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Matt.Cross

Bipodification - An exercise in (f)utility

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Alrighty, we're well overdue for another project thread so here we go!

Quite some time ago, I found a GG&G LCB-3 Bipod for sale on the interwebz and decided that I needed it for the MA TEN. At $125 it was a great deal because it was unused and came from a very reputable bipod manufacturer. However, I soon found it came with significant limitations. It doesn't pan or cant.

Now panning isn't a terribly important function in terms of the type of shooting that I do, I'm accustomed to setting up natural point of aim for each shot I take, so resetting the bipod isn't a big deal. Cant (tilt) function however, has proven to be a real deficit though for this bipod, as I found out on our first Fall Shoot and in some subsequent PRS matches.

Considering what it is and was designed to be, it's not a bad bipod by any stretch, it just doesn't do what I need it to. So this thread is all about the project to change that.

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What it is: 

LCB-3-Bipod_A.jpg

 

Primarily it's designed for larger heavier caliber guns. It's straightforward and sturdy, and not meant for the type of application I've used it for, so I'm acknowledging that right away.

So I'll include other pics here to further show what we're dealing with...

IMG_20180618_154455912.thumb.jpg.afa04c62c7928b3b23b789970104a4ad.jpg

IMG_20180618_154519156.thumb.jpg.3a8313d8667d79476f465f60f5c53acc.jpg

The heart of this bipod is a Y-shaped aluminum wishbone that joins the leg assemblies to the picatinny adapter, via 8-32 Torx socket-head screws and 1/4" nuts. Herein lies our first problem, a 1/4" with 8-32 threads isn't a standard size, and one of these little criminals was lost.

I called GG&G to see about replacing it, and it turns out they don't sell replacement parts, you have to ship your items in for repair. This seems a bit extreme, so I decided a project was in order.

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So first up, I ordered 1' of 1/4" hex stock from McMaster-Carr and drilled and tapped it for 8-32 threads. Cut it off in 1/8" length nuts and voila!, brand new replacement nuts without having to ship my bipod.

IMG_20180618_154554741.thumb.jpg.f0755e43daec3583d32712bd4ed6d41e.jpg

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So with the impossible nut problem out of the way, it's time to address the missing cant function.

IMG_20180618_154538803.thumb.jpg.25dc77644514a05161d9a52e879cabd2.jpg

IMG_20180618_154613629.thumb.jpg.6f531d8176a4ac46878867c3d1253e26.jpg

 

The top picture is the aforementioned upside-down "wishbone" that attaches to the rail adapter via the Torx cap screws shown in the lower pic, which were loc-tited in, by the way. None of the screws that need loc-tite have it, all the screws that don't need it have it. It's crazy.

The relationship between the adapter and the wishbone are why this bipod doesn't cant, if you check out the other bipods from GG&G, you'll see that their design in this area different. My project is to add inline tilt function to the existing hardware.

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So I disassembled the wishbone and adapter...

IMG_20180618_154806622.thumb.jpg.d90c241dbf2b6a3c7fe0c5dfe29c7ec8.jpg

IMG_20180618_154827552.thumb.jpg.2ad5637fa05dcc4e422148a1c23dbca2.jpg

Those are 10-32 Torx cap screws, spaced 25/64 apart. I determined this by re-installing the cap screws in the wishbone once it was disassembled, measuring across the outside of the bolt threads, and subtracting the thread diameter of one bolt.

So now I know what my center-to-center bolt hole distance needs to be. With this in mind I started on the bipodification.

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Now, I don't have pictures of all of the process, but it is essentially this;

I grabbed a piece of green scrap D2 tool steel (first mistake) and milled/surface ground it down to 3/4" wide, 3/8" thick, and 1 1/2" long.

It was drilled & reamed with a 1/4" bore lengthwise, and 4 holes drilled in the top, two sets spaced 25/64" apart.

IMG_20180618_155212088.thumb.jpg.e00531aac86e10c6c583f80410117fc2.jpg

One set of holes was threaded 10-32 to receive the Torx cap screws through the picatinny adapter. The other set was counterbored for 10-32 socket head cap screws for the wishbone.

IMG_20180618_154900211.thumb.jpg.a622bc622fef50b754737d5efff10648.jpg

The above pic shows the workpiece before the counterbores were put in, the pic below shows the shoulder bolt that will connect the two pieces when the workpiece is cut in half.

IMG_20180618_154917005.thumb.jpg.480f78be11314ba1c1d25cc99566ef44.jpg

IMG_20180618_154935725.thumb.jpg.1c080aba88015f3e267b225815ee76ea.jpg

IMG_20180618_154947488.thumb.jpg.fc49451ac158af1dc890200e191ebba7.jpg

That last pic shows the radius that is going to be cut on the bottom of the cant adapter.

