Thursday, June 30, 2011

The .50 BMG bipod

Been moving along real slow on finishing the .50, this constant 100+ degrees every day is really wearing me out. I have gotten a few parts rough machined for the bipod, but still need to do some final machine work and sanding to them before adding the springs that will hold the legs in the down position or in the folded-up position.

I wanted to make the bipod and the scope mounts at least look like I cared, but they're shaping up to be just quick and simple so I can Duracoat this thing and move on.
To start, I took some .75" square cold roll steel to make the legs out of. Nothing real special, but sturdy and capable of holding up a recoiling .50 BMG rifle. I drilled 3/8" holes at each end, one end to mount to tabs I would weld on the receiver, and the other end to mount to "feet" that would spread the weight of the rifle out a little. I wanted the whole assembly to be able to pivot freely, so the legs and the "feet" are hinged. I plan to drill sequential holes down the centerline of the bipod legs to improve the aesthetic value and lighten them up a little. I'll get to photos of the legs in a bit.

For the tabs that mount to the receiver, I had some 1/4" thick, 2"x2" angle steel that I cut at a 30 degree angle then cut an arc in the opposite side, so it would support the bipod legs in two planes.




The legs were bolted up to the tabs, then I needed to find a way to do some angle matching. The legs were at 65 degree angles to the ground, and I didn't want to just cut the legs to match the angle, because it really would not have given the legs much footprint to spread the weight of the rifle around. I had some 1.25" square stock laying around, so I cut 2.5" long sections of it off. I took the two cut off sections and set them up in my mill vise at 25 degree angles, then milled the bottom flat. Once that was done, I flipped the stock in the vise and slotted them with a .75" end mill to a depth of 5/8", then drilled them out for the legs to bolt in place.
The resulting legs and feet are pretty stout, and fold up and extend nicely. I still need to do my sequential drilling in the legs, round off all the sharp edges, add retaining springs, and add in some leg stops of some sort to limit leg travel both fore and aft.









That's all for now, I should have these finished up in a week or so. I have already started working on the scope mounts as well, but unfortunately my first attempt did not pan out, so I have started on a new mount. I will probably just weld a simple base on the receiver and bolt a weaver rail to the base so I can call it done. The Duracoat will be ordered this coming week if all goes according to plan, I have decided on a gloss black base with a red DuraPearl and clear. I hope this turns out in real life as good as it has in my head, but only time will tell. This weekend I am sandblasting everything in preparation, then once the scope mount and bipod are finally finished I will do my final welding, fill in any pits or gaps, then do the final sanding before adding color.

4 comments:

  1. Well still looks raw, but it's closer to accomplished toy with every post. :)
    Isn't a bolt handle a little longish? May be cut it for a while? And bend it down...

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  2. Yes, still looks very raw, but it will get better. :)

    I made a new bolt handle that was longer than the last one so I could get enough leverage to chamber a round. The headspace is REALLY tight and the longer handle helps.

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  3. Ouch. :)
    That makes the difference. But it's already AWESOME! :)

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  4. Thanks for the nice words. It will look better soon.

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