Homemade .50 BMG rifle
The .50-Caliber Rifle Construction Manual written by Bill Holmes was published in 2002. The Amazon customer reviews have criticized the book for its poor drawings and complex construction techniques.
A guy names “mxwelch” on YouTube has build a working .50 BMG rifle based on Bill’s book. To simplify construction he used an M2 maching gun barrel which he cut it down and re-chambered, instead of building his own, and made the rifle single shot instead of a magazine fed repeater.
The total monetary cost was $400 which includes the M2 barrel and chamber reamer rental. It took over 25 hours of shop time to build!
It weights 34 lbs and can shoot 1.5 MOA.
If you’re going to build a .50 caliber make sure it is within spec, with the right material, and the headspace is solid.
Of all the calibers the .50 caliber pose the highest risk of getting killed if it goes KB! Handgun KB! rarely results in any injuries. Rifle KB! can cause injuries but rarely death. .50 caliber KB! are nasty.
I remember one time a poster posted on a gun forum a while back (over 10 years). His friend got injured (probably dead. I didn’t fellow up on the post) when his friend .50 caliber single shot went KB!. The bolt itself broke lose from the receiver, went through his chest, and log into the wooded cabin 10 feet behind. That is f*ck up.
I’m not saying to not build or own one. Just make sure nothing is amiss when you pull the trigger.
I think the moral of that story is that if you are not able to properly build a the bolt locking lugs and a gas escape system, you should not be building a rifle, .50 BMG or not.
It’s good to know that Bill Holmes isn’t completely full of crap, but is there any proof of the general quality of the rest of his material? If it’s workable then it’s a goldmine, but if this is just a single lucky case then it’s a land mine.
The bolt was lock into place when the guy pulled the trigger. The metal failed to contain the pressure. It was not a home build .50 caliber. He bought it brand new however I do not know how many shot it had before it went KB!. As far as I can remember, he was an experiences shooter.
>>It was not a home build .50 caliber. He bought it brand new however I do not know how many shot it had before it went KB!. As far as I can remember, he was an experiences shooter.<<
Bullshit. It was homebuilt by someone and they skimped on the materials or the design was crap. There is no excuse for such a thing to ever happen.
And no production weapon would ever fail in that manner.
[RAVNEV]
Regular Army, VietNam era Vet
Howdy all. I had no idea I was famous until I stumbled on this.
The book has some sloppy designs on certain parts of the weapon but as far as safety is concerned it’s solid. The CUP pressures generated by this round are more than contained by the materials used. If anything the material thicknesses are overkill but better to be safe.
Of course if you substitute something like aluminum for the barrel extension or bolt then you really shouldn’t risk contaminating the gene pool anyway.
this may be to late to matter but i ran the math on it.
Stress to failure
sfail = Fs/As(note1)
so…. sfail = 135,000 / 1.125 = 120,000psi on the homes design with ASTM 4140 @ 30C rockwell
proof/test loads for 50bmg is 54,923 PSI(note2)
so…. 54,923psi * .804in(pi R^2) (rim dia.) = 27884.0506#
so if i had to make a guess with out any details i would say that their must have been a problem with the heat treat.
note1 http://www.homepage.montana.edu/~uessc/esci450/ShearStrengthCalc.html
note2 http://en.wikipedia.org/wiki/.50_BMG
ROCKWELL HARDNESS 4140 YIELD STRENGTH PSI
20 C 83,500
22 C 87,000
30 C 135,000
34 C 148,750
37 C 159,000
42 C 178,000
46 C 195,000
49 C 211,000
The Holmes design IS a single-shot, not magazine fed. Holmes specifies the materials to be used to safely make a rifle. The general consensis seems to be that he deliberately made some of the measurements and such a bit off, so someone not experienced enough to make one would not be able to, but an experienced machinist would catch them. There have been a number of rifles made to that design, with no problems.
who said anything about a magazine? yes the way it is shown in the book is a single shot bolt action. in his book “a master gunmaker’s guide to building bolt-action rifles” p27 ( isbn 9781581604207) he shows a design with a magazine. but a design is nothing more then guide lines to go by.
hello to all people:
i say that rifle its very complex to make and requires a specials machines (except the twist). we need think more simply! that no more “homemade”!
Pistolero what are you talking about? the Holmes design is very simple. no “specials” machines are needed. you can do all the work on a normal mill and lath. can even do most of the work on table top machines.
“we need think more simply! that no more “homemade”!” -how simply do you want? you cant make a sub MOA rifle with a dremel tool and drill press. every gun maker has to have a mill. sorry cant get around that. you can get around having a lathe but it takes much longer to get the same things done.
i would suggest you go in to a harbor freight and have a look at some cheap machines. maybe your should have a look on mcmastercarr.com too. they sell the tubing you need for the holmes design. be sure to get 4140 and not something cheaper.
one more thing
http://action_enterprise.tripod.com/FiftyPro.htm
its worth a look.
just go slow and dont get ahead of your self.
its really not that hard.
To keep it simple…
If you have the time, talents, and equipment build your own
If you can afford it… buy one…
I ordered the book (hadn’t arrived yet) and am interested in reading it, but after reading your posts, I may start saving for one. I have the talent I believe, but may lack the time and equipment.
If you have made one correctly without incident and according to Holme’s plans – congrats!
Thanks
My friend a tool and die maker and I have the book and video……
We spent 25 hours getting the plans together, The design is more than strong enough, also as the first one nears completion several details can be simplified. We are using purchased barrels and 4140 stock as really good M2 barrels are very hard to come by.