The Maadi Griffin .50 BMG Rifle
Posted: February 9th, 2024, 4:33 pm
Those of you old enough to remember the Shotgun News, a publication that is no longer in print but was rife with all manner of ads targeted at both the firearms industry and enthusiasts, will surely recall that it was a Siren’s song of temptation. Within those beguiling pages I found an advertisement placed by Robert Stewart hawking plans and barrel blanks for his single shot, bullpup rifle design chambered in the .50 Browning Machine Gun cartridge. He called it the Maadi Griffin. This was around 1995 before he started selling easily completed “kits” which landed Mr. Stewart, a convicted felon, into hot water with the BATF.
But that’s another story.
If I recall correctly, the plans cost about $150 and the barrel blanks (purportedly Walther) were about $100. Not terrible but it was 29 years ago when a hundred bucks still felt like a hundred bucks. And during that period of my life I worked in, and had access to, a machine/fabrication shop where we built heavy industrial machinery from scratch. Encouraged by my access to quality conventional lathes and milling machines, I thought: I’m pretty sure I can do this! So I ordered a set of plans, a barrel blank and began accumulating all the materials to machine and assemble the fearsome Maadi-Griffin .50 BMG.
The plans were fairly straightforward and accurate save for one glaring and potentially ruinous dimensional mistake on the receiver. I alerted Mr. Stewart to this glitch and it was rectified in subsequent publications. The materials used were the highest quality alloy steels and were certified by the steel maker as was all heat treating. I made modifications that I thought appropriate and these were generally to improve the aesthetics of the rifle. The grip assembly, for example, as detailed in the plans was an abomination of welded bent tubing. My improvement was a machined billet trigger guard allowing the mounting of a standard AR grip. The barrel blank was just that – a blank. It had to be turned, tapered and threaded on both ends.
Now, simply because one is capable of fabricating most of the components, doesn’t mean one should. I think Robert Stewart called for a completely inappropriate Harris bipod on this rifle but I fabricated the mount to accept an M60 bipod later replaced with one manufactured by Serbu Firearms due to it’s shorter length and ease of manipulation. The muzzle brake was sourced from Armalite. It was the brake they used on their production AR-50 rifle. Why reinvent the wheel, right?
As my project approached completion, there were a few tasks yet to be accomplished. Headspacing, for example, and how the heck was I going to mount a scope? When it came time to headspace the barrel, think Savage and their barrel nut – same concept. Mr. Stewart lent me some Go, No-Go chamber gauges that allowed for the proper headspace. I designed and machined the scope mount platform to accept Leupold Gunmaker bases. The bases are each designed to be flipped front to back in order to accommodate a wide variety of scope configurations and allow adequate eye relief. When everything was ready for final assembly I paid an expert to TIG weld where required because that was, and remains, out of my skill set. I had the rifle blued at a local gunsmith and mounted a Tasco Super Sniper 10X scope.
Like most projects, building this rifle essentially from scratch turned out to be far more time consuming and expensive than originally estimated, but after almost a year and a half of spare time work it was complete and rangeworthy.
The first rounds fired were PMC factory rounds. The first shot, I will admit, I undertook with some trepidation. I fired from the hip while facing away. I did that a couple of times until I was certain Robert Stewart’s design would not evacuate my skull. I felt pretty confident based on the materials and heat treatment involved that it would be safe but it can’t hurt to exercise a little circumspection. At any rate, the rifle has held together all these years and I have no reason to believe that it will ever fail. It does, after all, weigh in at over 35 pounds!
I have since developed handloads with both pull-down projectiles and powder as well as commercial components. 750 grain Amax projectiles and H50BMG will go less than one MOA at 200 yards. I haven’t had a chance to stretch it out yet but that day is coming.
But that’s another story.
If I recall correctly, the plans cost about $150 and the barrel blanks (purportedly Walther) were about $100. Not terrible but it was 29 years ago when a hundred bucks still felt like a hundred bucks. And during that period of my life I worked in, and had access to, a machine/fabrication shop where we built heavy industrial machinery from scratch. Encouraged by my access to quality conventional lathes and milling machines, I thought: I’m pretty sure I can do this! So I ordered a set of plans, a barrel blank and began accumulating all the materials to machine and assemble the fearsome Maadi-Griffin .50 BMG.
The plans were fairly straightforward and accurate save for one glaring and potentially ruinous dimensional mistake on the receiver. I alerted Mr. Stewart to this glitch and it was rectified in subsequent publications. The materials used were the highest quality alloy steels and were certified by the steel maker as was all heat treating. I made modifications that I thought appropriate and these were generally to improve the aesthetics of the rifle. The grip assembly, for example, as detailed in the plans was an abomination of welded bent tubing. My improvement was a machined billet trigger guard allowing the mounting of a standard AR grip. The barrel blank was just that – a blank. It had to be turned, tapered and threaded on both ends.
Now, simply because one is capable of fabricating most of the components, doesn’t mean one should. I think Robert Stewart called for a completely inappropriate Harris bipod on this rifle but I fabricated the mount to accept an M60 bipod later replaced with one manufactured by Serbu Firearms due to it’s shorter length and ease of manipulation. The muzzle brake was sourced from Armalite. It was the brake they used on their production AR-50 rifle. Why reinvent the wheel, right?
As my project approached completion, there were a few tasks yet to be accomplished. Headspacing, for example, and how the heck was I going to mount a scope? When it came time to headspace the barrel, think Savage and their barrel nut – same concept. Mr. Stewart lent me some Go, No-Go chamber gauges that allowed for the proper headspace. I designed and machined the scope mount platform to accept Leupold Gunmaker bases. The bases are each designed to be flipped front to back in order to accommodate a wide variety of scope configurations and allow adequate eye relief. When everything was ready for final assembly I paid an expert to TIG weld where required because that was, and remains, out of my skill set. I had the rifle blued at a local gunsmith and mounted a Tasco Super Sniper 10X scope.
Like most projects, building this rifle essentially from scratch turned out to be far more time consuming and expensive than originally estimated, but after almost a year and a half of spare time work it was complete and rangeworthy.
The first rounds fired were PMC factory rounds. The first shot, I will admit, I undertook with some trepidation. I fired from the hip while facing away. I did that a couple of times until I was certain Robert Stewart’s design would not evacuate my skull. I felt pretty confident based on the materials and heat treatment involved that it would be safe but it can’t hurt to exercise a little circumspection. At any rate, the rifle has held together all these years and I have no reason to believe that it will ever fail. It does, after all, weigh in at over 35 pounds!
I have since developed handloads with both pull-down projectiles and powder as well as commercial components. 750 grain Amax projectiles and H50BMG will go less than one MOA at 200 yards. I haven’t had a chance to stretch it out yet but that day is coming.