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Thread: Building the Maadi .50 BMG
12-24-2003, 03:18 AM #1
I was wondering if anyone here has actually built a Maadi Griffen bolt action .50 BMG. from the plans they sell.
Has anyone built any .50 caliber rifles out of any other plans ? I have the Gunmetal Designs book but have yet to build it.
12-24-2003, 09:17 AM #2
I built the STate arms swat 50, It takes the ma duece barrel or the aircraft barrel, and happens to be for sale.
12-24-2003, 11:21 AM #3
I have a Maddi-Griffin about 50% done from plans. It is pretty straight foreward. Started on a Bill Holmes 50 but didn't like the way it was turning out so I scrapped the project. Have a set of plans for the Gunmetal 50 but I don't think my mill is big enough to mill the bolt lug recesses in the receiver.
12-24-2003, 12:07 PM #4
I've built the Maadi...although with several design changes that makes it more appealing to look at.
Whats wrong with the Holmes plans that made you decided to scrap it ?
Anyone have any pictures of .50's that they have built ?
12-24-2003, 03:58 PM #5
Didn't like the trigger housing/grip, receiver tube seemed way out of proportion. The more I looked at it, the more clunky it seemed.
12-24-2003, 06:48 PM #6
How did you cut the opening in the receiver for the bolt? Started on one but got stuck on that part. I have the plans and the video for the Holmes,I like his method better.Surplus barrels have dried up,hate to spend $300 for a blank.
12-24-2003, 11:22 PM #7
On the Maddi receiver I stood it up verticle in the rotary table and used a very long 1/2" endmill. The Holmes barrel extention was pretty easy to machine. I will have to admit that part of the reason I junked the Holmes gun was that I wasn't happy with my own work as well as some shortfalls of the design.
12-25-2003, 01:27 AM #8
I cut mine on a dividing head. Rather than stand on my head trying to see how I could cut it, I cut my receiver in half so that I could get an exellent fit up to the bolt. I weld prepped each end with a 45 dergee weld prep and had a friend of mine that is a nuclear welder weld it up for me. I then machined the OD to the final demensions. By looking at it you couldnt tell it was welded. After I heat treated it, I had it x-rayed and particle tested for cracks. It came out perfect.
The reason for cutting the reciever was so that I could better control the cut. I didnt want any possible deflection with a long end mill, so with the shorter piece I had a more rigid set up. It worked out well. After machining the bolt to fit the reciever I then lapped both of them together for a near perfect fit. As a matter of fact, it took me longer to lap it than any other procedure to machine anything did. The result was a very smooth and tight fitting bolt with virtually no play whatsoever.
Not having seen any pictures of the Holmes design, is it easier to machine than the Maadi ? Got any pics ?
[This message has been edited by BobB (edited 12-25-2003).]
12-25-2003, 10:57 AM #9
I would say the Maddi is a bit easier to machine than the Holmes. The 3 lug bolt definitly took more work to mill and then fit. I never did get an extractor made that I was happy with. The shell holder bolt on the Maddi is much easier to cut.
Cutting and re-welding the receiver would be the way I would go if I were to build another. Just about impossible to see what is going on while you are making the cuts for the bolt lugs. I don't have a tig welder so anything the I don't feel good about welding with the mig gets farmed out so trying to keep that to a minimum.
12-25-2003, 12:48 PM #10
One thing about the Maadi plans is that the pistol grip design is atrocious. It uses a piece of flattened out pipe for the grip. I made an aluminum adapter to take an AR-15 pistol grip that I later changed out to an HK design,it looks much better I think. Pictures of it here...
I suppose that one could do the same for the Holmes design also. Id like to check out the design of it, are there any links on the net that I could look up ?
[This message has been edited by BobB (edited 12-25-2003).]
12-26-2003, 11:42 AM #11
Have been looking at options for using an FAL grip with the Maddi. On the Holmes design the trigger housing is also very clunky. Tried to modify an L1A1 lower to work with it but had some problems. Here is a pic of my Maddi project, have done a little since the pic was taken. I don't know of any links that have any decent info on the Holmes design. I do have the book but no way to scan the pages into the computer.
12-30-2003, 01:57 AM #12
Looks good. I think that the L1A1 grip would look even better than the AR or HK grip due to the more radical grip angle.
Be sure to post a picture of it when you get it done. If it looks good enough, I might just make one for mine.
02-07-2004, 06:51 PM #13
Where can I buy the .040 spring wire called for in the Maddi plan book
02-08-2004, 01:41 AM #14
If it is just piano wire, try a hobby shop.
02-08-2004, 01:42 AM #15
I used hardened music wire, you can buy it cheap in 3' lengths at a well stocked hobby shop that sells RC airplane stuff.
02-10-2004, 06:14 PM #16
Here are a couple pics of the beast so far.
The hose clamps are just to hold it together for fitting. Will start welding as soon as the parts get back from the heat treater.
Try to ignore the messy workbench!
02-10-2004, 09:45 PM #17
The grip design looks great. I like it.
Why so many threads on the barrel ?
Bipod is an interesting design. Looks a bit tall for a bench though.
Looks like its coming along nicely.Do you plan on bluing it?
Are you going to use the stock muzzle break ?
02-11-2004, 12:28 PM #18
The barrel is the same one I was using for the Holmes 50 that I was building but scrapped. Threaded it for a big honking brake that I made for the Holmes, it looked pretty good on it but looks kind of oversized for the Maddi. I will probably test fire it al least with the big brake and see how I like it. If I don't care for it then I may go back to the original Maddi brake design. Am set up to parkerize so that will be the route I go for finsh.