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33 minutes ago, 98Z5V said:

I love this shiit...   :banana::hail:

It gets better, I actually screw up and it's documented....

IMG_20180618_165455715.thumb.jpg.b912df7adae886879b71448229d43c37.jpg

So I get the counterbores in (mistake #2), and right away saw that the 3/8" thickness, (and 3/4" finished length) on the workpiece was a mistake. There's not enough material between the counterbores and the 3 edges of the material as you see in the pics.

IMG_20180618_165449729.thumb.jpg.30ab1a7344782b9437011da44b701455.jpg

This wouldn't be a terrible issue, but the radius on the finished part makes this untenable. There's just not enough material there to provide the needed strength I want in the finished product. This is where I realized that this was just a prototype, and revision 1 was in order.

This was further confirmed when I attempted to finish the workpiece anyways, and the HSS slitting saw I was using self-destroyed when the tool steel work hardened. (AKA mistake #3)

Oh well, back to the drawing board, on to Phase Two. I'm in the process of doing a revised version, stay tuned.

 

 

*To be continued....*

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Just wrap it up, without the screws in it, with some ACE wrap and duct tape.  That should give you the flexibility without work hardening......

 

emoji's don't work for me anymore, so just imagine a smart-ass face here........

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48 minutes ago, bubbas4570 said:

Just wrap it up, without the screws in it, with some ACE wrap and duct tape.  That should give you the flexibility without work hardening......

 

emoji's don't work for me anymore, so just imagine a smart-ass face here........

 

Oh no, not gonna Bubba this next one. I've got more 1018 CRS than you can shake a stick at. Revision one is in progress.

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So, with another PRS match coming up at the end of next week, I decided to finish bipodification revision 1 this weekend. I decided on new dimensions and materials for revision one, 1018 cold-rolled being plentifully available and easy to machine. Semi-Final dimensions are 7/8" tall, 1" long, and 0.600" thick per segment. I also upgraded the pivot shoulder bolt from 1/4" to 5/16".

IMG_20180720_190449598.thumb.jpg.b02394b6a3370f50ce3b7eefa8b7265b.jpg

IMG_20180720_220230934.thumb.jpg.58b6a041d97d9007deca06a935d85bf5.jpg

A shot of the countersunk socket head cap screws....

IMG_20180720_220252628.thumb.jpg.9454014998d4a12f47071ce32fc0bb92.jpg

And finally, a view of the segments attached to their respective bipod components....

IMG_20180720_220404421.thumb.jpg.138266d61186e378679d48e0ac3fd76a.jpg

IMG_20180720_220515696.thumb.jpg.de34d4fffe5d325adeed407ce2409c61.jpg

 

Everything fits pretty well so far, I'm going to take a hard look at how much length and height I can reduce without a compromise of strength. All that's left beside that is to put the radii on the segments, bead blasted it, and paint it flat black.

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Ladies and gentlemen (honorific term used quite loosely)... 

WE HAVE CANT!   :banana:

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2 hours ago, 98Z5V said:

Ladies and gentlemen (honorific term used quite loosely)... 

WE HAVE CANT!   :banana:

Indeed, more than 90° of it!

Milling the radius the old-fashioned way...

IMG_20180721_205800438.thumb.jpg.82c9717e68c9ff258052dceb29657c37.jpg

Before sanding...

IMG_20180721_210030815.thumb.jpg.19604cb9c66f2b83dc0668cf4f7904fb.jpg

After sanding & before bead blasting...

IMG_20180721_210548062.thumb.jpg.2f99a67133562d644df475a07d47da96.jpg

After bead blasting & before painting...

IMG_20180721_211143259.thumb.jpg.de1c5909498deb1d400969949d7dcdcc.jpg

 

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3 hours ago, Armed Eye Doc said:

Matt's hitting the hard stuff.  I see the Cheerwine in the picture. :lmao:

Your modification looks great.:thumbup:

Thanks Doc, when the going gets tough, the tough switch to Cheerwine.

 

After painting.....

IMG_20180721_212338628.thumb.jpg.0fe3b823cc98f47f3340cd23fb3afc93.jpg

Pre-final mockup...

IMG_20180721_225716038.thumb.jpg.09bd7a76cfccdb44279c84c1de2698a9.jpg

IMG_20180721_225732769.thumb.jpg.242f64d9bb678436607d78d274243089.jpg

IMG_20180721_225857240.thumb.jpg.448776c2d95bd790a8a2c3b29c0bd94a.jpg

IMG_20180721_225933577.thumb.jpg.49781feaaa24afe3141b21a4b85f6701.jpg

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This guy is amazing?!?!

 

Although, some of our newer members might need a translator to get through that NC accent

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At public speaking engagements, I pull double-duty as his translator...  :laffs:

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