Machining an aluminum rifle chassis (stock)

[shermama96]

Here's a link to two of my early stocks:

http://www.hobby-machinist.com/threads/54r-aluminum-mauser-stock-project.33197/#post-312378

http://www.hobby-machinist.com/threads/mosin-rehab-project-2015.35842/#post-338008

You're going to find that you're going to need access to a rotary table for modern mag wells or going to need some special jigging to get the side tapers. Other than that it's all about basic milling and processing the cuts in the correct order so you don't cut away a surface you're going to need for clamping later on.

I previously stumbled upon your Mauser project, the finished Mosin is amazing, really love the contrasting aluminum with the OD. I'm still between OD and FDE, still can't decide.

All my tools are at school, but when roughly checking sides the Ruger magazine, which is honestly pretty janky, I found that the sides were parallel with no taper at all.

When the magazine is in the stock theres between 15 and 25 thousands of side to side play. Maybe I'm missing something in terms of mag-well taper, or did Ruger just decide the fit doesn't need to be perfect and just oversized the mag-well?

I have a long ways to go before I even start cutting anyway. I made a early stage CAD model last night, it turned out alright. I plan on adding some slots in the forend like the LSS chassis have. I'm finding I am pretty limited in terms of aesthetic features on the sides because of the slim wall thickness which is leaving me with a lot of empty boring space. Can't decide if I should increase my blank thickness or just keep it simple. I think I'm going to go with shallow flutes like in the first photo on my original post. If anyone is at some point interested in doing this project here are some photos of my CAD, shoot me a message if you are interested in the files.

 

[shermama96]

I just finished my 4th aluminum stock this summer. It' snot hard to do but a horizontal mill would not be my first choice. I cut my barrel channels with a ball nosed end mill with multiple XZ moves to cut the radius appropriate for the action. Depending on the type of rifle I'm building I sometimes remove more material to allow for bedding. On this last rifle I didn't use any bedding at all.

I typically make up a CAD drawing and form my cutouts to fit the components I'm using for the build if I'm not using original parts. On modern rifles where original parts are in order I just mimic the OEM inletting.

Also just to clarify, the horizontal mill would only be used for the convex shape that needs to be cut for the barrel, I plan on using a vertical mill for most of the shaping and the trigger and magazine wells.

 

[Holescreek]

In your cad model what is the length of the material you will need from end to end? My thought is that the forearm does nothing for the rifle except provide a platform for a shooting rest or a bipod and for efficiency the support needs to be as far forward as possible (and still fit on a shooting bench). I looked at alternative ideas to provide that support and settled on two steel rods with a forward cap. There's nothing wrong with the long aluminum handguards, they provide the same services but the expense and awkwardness of holding the longer blank don't make much sense for my tastes. Have you priced aluminum yet?

 

[shermama96]

In your cad model what is the length of the material you will need from end to end? My thought is that the forearm does nothing for the rifle except provide a platform for a shooting rest or a bipod and for efficiency the support needs to be as far forward as possible (and still fit on a shooting bench). I looked at alternative ideas to provide that support and settled on two steel rods with a forward cap. There's nothing wrong with the long aluminum handguards, they provide the same services but the expense and awkwardness of holding the longer blank don't make much sense for my tastes. Have you priced aluminum yet?

I did notice in both your most recent stock, and your earlier Mauser stock you used the two steel rods. I honestly just liked the look of the forward section. I was thinking about maybe making it as a separate piece to reduce the size of the initial blank and maybe making the trigger guard and the little nub the pistol grip screws into as separate pieces too. The overall length right now is just shy of 18 inches by 3.5 inches. The cheapest piece that size I found was 30 bucks plus 20 shipping, that damn shipping always gets ya. Now that you mention it, the more I look at my model the less like it, maybe it's back to the drawing board for now. Thanks for all the input by the way, much appreciated.

 

[Holescreek]

The two rod system on the Mauser was originally so I could make modular forearms to slip on and off just like the modular butt stock. The Mauser was supposed to get a detachable folding stock as well but other projects pushed it aside. After shooting it I decided that I really liked the balance with the rods. I used the same concept on two other builds but made the rods much smaller in diameter.

Where did you find a piece of 18"x 3.5" x 2" 6061 aluminum for $30?

 

[shermama96]

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The two rod system on the Mauser was originally so I could make modular forearms to slip on and off just like the modular butt stock. The Mauser was supposed to get a detachable folding stock as well but other projects pushed it aside. After shooting it I decided that I really liked the balance with the rods. I used the same concept on two other builds but made the rods much smaller in diameter.

Where did you find a piece of 18"x 3.5" x 2" 6061 aluminum for $30?

seems to be the cheapest I can find it. Because the rifle is so short with a relatively small action, I wanted to keep the stock pretty small as well. My design is using a 1.5 inch thick piece instead of 2 inch. Maybe that's why the price seems so cheap to you.
http://www.discountsteel.com/items/6061_Aluminum_Flat_Bar.cfm?item_id=133&size_no=116#skus

 

[Tozguy]

Are the CAD drawings in post no. 11 made up for the Ruger receiver? I do not see any V blocks and there seems to be a recess for a Remington style recoil lug. Could be me not reading the drawings properly.

PS: Your smooth, simple, clean design works for me.

 

[shermama96]

Are the CAD drawings in post no. 11 made up for the Ruger receiver? I do not see any V blocks and there seems to be a recess for a Remington style recoil lug. Could be me not reading the drawings properly.

PS: Your smooth, simple, clean design works for me.

Thank you I appreciate that. The blocks aren't in the design, I only included the pockets for the v-blocks at the correct height, I changed the layer color so you can see the contrasting shadows better. You can see the v-block pockets in front of and behind the magazine well.



I also extended the forend, it seemed disproportional, and then added some slots mostly because they look cool.

 

[Tozguy]

Ah, if the OEM V blocks can come out of the plastic stock then that's the way to go.

 

[Holescreek]

The whole stock will be made out of aluminum. Why would you want to use parts from another stock instead of machining them in solid square and level?