 - the width of the handgaurd cap and still cover the gas tube completely.
Dustin

pezboytate, I'm with you, but as a side note, will the rifle work as long as the gas tube is in the key or does it have to be in there to the factory depth?

Check my photos below (I didn't really want to let the cat out of the bag), but you can see this all is in the ballpark of lining up (based on the gas tube's roll pin hole), and if the fore/aft movement of the gas tube is slightly adjustable, as long as the gas port is in the same basic location on the prototype front sight base as it is on the real deal, there should be no reason to move everything very far from it's original place.  You can also see there is room to move the handguard aft a little more (closer to the upper).  These photos are with the gas tube positioned to the factory depth.

John Thomas

Those handguards certainly are long enough to use the standard rifle length gas. The ones on #1 might be shorter and are flush with the front of the receiver.
Dustin

This picture shows how the distance from the face of the handguard to the roll pin hole is about the same on both types of handguard.  It seems to me like the standard gas port position (basically) is the correct way to go.

I did some super cheesy photoshopping (because I don't know how to do that kind of stuff), but hopefully you'll see my intention.

In the photos below... The yellow line shows the alignment of the gas tube roll pin hole, then I narrowed the front sight base and overlaid it showing how the pin hole would basically line up (I didn't change the position of the yellow line from the first picture to the second).

I hope I haven't created more confusion than clarity.

John Thomas

04ZREX already stated that he would make the repro FSB compatible with current gas ports and gas tubes. The original had the gas port hole drilled up through the middle of the FSB where the sling swivel is. Current FSBs have the gas port hole drilled up through the rear of the FSB where the sling swivel is. The original was probably .5" or so from the rear of the FSB and the current is .25" or so from the rear of the FSB. As long as the repro is made to line up with a rifle length gas and your handguards end at the same location as with a standard FSB, then you will be fine.
Dustin

This is what I'm thinking, too.  This is enough to make my head hurt.

John Thomas

Aren't those AR-10 handguards? That would explain the length.

As far as this whole gas tube and port business, as long as the replica lines up with current specs, it should be good to go. We want to maximize compatibility with these without drastically altering the appearance.

Thus of us who want to be more faithful to the prototypes will need custom barrels turned anyway. We can sweat the finer points and beat things into place when we get to them.

They are Sudanese AR10 handguards, but the length seems to be pretty much right on the money (compared to the AR15 handguards) as you can see in my earlier pictures.  This is because the extra length is over the area where the slip ring would normally be... as shown on some of the original prototypes.

John Thomas

Dustin I wasn't trying to come off sounding like a smart alek, I am amazed by the amount of knowledge in this thread and I am learning lot's.
It's just that I haven't ever learned what you guy's take for granted. While I grew up and used an M-16 as a Marine it was almost 30 years ago and I only got back into AR's for my wife and daughters 2-3 years ago so I have been learning as I go along, again.

This is my first try at making something that look's like the pictures I kind of remember seeing back in the mid 60's when I was very young.
I appreciate all the information, the pics really help me understand.

Yes, the length of the handguard worked out just fine when I put this rifle together.  The only thing I had to change was to slightly elongate the gas tube hole in the handguard because the gas tube position on the FSB was slightly higher. YMMV.

Please count me in for a reproduction prototype FSB and bipod mount. I wouldn't mind if this rifle looked a little closer to that photo of #4 posted earlier.

That's a nice looking rifle you've got there. I must admit, I'm a bit jealous.

How is that hand guard secured? Just sandwiched between the FSB and the receiver?

Thanks. The handguard is very close to but does not touch either the FSB or the receiver. Last December I asked for help on how to do this and the Retro Forum came through. The thread is now in the archives here.
One of the suggestions I got was from whoopiewagon who thought a Quick Change Barrel Kit from MandA Parts would do the job. It did work as it is small enough to fit in side the handguard and allow me to make cutouts on the snap ring to hold the rear of the HG. The front is a tight fit to the barrel and the gas tube (see picture in post above).

The handguard is very secure. I cannot move it forward or backward and it does not have any desire to rotate. True I have not taken a hammer to it for a thorough test (Not very likely to ever happen ;-)), but in trying as hard as I can, by hand, to make it move it feels rock solid.

