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January 31, 2014


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John, I suppose some of your readers aren't well informed on gun issues but this is all obvious.


If the case was severely overcharged, the bolt will be stuck "in battery" by either the pressure on the assembly, or because the pressure swaged the bolt into the barrel extension making it impossible to unlock (or both). However, the action still wants to cycle, and it has a hell of a lot more pressure than normal trying to cycle it, so when the bolt carrier tries to move rearward (while internally over pressurized with propellant gas) the cam pin rides the ramp in the carrier upward with considerable force. Since it can't turn to unlock, and since it can't go up to stay on the cam, the bolt carrier splits along its weakest axis (assisted by the aforementioned hellatious pressure inside), and proceeds from there to kinetically disassemble the upper receiver. On your plywood lower, it looks good, but I can't help but notice that you're a fellow who likes to work on guns and who owns a mortising machine, but doesn't own a milling machine. This is something that you must fix. Even a Bridgeport sized machine can be bought for less money than you've spent on perfecting JJ's Brit, and your lower project would have been a lot easier for you if you owned one. If you don't have room for a Bridgeport sized machine, Rong Fu or Grizzly both make a pretty decent little square column mill/drill machine that can be had for less than two grand. Used is cheaper still. You cannot be a proper tinkerer or insurrectionist gunsmith without a milling machine and hopefully a small lathe as well. Buy them and learn how to use them (or make friends with someone who will let you use theirs in exchange for beer or other valuable considerations).

john jay


it is?

apparently not to the people who ask me the question.


john jay

wide machinist:

an excellent analysis of the failure mechanism involved in the ar- coming apart.

it is pretty interesting how the bolt is still in the barrel extension, the barrel extension intact, and the firing pin in the bolt, ... , yet everything else in the upper is "distressed."

a fascinating picture.

now, as to "jj's brit," and the development cost thereof.

the "mule" used to develop the loads was equipped w/ a used barrel from a model 700 remington in 7mm remington magnum. that barrel was purchased from a friend for $30.00. (a gift, in other words, to let me retain my dignity. laughing.)

it cost an additional $50 or so in gas back and forth to a friend who is a retired gun smith.

cutting the barrel, rechambering and the like, cost me some possessions in barter. no money lost, and it cost me nothing to give something to a good friend.

the ar-15 in "jj's brit" cost me $165.00 for the barrel blank, purchased from harry mcgowen in montana. again, a trip to montana, and again some barter to cut the chamber, headspace the rifle, and cut the gas port and such.

the "go" and "no go" gauges were in the form of a master cartridge case sized in a 7mm-08 sizing and loading die with about .255" cut off them, by the same gun smith, and that cost me postage back to montana ... my friend footed the bill sending it to me.

the reamer for the cartridge was a .260 remington reamer with a collar placed on it, so that it would not enter the chamber too deeply. to establish the hole for the gas port a 6.8mm remington spc was disassembled, and the gas port hole measured, and we started a little smaller.

the brass for the cases was some once fired .243 winchester brass that i purchased 20 years ago, and have been lugging around and keeping underfoot all those years, with absolutely no use for it.

since then, i have used .30-06 (of all major manufacture, and some not so major), 8mm mauser, 7mm mauser, .308 winchester, .243 winchester and .22-250 savage as cases from which to make my "jj's brit." i have also used military brass, to include headstamps from "lc," "tw," "ut," and a host of foreign headstamps for 7.62mm nato.

oh, yes, i have used .280 remington, .280 ackley improved, .270 winchester, and .257 roberts to make cases.

almost all of it was scrounged, by me bending over and picking the stuff up.

the mortising machine was borrowed from a friend in town. i used a drill press to drill the holes, because some local people who own a bridgeport, and a "real" industrial sized one, were a bit nervous about "manufacturing" the lower for me.

so, i used a drill press unused in my dad's old shop for 40 years. needless to say, the bit "walked a bit," ... , my fault really.

if possible, next time i will use end mills, layup my assembly with hardened steel dowels to locate the assembly pin holes, and will not wait until the whole mess is laminated before i drill the holes for pins.

i cannot afford to buy the things you mention, though i fantasize about it. it would be nice.

but, i am a social security guy, with no assets, and more medical bills than i can ever hope to repay. five stents. quadruple bypass. courtesy the sisters of providence, in the great pacific northwest.

someplace else, without the tradition of the sister's medical charity, and i have been dead for nearly 25 years.

and, finally.

i wanted to see if someone could build a lower and an upper with rudimentary tools, rudimentary resources, using his native wit and materials at hand.

i think that i have proven rather handily that it can be done, with epoxy, drill press and ordinary bits, and enough patience and nerve to get the stuff square enough to work with files and some sweat.

i'd like to have the stuff to be proficient. but, i don't.

instead of proficiency, i have got by with some pluck, and patience to get things to "fit" by the use of simple hand tools.

i may not be "proper."

but, i "got 'er done," as the saying goes, and i haven't seen any proof that anyone else in the country was stupid enough to try it, and make it work.

john jay

p.s. you ain't seen nuthin yet. there is more in store.

insurgency cannot always be funded by soviet money, and intervention.

sometimes you just gotta make do.

you ever read "sometimes a great notion," by ken kesey. in my little impoverished area of n.e. oregon we have the proud tradition of the "gypo," who simply makes living on the short end of the stick.

