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| | |-+  Let me introduce... the RDB Aluminum m-lok handguard
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Author Topic: Let me introduce... the RDB Aluminum m-lok handguard  (Read 69982 times)
LeeMajors
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« on: July 21, 2017, 10:15:57 PM »

Hello all,

I was on here a few months ago asking about the RDB because the idea of a reliable bullup at a decent price was really interesting, so I went ahead and bit the bullet and bought the RDB.

LOVE the gun.

HATE the handguard.

So... I call Keltec and ask when the tactical handguard they debuted at SHOT will be released.  The answer?  "We don't know".  This year?  "Probably not, but maybe an announcement at SHOT this year". 

Well, that's crap.  So I'm making one. 

What follows are the 3D draft of our CAD file and the first 3D printed prototype.  It just got mailed to us today, should have it for evaluation in my hands Tues or Wed. 

What do you guys think?



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Clarke-Sensei
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« Reply #1 on: July 21, 2017, 11:03:32 PM »

Gotta say I love the look so far, and would say that it looks like a welcome improvement over the stock handguard
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Heavy
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« Reply #2 on: July 21, 2017, 11:06:06 PM »

Looks good. It might preempt my waiting for the rdb tactical. Is that bottom end flush to the end of the barrel, or will it end before the threads? Will you make a shorter version for the 16" barrel on the rdb-s and rdb-t?
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LeeMajors
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« Reply #3 on: July 21, 2017, 11:14:37 PM »

Thanks for the input!

As for the length, the bottom ends 1/8" before the threads, so if you have a suppressor that's threaded, it won't hit the handguard (although the inner diameter is 1.7" so it should fit most direct-thread suppressors on the market). 

As for shorter, we will certainly look at it, if and when the RDB-T and RDB-S come out, especially the -S.  If I had to guess, they'll be looking at our design saying "crap, we're losing market share" and will move faster with the RDB-T.  Happened when we were making ACR adapters and started talking about one for the SCAR (the only company that ever beat us to the punch). 

Unless they greatly improve on the mag release and bolt release mechanisms, I'm guessing they'll have a hard time getting existing owners of the RDB to jump if they have a good handguard like this.  Similar to the X-95 after the Tavor.  Many existing Tavor members just stuck with what they had and liked. 

We shall see.  One day at a time in the design world.  Maybe we'll look at the bolt release after we get this one in customers hands. 
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HBeretta
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« Reply #4 on: July 21, 2017, 11:17:05 PM »

looks really good to me LeeMajors!  Please keep us posted with new images etc...
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Hivedr.
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« Reply #5 on: July 22, 2017, 02:45:04 PM »

Hello all,

I was on here a few months ago asking about the RDB because the idea of a reliable bullup at a decent price was really interesting, so I went ahead and bit the bullet and bought the RDB.

LOVE the gun.

HATE the handguard.

So... I call Keltec and ask when the tactical handguard they debuted at SHOT will be released.  The answer?  "We don't know".  This year?  "Probably not, but maybe an announcement at SHOT this year". 

Well, that's crap.  So I'm making one. 

What follows are the 3D draft of our CAD file and the first 3D printed prototype.  It just got mailed to us today, should have it for evaluation in my hands Tues or Wed. 

What do you guys think?





Though IMHO aesthetically pleasing,  I can see an issues with the rail getting HOT fast caused by a thin barrel, aluminum hand guard and 60+ rapidly fired round = a lot of heat tranfered to and through the rail.  With no MLok positions on the bottom angled edges to accommodate addition rail covers to help combat the heat issues this could reduce the comfort of the rail and thus it's usablity. Might look at deleting the angled side "gill" type cuts (though cool looking) on the sides and go with more MLok slots. One thing is clear the younger Americans shooters like to have more vs less even if they will never use them.

Just my .02
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LeeMajors
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« Reply #6 on: July 22, 2017, 03:25:43 PM »

Quote
Though IMHO aesthetically pleasing,  I can see an issues with the rail getting HOT fast caused by a thin barrel, aluminum hand guard and 60+ rapidly fired round = a lot of heat tranfered to and through the rail.  With no MLok positions on the bottom angled edges to accommodate addition rail covers to help combat the heat issues this could reduce the comfort of the rail and thus it's usablity. Might look at deleting the angled side "gill" type cuts (though cool looking) on the sides and go with more MLok slots. One thing is clear the younger Americans shooters like to have more vs less even if they will never use them.

I think you're looking at it upside down.  Our design is meant to maximize heat dissipation, much more so than the non-vented plastic, which has been known to warp under continuous rapid fire.  

60 rounds isn't going to heat up the handguard.  600 would, but very few, if anyone, is going to go do that.

There ARE vents at the top 45's.  There ARE m-lok slots on the side.  The gill slots you are talking about are more closely spaced than m-lok's would be and there's more of them on the sides towards the bottom, and there ARE m-lok vents on the bottom.  

The top picture is what it looks like right side up.  The prototype picture is of the rail upside down.

As for more ways to mount rail covers, you couldn't fit a rail cover m-lok with a second row of m-lok covers on the sides/bottom angles.  There's not enough real estate.  

We did look at doing that.  The handguard was NOT aesthetically pleasing and you couldn't fit any additional rail covers on with as close as they were jammed together going around the handguard.  




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VASCAR2
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« Reply #7 on: July 22, 2017, 03:34:07 PM »

Will this hand guard free float the RDB barrel or does the RDB preclude getting the barrel free floated?
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LeeMajors
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« Reply #8 on: July 22, 2017, 05:21:31 PM »

There's really no way to do it without somehow extending the handguard back over the receiver area and drilling holes into it. 