Interesting... my standard M16 barrel nut fits inside my Sudanese AR10 handguard.  It is extremely tight, but it does slide in there.  As you can see in my pictures (near the bottom of page 3 on this thread), I have mine butted up against the snap ring, but I know I may need to notch my snap ring like you did if I need a little more rearward movement of the handguard.

Thanks for the pictures and information.

John Thomas

Well, I guess I screwed up this week.  I went by The Rifle Shoppe to visit with Jess about him casting us a prototype FSB and they are closed on Fridays.    I never even thought to ask about their hours when I talked to Jess on Tuesday.  I asked him if he would be their during my lunch hour and he said yes, but didn't mention about being closed on Fridays when I said I would come see him at the end of the week.  Well, I'll catch him next week.  I'll keep you guys posted.

Wow.. When you actually see the pics of how it was done, It makes much more sense.  Very ingenious.  Nice job !!!!

No problem and thanks again for taking this on.  Sorry it didn't work out for you today.

John Thomas

I talked to Jess a few weeks ago and sent him some pictures but he has never returned my emails or phone messages. From what I've read on the net TRS can be pretty slow with specials so I'm not sure.......

I'm really as busy as I need to be at this point and it's hard to find time to pick up a new project. So if somebody wants to move on it, just say so. Not that I'm abandoning the idea, it's just that I don't want to hold up progress.

Heatnbeat, I'll mention your photos and stuff to Jess when I see him if you don't mind.  I want to help you anyway that I can as you and I as well as the rest of this forum would love to have some of these to go with our NDS-32 stuff.  If you will send me some copies of your pictures and any questions via email, then I will take them with me next week.  Ultimately, I want to have you mount one of these prototype FSB's to a barrel for me if your willing and provided we are able to get something produced on this quest.  

Okay here's another update.  I visited with Jess at his shop this week and found out more about what it would take to have a prototype FSB cast.  Now if I can remember everything he talked about.  Here's a list of things that must come together to make this happen.

1st) I must come up with $500 for him to make a permanent mold, he suggested that we not even considering going this route if we won't be making more than 25 of these pieces.  He felt that having someone machine the part would be more cost effective if we weren't producing large quanities.

2nd) I need to come up with a one-off piece to make the mold or give him drawings with very specific dimensions, unless someone has a prototype FSB we could use to make the mold.  He really would prefer that we come up with something that he can make the mold from.  He said to consider that the part will have about 1% shrinkage.

3rd) I need to find someone who is a machinist to perform the final machining necessary to finish out the FSB.

4th) He suggested having the part cast using 8620 steel, as this is the same thing that is used to cast past and current FSB's according to Jess.

5th) Once he makes the mold, it would be up to me to get with a foundry to do the actual casting.  He sends his stuff out to a foundry out of state.  He says that there are foundries that would do the work from an individual even if they don't have a business.  Apparently the foundry would keep the mold on hand and just wait for me to place orders.

What are your immediate thoughts?  I'll find a way to come up with the money, but I really need something to give Jess to make the mold.  Is there anyone out there who has a prototype style FSB that we could use to make the mold?

I'd be up for throwing $50 towards having a mold made.
I'd want a discounted FSB if they're eventually made.

First let me say thanks again for keeping this project alive, and I do appreciate your efforts.

I will offer my immediate thoughts... It is starting to sound like what Jess said may be true that we may need to look at having these machined.  If we are able to come up with enough guys to split the cost of the mold, (let's say $50 each from ten guys).  Then we have the cost of paying a foundry to cast the part (I have no clue, but I'll throw the figure of $30 each out there).  We still have the machining costs, which I assume would be drilling/threading for the front sight and detent, boring the barrel hole, drilling the gas tube hole and gas tube roll pin hole, and removing any casting flashing. (let's say that is $40 each).  Then finally the shipping costs to possibly three different locations ($12).  

Using those rough prices, this already calculates to $132 for a front sight base that has not yet been parkerized.  Personally I would pay this; but the price jumps quick if we don't get 10 guys to split the cost.  If we only get five guys to commit (and pay for the mold up front), the price then calculates to $182, and I I'll be honest... I can justify this to myself easier if it's closer to $100 than $200.  Can we get 10 guys to commit to spending $132 for an unfinished, untested front sight base?  Personlly, I'd be surprised.

