I'm getting there... bolt fitted. I just need to machine the ancillary stuff like trigger slot, scope mount hole, pressure relief hole, bolt release, etc.

I won't be doing a magazine cutout... this will be a single shot rifle.



Original thread: http://www.ar15.com/forums/t_6_49/466175_making_bolt_action_receivers.html

Nice.

Nice job!
What material,are you heat treating it your self. How did you broach the race ways?

Material is pre hard 4140. It does not need heat treating.

I broached the raceway by milling part of the raceway with the ejection port. Then I used an end mill to plunge cut the rest of the raceway and finishing it off with a file. It's not very precise but it works. Takes forever though.

Hardened 4140 hand filed !, my hat is off to you.
Have you cut the bbl. threads yet?

Yes... I found a cheap tap from China to do that with. It's slightly loose however because I had to chase the threads a bit, because it was off angle a little bit. I should have built a jig for this.

The stuff doesn't like HSS that much, carbide chews through it but it even dulls carbide too, so I'm machining it with surplus bits to save some money (new bits would be dull in minutes)

I just need to finish the tang, cut the trigger slot and drill the hole, drill a few more holes, and then profile the outer dimension to fit a Remington 700 stock. I don't have a lathe so I will most likely make a octagon receiver. I can just modify a stock Remington 700 stock to fit.

Hardened 4140 isn't that hard to file. Gunsmiths do it all the time anyways. Sure, compared to mild steel it's really hard to file or cut but with a set of good file it still works for minor dimensional change. Specifically the corners of raceway. If I had a shaper I could easily do it. 4140 isn't the hardest material to machine anyways... guys machine HSS, inconel (which is very difficult to machine) too...

Cutting the receiver tang. I changed the motor of the mill to a 1.5HP 3 phase motor. Now that 1 inch end mill cuts pre hardened steel with much less effort compared to the stock motor (which would often cause the speed to increase for no reason causing the end mill to get dull)

I envy your patience and determination.

Badass, dude.



What's it gonna turn into?

I'm going to put a stock 30-06 barrel on it. I dont know if I can use a standard unmodified stock because the receiver outer dimension won't be the same as a stock receiver...

Ah, so just a sporter, not an LR?

How do you intend on cutting the required camming surfaces?

What camming surface? Just a bevel where the bolt lug go? I do that with a hand file... the bolt locks up just fine in any case. I even tried it with a spent cartridge to make sure it works.

Yes I intend to make a sporter. Not going to make benchrest quality rifle here... the whole exercise is to make sure I know how to actually machine a receiver before I start messing with the 250 dollar broached blank. The blueprint I got still needs some work too, for example a slot down the tang for the bolt sear go to into (I studied my argentine mauser and it had one).

I tried looking for a camming surface on the argentine mauser and other than a slight bevel on the bolt lug and mating surface, I really couldn't find one.

Cam surface cut. I used a Dremel with a 1/8" end mill because it's the only tool that will reach that far down. Most dremel bits are way too short.



Receiver tang finished

Ok, it is functionally finished, but I need to refine the external dimension so that it would fit stock R700 stocks and accessories... I have to find a way to do this. So far I'm thinking of making it octagonal (I do not have a lathe)

Why not hog out the stock to fit?

Because it's not just the stock... it's the trigger, trigger guard, magazine, etc. designed to fit a R 700 that won't fit because the receiver's too big. I already had to mess with the outer dimension of the receiver to make the trigger work (I broke off the bolt release thingie, no way I'm going to be able to make a small cut under the receiver for the bolt release). I need to mill for a bolt release and the R700 external bolt release is so expensive. Maybe I should try and see if I can get a Mauser 98 bolt release to work...

Honestly the only problem with hogging out the stock I can see is the stock may not be wide enough...

Side profiled... I don't know if I should just mill the rounded part flat, or leave it in a squre-semi circle state. I've pre-fitted it to a barrel (did not tighten anything yet)

I will need to mill off a little bit of the front face in order to headspace it properly. Will need a headspace gauge.

Pre fitting action to stock. I used a milling machine to open up the stock R700 inletting to fit the oversized receiver... I know it's not 100% kosher but it's a cheap plastic stock (this is why I don't want to spend 500 dollar on an exhibition grade stock). The screw holes do not line up all the way so that means I will need to mill the recoil lug portion back to align the holes.

It's beautiful.

Rifle test fired, so far so good. I made up a load with 155 grain bullet, 45 grains of Hodgon BLC-2, and Federal primer. No pressure sign, no setback, no damage to the rifle, so I will say the build is a success. I have not made any proof loads because I'm doing this at an indoor range so I can't exactly tie the rifle to a bench and fire it with a string. The action itself is stronger than stock to compensate for not having specialized material or testing that Remington has... This load is based on Lyman 48th edition, but I used 1 grain less to compensate for military cases being slightly thicker.

So all that is left is to install a bolt stop (I will probably just drill and tap a hole where the bolt raceway is, and insert a bolt inside as a "bolt stop"), bed the action to the stock, install scope mount (I will use a blank weaver base), and blue the action. I have not figured out how to blue the action but Blue Wonder is promising. I also need to etch a serial number on it.

All in all this is probably the hardest "80%" project I ever done. Turning a bar of 4140 into a receiver, without the benefit of a broach or EDM, using a little ingenuity to get the job done. A EDM or even a better setup to drill the big bolt hole would have been nice but I still made a shootable rifle, so it proves it's not as complicated as people make it out to be.

The only thing I really need to fix is bolt cam timing. I messed up the back portion of the receiver so the extraction cam isn't really there... right now the bolt extracts nicely but if there were ever a stuck shell it may require a hammer to extract it. I'm wondering how to somehow add extra materials to the back of the receiver so I can attempt to file out an extraction cam.

I have to say with 100% conviction, I am very impressed, you did good!

Anymore done to it?

Sure. I just had a scope mounted and had it sighted in. The rifle is remarkably accurate though, more than I can be to be honest with you. The wide group is because my aim sucks but as you can see, it's perfectly capable of 1MOA and that's with a homemade receiver and stock Remington parts...