The design itself has the two posts at the rear top that slide into slots, and the front secures to the gas block. 

If you eliminated the gas block mounting system, you'd have to really mold something to clamp around the front of the receiver then drill into it at least 4 places.  Not sure people would be up for that nor am I convinced it would be solid without further lateral reinforcement. 

Perhaps if the entire upper were made as a monolithic design, that would work, but Keltec would likely have to redesign the firearm for that. 
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Hivedr.
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« Reply #9 on: July 22, 2017, 09:04:21 PM »

Quote
Though IMHO aesthetically pleasing,  I can see an issues with the rail getting HOT fast caused by a thin barrel, aluminum hand guard and 60+ rapidly fired round = a lot of heat tranfered to and through the rail.  With no MLok positions on the bottom angled edges to accommodate addition rail covers to help combat the heat issues this could reduce the comfort of the rail and thus it's usablity. Might look at deleting the angled side "gill" type cuts (though cool looking) on the sides and go with more MLok slots. One thing is clear the younger Americans shooters like to have more vs less even if they will never use them.

I think you're looking at it upside down.  Our design is meant to maximize heat dissipation, much more so than the non-vented plastic, which has been known to warp under continuous rapid fire.  

60 rounds isn't going to heat up the handguard.  600 would, but very few, if anyone, is going to go do that.

There ARE vents at the top 45's.  There ARE m-lok slots on the side.  The gill slots you are talking about are more closely spaced than m-lok's would be and there's more of them on the sides towards the bottom, and there ARE m-lok vents on the bottom.  

The top picture is what it looks like right side up.  The prototype picture is of the rail upside down.

As for more ways to mount rail covers, you couldn't fit a rail cover m-lok with a second row of m-lok covers on the sides/bottom angles.  There's not enough real estate.  

We did look at doing that.  The handguard was NOT aesthetically pleasing and you couldn't fit any additional rail covers on with as close as they were jammed together going around the handguard.  






I based my input off 35+ years of shooting semi / full auto combat style rifles and your first CAD image not the 3D printed model. 60+ rapid fire rounds is were heat will start to be felt. Let alone 200-300 in an hour or two. It is a fact and widely know in the AR/AK/SCAR etc world when thin barrels are used under aluminum railed hand guard systems like those commonly sold today they get hot no matter how open the barrel is to ventilation. All I am saying is without the ability to install some kind of "shielding" be it via MLok or other method the heat issue will be worst with aluminum than the OEM polymer. For those that like to shoot lots of ammo be it run and gun games or just because it is fun there will be a issues with the aluminum getting hotter to the touch faster than the oem polymer.   

I love your design so please do not read my comments as negative in anyway. I have been waiting like other for a better fore end too.

 
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LeeMajors
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« Reply #10 on: July 22, 2017, 09:08:24 PM »

I appreciate the input.

The m-lok slots on the sides and bottom will allow the m-lok heat shields around the handguard for those who want it.

I'll do some testing and we'll see how hot it gets.  I don't think it'll be too bad, but we shall see.
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VASCAR2
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« Reply #11 on: July 23, 2017, 03:10:20 PM »

Thanks for the reply.  I thought the design would limit the ability to free float the barrel.  I still think a 6.5 Grendel RDB would make a great bullpup.
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LeeMajors
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« Reply #12 on: July 24, 2017, 07:54:39 AM »

Oh I do too, especially since an 18" Grendel barrel really is a must to maximize the cartridge's efficiency. 

I would certainly be interested in a $500-600 caliber conversion to both 6.5 Grendel and .300Blk
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Frostburg
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« Reply #13 on: July 24, 2017, 07:42:12 PM »

Obviously going from a polymer hand-guard to aluminum is going to create a weight differential. How much of a difference of weight do you anticipate there being?
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LeeMajors
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« Reply #14 on: July 24, 2017, 08:38:49 PM »

Very little.  The plastic they use is actually pretty thick. 

I'd be shocked if the total weight difference is more than a couple 2-3 oz.  I'll know more when we get the initial bids back from the machine shops.
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Frostburg
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« Reply #15 on: July 24, 2017, 08:59:18 PM »

Very little.  The plastic they use is actually pretty thick. 

I'd be shocked if the total weight difference is more than a couple 2-3 oz.  I'll know more when we get the initial bids back from the machine shops.
 

2-3 oz? A little extra venting or Mlok slots or what have you could eliminate that.
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Tj7
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« Reply #16 on: July 25, 2017, 12:17:32 PM »

The rail definitely looks good. I'd definitely be interested when this becomes available.
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LeeMajors
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« Reply #17 on: July 25, 2017, 04:44:37 PM »

Alright, I got home this morning at 0200 and finally got caught up with stuff I needed to do first.

Here are more pics of the prototype out of the box.  The weight on this 3D printed in reinforced Kevlar ABS plastic is 3 oz.  It's VERY sturdy in the front and rear where the cross-members are there for rigidity.  If, for whatever reason, we ever wanted to make these in this material, it's good to 400 degrees, doesn't conduct heat much at all, but we'd need to add a center reinforcement for strength. 

That said, since this is just a prototype, it should serve nicely.  Here's some pics before I sand it down.









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Pokem807
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« Reply #18 on: July 25, 2017, 08:39:23 PM »

Looks promising.  I'll be following development closely, and can't wait to see a finished product.
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Frostburg
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« Reply #19 on: July 26, 2017, 12:47:31 AM »

So what are you going to call it? It needs its own distinctive name.
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