i like to think i continue the tradition. so far i have far less than $350 or so in the innovation end of my guns, over the past two years.

i am kind of proud of that.

and, proud of my friends who helped me. very proud.

john jay

p.s. case forming.--
1.)depriming stem out of the sizing die, run a case through the die.
2.)cut the case to length.
3.)run the case through the die again, with the depriming stem and sizing ball in the sizing die.
4.)now the fun. run the case through a forster trimming lathe, with the outide neck turning tool on the end of the lathe. turn the handle, and take excess brass of the neck of the case, which is there because the brass on a case wall (of the parent case) is much thicker than the brass on the neck of the formed case.
5.)trim to length.
6.)repeat sizing and trimming, if case does not fit in the mule.

btw #1 -- if you put your back into it, and turn the crank vigorously, you can discernibly raise the temperature of the brass case. in a cold basement.

btw #2 -- the homemade sizer die, from rcbs in 7mm-08, sizes cases with the case shoulder at 1.300". dead nuts. the "mule" ejects cases fire formed in it, with the shoulder at 1.300". dead nuts. the ar-15 in "jj's brit," ejects cases with shoulders at 1.300". dead nuts.

the cost for all this? nothing in money, just work, and friendship.

i do not forget that.

scrounged. donated. bartered.

you think obama and minions are gonna come in and just take it? i don't.

john jay

p.s. oh, yeah, my brother nathan, since deceased, gave me the forster case trimming lathe for christmas, almost 45 years ago. he also gave me the rcbs rock chucker press, and my first set of loading dies.

he preferred dillons. i like my old rcbs equipment, and the loading blocks, and the powder measure designed to drive a person insane.

my brother steve owns my dad's old shop, and gave me permission to use the drill press.

and, for the record, i have $34.00 in the purchase of a new drill index, with 5/32nd, 1/4 and 3/8ths drill bits. and, about $10.00 for the epoxy. i bought the stainless steel plates from a junk shop in town for $2.00.

i have put countless hours of labor into this stuff, dressing steel with file and black sanders, and just doing things the hard way.

oddly enough, i got things done pretty quickly.

i am not a gun smith, and never will be. i am, however, a damned good tinkerer.

and, anyone with any gumption can do as well as me, with as little.

that is/was the point of the whole thing.

john jay

wide machinist:

one final comment, and then i'll get off my high horse.--

why do you think i report/write the way i do?

i could follow another approach, and do something without providing a narrative, and then figure out the "proper" way of doing it. then, after having removed all the error and warts, i could present a "clean" and "positive" narrative of how to do something, and try to look as "smart" doing it as possible.

instead i report the failures, and the steps backward, and the halt steps, and even the occasional bone headed mistake to which we are all prone, until the path is proven.

i do this on purpose.

i do this to encourage people to try things that are a bit unusual to them, and to consider doing some things a "little bit out of the box."

and, mostly i do it to show people that if they try, if they persevere, they can do so in the face of disappointment and set back.

in short, failure is only temporary.

and, to have faith that you can achieve a goal, even if you are not perfectly prepared, or equipped.

now, the next one of these things i will do the "right" way. with templates, and dowels, and so on and so forth.

but, every journey starts with the first step, and sometimes that step is a bit halt, and the next couples are too, and maybe some stumbles.

but, if you keep trying, you can get to where you want to be.

i'll tell you what. you do it the right way, you take photos, you write it up, and send it here, and i will publish it, with authorship and creation credited properly to you.

you make a receiver, and donate it to the public weal, and make it available to the insurrection, if one is fought.

and, show us all how to do it correctly.

and, for that you will have my gratitude, and my appreciation, and i will give you every ounce of credit you deserve.

john jay


Easy John, didn't mean to imply that your methods weren't proper or serviceable. Just meant that you'd find the going easier with better tools, nothing more. Your work thus far has been exemplary, and I enjoyed reading along as you did the work. For my contribution, I've been working on something a little non-AR. Everybody and their brothers have been working on AR lowers of one stripe or another, so I thought I'd dip my toes in the SMG puddle for my contributions. Right now I am about 90% done with the design and planning stage for a carbine chambered in 45 Auto. When I get it done and all the trouble shooting worked out, I will be offering them for sale to public at large as 80% kits. You finish the receiver, everything else is ready to bolt on. Takes M3 grease gun mags. I'll send you a link to the build thread over at the Weapons Guild when I get it rendered in actual metal. Right now all I have to show is CAD solids. Hopefully by early or mid-summer I will have the alpha rifle running and out for torture testing (I have a buddy who can destruct an anvil in a sand pile, so he does all my testing for me. If he can't break it, it can't be broke). I am right there beside you in that I believe that we must distribute our manufacturing base such that it cannot be attacked easily. Destroy one shop and the fifty others just spread that additional work load amongst themselves while another shop is found/built. The supply of arms never stops. That's the idea anyway. Until things go absolutely pear shaped, it's just a chance to make some money and help some DIY gunsmiths enlarge their skill sets and gun collections. Keep fighting the good fight, sir. There are plenty of us out here listening.

john jay

wide machinist:

thank you very much for this note.

i look forward eagerly to see your final build, on your project.

and, yes, your comments about spreading things around is very well taken, and very welcome.


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