Revolver aluminum underlug cutter question

[Zip]

I want to make an underlug for a 7" barreled S&W 686 revolver using aluminum 6061 bar stock. I am a hobbyist and after some online searches am not sure which cutter I need to make the radius cut in the picture. (FYI: that underlug in the picture is from a Manurhrin revolver). I have the tooling for the straight wall cuts.

Found lollipop, ball end etc cutters...but not sure what I need to make the radius. The barrel in this area measures .721 side to side.
Thanks

 

[mhajicek]

You have options. You could drill, plunge, or bore from the end, or lay it down and lollipop. In production they would likely use a custom cutter of the right size; failing that, I'd surface it with an undersized lollipop.

 

[Zip]

You have options. You could drill, plunge, or bore from the end, or lay it down and lollipop. In production they would likely use a custom cotter of the right size; failing that, I'd surface it with an undersized lollipop.

Thanks for the response....I'm working with a mini mill and need to know which cutter I would need .ie size and source. I'd make the square cuts first (end to end) then finish up with a lollipop (end to end)...ideally in the .725 range?

 

[mhajicek]

Thanks for the response....I'm working with a mini mill and need to know which cutter I would need .ie size and source. I'd make the square cuts first (end to end) then finish up with a lollipop (end to end)...ideally in the .725 range?

When you say "mini mill", do you mean a Haas Mini-Mill? Or a small manual machine?

 

[Zip]

When you say "mini mill", do you mean a Haas Mini-Mill? Or a small manual machine?

Manual machine...been making a lot of high quality parts with it. Would like to locate some cutters (locally) like these.

 

[mhajicek]

Manual machine...been making a lot of high quality parts with it. Would like to locate some cutters (locally) like these.

Well, on a manual, you'll need that lollipop to be the exact same size as the feature you want to make, and will have no adjustability. I'd recommend doing it endwise with an offset boring bar; then you can size it in exactly how you want, to fit the mating part.

 

[wesg]

Get whatever size you can where the shank will clear at full width. And step it in at 5 or 10 deg increments.

 

[Zip]

Thanks...

 

[Zip]

Got it hogged out...grabbed a carbide wood working lollipop cutter and worked it slow until I got the correct radius. Fit's my same model revolvers great...can't do the finish work until the 7" barreled revolver is returned from S&W. The slab is 8.5" long...need 7"...may use the extra 1.5" a for poor man's comp.

 

[michiganbuck]

looks good from here. You could pul louvers in it and it would become a heat sink.

 

[Zip]

looks good from here. You could pul louvers in it and it would become a heat sink.

Oh..it's gotta a long way to to go!

 

[deltaenterprizes]

What is the purpose of the attachment? Being aluminum it does not add much weight which is the purpose of an underlug.

 

[Zip]

When shooting "NRA Action Pistol" I anchor the revolver against the side of the barricade. The flat sides of the underlug help lock the handgun into position (starts with 6 shots from the holster in 5 seconds...right and left side)...this pic is of a semi-auto with similar underlug.

 

[michiganbuck]

Seems like:

7.7 Barricade Event-All competitors must fire all stages in the standing position. All competitors may use the barricade for support. No portion of the firearm may rest against the Barricade for Open Modified, Metallic or Production Firearms Divisions. This event will be divided into four stages, two strings per stage, 6 shots per string, 48 shots; all shots will be fired from behind a barricade:

 

[Zip]

Seems like:

7.7 Barricade Event-All competitors must fire all stages in the standing position. All competitors may use the barricade for support. No portion of the firearm may rest against the Barricade for Open Modified, Metallic or Production Firearms Divisions. This event will be divided into four stages, two strings per stage, 6 shots per string, 48 shots; all shots will be fired from behind a barricade:

I compete in the Open Firearm Division (not in the Open Modified, Metallic or Production Firearms Divisions)

 

[deltaenterprizes]

Now I understand Ihave seen that type of match!

 

[Zip]

OK just waiting for some brass grub screws before final surface prep.

Any suggestions for a finish? It will be making regular contact with the barricade so I expect wear (shooter not a pretty face).. I have had real good luck anodizing (battery charger method) with color but any color will be subject to a lot of wear. Maybe just a straight anodize without color?

 

[MilGunsmith]

You could just bead blast and then renew it as it gets messed up.