All the above is also based on someone offering up an already finished prototype front sight base; which finding Bigfoot is likely an easier task.

So... since I'm sending out negative waves, and I really want to keep this idea alive, I would like to offer a suggestion.  I'll need someone with a machining background to help me out... I would think there are small companies out there that specialize in CNC milling speciality or test items; and are set up to CNC small batches and one-off quantities.  It seems like if such a place exists, we could split the cost of having five or ten of these made on a CNC mill, and I would think the price would be more reasonable.  Even if the CNC machinist charges us $1,000 for a batch of 10, we still come out way ahead.  

Is there anyone out there familiar with CNC machining?  I assume most of the cost is in the initial programming???  Do you guys think machining on a CNC mill may be the way to go if we can get five to ten guys to pay up front?

Thanks for yoru time,
John Thomas

You would need to find an original, that's not been buggered, first to make the mold from.

there are 3d model machines that can make a plastic model from just a set of drawings..just ask unclemoak, he's used one to do a barrel nut wrench, of his design, for a Knight's railed HG

eMachine shop. I've not used them, but they offer a free cad program. You design the part in their software and then you can get a quote based on that design and the materials used. I believe they do anything from CNC to injection molding. They may even do metal casting, I can't remember. They definitely charge less, the more units you order. I was looking at them in regards to making an Edgewater buffer. I haven't downloaded the software yet but, reading around their site and forums, they seem decent enough. Might be worth a shot.

As for molding, coming up with a prototype is fairly simple. The most likely process would be investment casting. They make a mold of your prototype (which can be made from anything) then the cast copies in wax, then form a ceramic mold around the wax. The wax melts out when the ceramic is fired, the steel gets poured in, then the ceramic mold is destroyed. Point being, you don't need an original FSB, you just need a stand in made from plastic, epoxy, wood, whatever.

That said, jntmjt1 brings up a good point. There's going to be a lot of finishing required for these parts. The price really might start to add up. As an alternative, the raw castings could be sold and we could finish them ourselves.

Just throwing out ideas.

I'm really swamped and don't have much extra time, but here's a little more info based on my exploration.

There are at least 2 ways to get the machining program done. One is to have someone draw it up on the computer and give the file to a CNC guy. One of our designers says it wouldn't take real long for him to model it in Solid Works. That would produce a file for the machining but only a picture to look at and evaluate. It is also not always apparent if there are flaws in the design.  The other way would be for someone to make a prototype of the FSB in whatever material they found best. It could be wood, plastic and body putty. Fluff the model out so it looks perfect,  digitize the model   and then send the file out to be machined. ( We have this neat little gadget at work that has a stylus that you run over the part and you click mouse to enter coordinate points, then the program plots the points into a 3D model.)

The second way would take more time but it would give a real looking FSB for everyone to look at and evaluate. Personally, I'm an old fashioned kind of guy; I like to hold a thing in my hand  and look at it, 3D pics on a computer just don't do it for me. The other thing is that a hand made model would have certain subtle "discrepancies" which I'm sure the original had too. I think it would look more like an early prototype and not like a computer generated space gun part. ( JMHO LOL!)

OK I gotta go, the machines in the shop are calling!

I'd love to do the prototype model, it's what I do at work. Problem is I know I won't get to it soon.

I'm willing to attempt to make the model... probably out of plastic or resin.  I'm reasonably handy with this type of work.  If it doesn't come out right, don't worry... I won't send forward a crappy model.  But, I'm willing to try to make one.  If I do, is there someone willing to take it from the model phase to the machining phase? (or at least look into the cost)?

Thanks,
John Thomas

Lost Wax method would be easy for a proto.

I know someone here on the forum found one at a gunshow back in 07.

I downloaded a copy of the emachineshop program and I'm going to see if I can come up with something, and if it looks decent I'll look at getting a quote.

I also downloaded the sofware.  I messed around with it for a couple of hours and I didn't get anywhere with it.  I don't really have very good computer skills.  Let me know if you have any luck.

John Thomas
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