CZ858 - Machining for B&T magwell adapter - Questions

[krprice84]

Ok, so I've got some questions regarding machining for the magwell adapter. I might just end up getting a local gunsmith who comes highly recommended to do it for me, but regardless of that, I'd still like to understand exactly what needs to be done. Maybe it's something I can do myself on my friends' mill, but even if not, I'd like to understand.

On the drawings, the arrows and red text are mine (hope that's obvious...but figured I'd throw that out there).


Upper Drawing questions:

it looks like the red line is denoting metal that gets removed - it looks like you remove the little "corner" of metal, back to the red line. It also looks like the little ramp above the "corner" gets left completely untouched.

So to me, that looks like the ramp actually sticks out over the machined section, is that correct?

Or is the drawing simply not to scale?

Or do you also want to machine the ramp back so it's inline with the vertical section of the red line.


Lower Drawing questions:

The way the red line is drawn here, it looks like you trim back EVERYTHING (including the ramp, if required) back so that there is 63.6 mm of clearance. Is this right?

It also looks like, from the this drawing alone, that you would remove ALL material, and leave NO deck intact, but from the top drawing, there's clearly some material/deck left. Is this deck/material important? Is it important for it to be at exactly the right height, or is it just a "need at least 17.3 mm clearance?

When they say "R3", what do they mean? Is that just denoting a radius'd corner? Is R3 some sort of radius measurement, if so, what radius is that - 3 mm? I assume that would be a minimum, or no?


Photo questions:

So when you look at the photo, to me it looks like the second question in the "lower drawing" section above is mooted. It looks like you absolutely leave some material to form a "deck" there, and you bring back everything so the deck is 17.3mm from the bottom edge of the receiver, and 63.6mm away from the piece in front of the trigger area. Is that correct? You just want, when looking in from the bottom, a flat deck?

Sorry for all the questions - I am just confused when looking at these drawings (I'm not a machinist), but I want to understand what gets done here.

Thanks for any help

Photo:

 

[Steiner]

If your going to have someone do it, maybe send it to Wolverine Supplies? My friend had Wolverine do his and it works excellent. Since they've done a few conversion, they'll probably be aware of special details.

 

[krprice84]

The guy I might get to do it has experience doing a few of these. Like I say, I'm just more trying to understand it myself.

If it's really as simple as it looks like it would be, then I know I can do it myself. But I don't really feel right asking someone who does it for a living "hey, can you explain to me how to do this myself so that I don't have to get you to do it" - not really a kosher thing to say to a gunsmith who makes his living working on guns.

Not that I think he'd turn me away, and it's not even that I don't want him to do it. I just like working on my own stuff, and I like being able to say "I did this myself" instead of having to take it in. I rebarrelled my own M1A myself, with a barrel vise I made myself. I'm about to cut down my brand new Sako Bavarian butt stock to fit my length of pull, myself (yes, it's going to be nerve wracking, this is a beautiful stock). Just fun to do that kind of work myself, and rewarding shooting a gun that I know I did everything on.

Having said that, if it's the difference between having a functioning gun, and having one I worked on myself that doesn't function right, I'll take the working gun every day of the week, of course.

Any done this before, or anyone have before and after pics that are better than the ones included in the instruction sheet from Wolverine? Or info/advice on exactly what is cut and how much?

 

[lmar]

Machined Step - Notice it matches the magwell on the adapter



Magazine inserted into adapter with step machined



The milled section is simply a step that you can machine using an end mill.
The step has nothing to do with fitting the adapter itself.
The milled step is to provide sufficient clearance for the front of the XCR magazine to be able to fit up into the receiver.
Feed ramp is left unmolested.

This is why you can remove the adapter and use factory magazines.
The recess or undercut you are talking about already exists in the receiver.


R3 is an abbreviation for "Radius 3mm" (This means you would use a 6mm diameter end mill or equivalent 15/64 inch diameter).
Depth indicates maximum depth you should cut.
Length from the back of the mag well indicates how far forward the front of the mill should travel.

L

 

[rommelrommel]

Do you have mags that work with the adapter? I have ran into an issue that only certain LAR pistol mags will engage the mag catch.

 

[krprice84]

Awesome thanks all. I think I'm gonna do it myself. After I got the gun apart and the mag well l lined up, I see exactly what needs to be done from those photos Imar posted. Thanks dude.

Any chance you have a photo of the miles section without a mag or the adapter in? Just so I can see how far back you went?

As for the undercut part, my question was more, do you need to machine under the undercut too, or not that far? I am assuming not that far if you are using a standard straight end mill and not some sort of t slot or something like that, yes?

Thanks again for the help, I think I'm gonna set up tonite. I think I only have an R2 end mill though not R3, is that a big deal?

 

[lmar]

Awesome thanks all. I think I'm gonna do it myself. After I got the gun apart and the mag well l lined up, I see exactly what needs to be done from those photos Imar posted. Thanks dude.

Any chance you have a photo of the miles section without a mag or the adapter in? Just so I can see how far back you went?
Need to use measurement 63.3? to determine how far forward you need to go.



As for the undercut part, my question was more, do you need to machine under the undercut too, or not that far? I am assuming not that far if you are using a standard straight end mill and not some sort of t slot or something like that, yes?

Thanks again for the help, I think I'm gonna set up tonite. I think I only have an R2 end mill though not R3, is that a big deal?

R2 should be fine as there will be more than enough clearance for the top of the magazine.
Need to use measurement 63.3? to determine how far forward you need to go.