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RFQ: Custom Arca Rail

Yerman

Plastic
Joined
Jun 29, 2020
Hello everyone. New here and found this board after searching for someone that can machine a part for me.

I’m looking for someone out there that can make me a custom Arca rail. It will be 22.5” long, cut out of 1/2” thick steel bar, RRS spec dovetail, and 5 countersink holes drilled for attaching to another part. I’m playing around with Fusion and got everything drawn up to my specs so I can send over drawings. If anyone is interested, please PM me and we can chat about specs, price, etc.

I’d like this done out of some sort of steel that has the least amount of flex. I’ll rely on you to tell me if it should be some sort of stainless, high carbon steel, etc. There is going to be a lot of weight on this part as well so that is something to keep in mind when thinking about steel choices. Thanks and let me know what you think.

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Here are the tolerances on the dovetail...
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I can do it for $150. I'd suggest 4140ph for it, strong and it shouldn't flex. How much of a load is going to be put on it?
 
I can do it for $150. I'd suggest 4140ph for it, strong and it shouldn't flex. How much of a load is going to be put on it?

Thanks for the replies guys.

This is actually a part to mount a bipod on a rifle. It’s pretty heavy at 34lbs with a 36” barrel and a lot of weight out front.

My goal is to get my bipod out further to take advantage of the lever/fulcrum principal to increase stability and make small movements at the back of the rifle less pronounced on the muzzle end. We shoot these rifles to 2+ miles and I think it would help out a lot with the long distances we are shooting.

The bottom of the handguard has holes drilled for 1/4"-28 bolts so it's what I have to work with.

I currently have a 1/4” thick steel plate made by another machinist, but it’s got too much flex which is why I want to make it out of 1/2” material. I have a video of it flexing but since I can only post pics, I attached a screenshot from the video below. Hopefully you can see the flex in the picture.

y9OCJR1h.jpg
 
Hello Yerman

Im sure you have seen the "BipodeXt ARC II Picatinny"?

It would seem to fit your needs perfectly and it would also be easily detachable. it looks like it is the same manufacture as your bipod. Is there any other reason you want to go with the steel plate? Flip the width to thickness ratio and you'll see an increase in rigidity.
Anyways just throwing a couple ideas out there for you.
Cool project.
 
hi Yerman
i think you design is critically flawed
if you need to move your bipod out that far and don't want to mount on barrel for fear of changing the harmonics of the barrel
then i think you should consider a longer rail.
The design you have will flex no matter what materiel is used
just my opinion just trying to help
 
Well like I mentioned before you could go with a thicker cross section and just cut out pockets to lighten it. I’d say 3/4 and then I can machine out pockets all along the back reducing weight but increasing stiffness in comparison To a 1/2 bar
 
bad design
go thicker and go aluminum need stiffness not strength
best way would be to make an extension of the lower hand guard
to run all the way out to where you want the bipod flat bar
just isn't that stiff you need the channel shape get the stiffness.
 








 
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