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January 04, 2014


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I, for one, have been eagerly awaiting a video of a finished, functioning product.

You did mention earlier that now that you've run the gamut of mistakes and practical processes that you could make another in much less time.

Perhaps a new reciever to hold an AR-15 magazine?

john jay

right wing:

i have not abandoned the project. i am still contemplating building my own upper receiver from steel, ... , it is, after all, just a threaded tube with a slot for the magazine, a slot for the ejection of empties, and a couple of other extraneous things i would not replicate.

pretty simple for a machinists.

i am not a machinist.

i will have to enlist the aid of a machinist if i go that route.

other possibilities lay open. my ar-15 in "jj's brit" which is up and running, (and runs quite well), has a unique "fat" receiver that was built way over ar-15 specs. (nope, i don't know who made it, or why, i just noticed it one day in the "parts bin" at a local gun shop. in milton freewater, ... , go figure.)

it probably has enough metal at the bottom to accomodate the ar-10 magazine. i will check that. but, if i use that upper for this project, then i would be able to use it in all probability on my first ar-15 in "jj's brit." (makes no sense to sacrifice an operating gun for a "project" w/ an uncertain future, does it?)

and, i haven't the foggiest notion where i'd get another.

so, i'll complete the bottom. and, think on the upper receiver problem. this is not unusual w/ me, it took me many long months to cogitate my way through the ar-15 in "jj's brit." but, i finished it.

i am likely to finish this as well.

stay tuned.

john jay


I don't know if this will help, but you do not have to mill the upper to fit the whole AR10 magazine. That mag is built to hold a 2.8" cartridge, your JJ's are at most 2.5_" long. So in theory you could slice open a mag, carve 3/10" out of either the middle or the forward end then glue it back together (and wind your own mag spring and modify the follower). BUT if you did all that, you could leave 0.25+" more metal on the bottom of the upper. Yes, the cut would still have to be as high and as wide, to fit the cartridge.

Hmm, maybe glue/weld some metal straps to the outside for more strength?

What you are doing - the 2.5" AR15 - is what Stoner ought to have done back in the day. I'm beginning to wonder if the task couldn't be approached from the other end of things: take an AR10 and carve 0.3" out of it. Seriously, what advantage is the AR15 platform giving you here?

john jay


the issue is not with the length of the magazine, it is with the width of the thing. the ar-10 magazine is basically the same width as the bottom of the ar-15 rails.

if the upper were steel, i would just machine the upper and make room .... no biggie. but, i don't think the aluminum would stand up to the shock loads imposed by the bolt carrier group slamming in and out of battery.

the welding, then machining idea is pretty good, i think, but, i think the aluminum would simply warp too much. again, steel, ... , i would do it in a heart beat, just as you propose.

weld, machine, "fish scale/plate" it.

agreed. why stoner did not do this, e.g., make the ar-15 big enough to upgrade to the .308 is something of a mystery to me.

oddly enough, there is room in terms of length to do a .308 right now, even room to eject empties properly. just not enough width.

the advantage of the ar-15 stretching, as opposed to the ar-10 shrinking is strictly personal to me ... i can afford, barely, to scrape up enough over several months time to buy a component, and over time, enough components.

if we are talking ar-15 stuff.

ar-10 stuff is hellishly expensive, plus, it is not "government spec/mil spec," and interchangeability is an issue with ar-10 stuff. you cannot "mix & match" like you can w/ an ar-15.


p.s. as mentioned previously in these pages, the "answer" is the fn scar 17s, or the "heavy scar."

it would be easy to rebarrel/chamber one of those to "jj's brit," no problemo.

a lovely, elegant solution.

all it takes is $3,000 retail, out my way. needless to say, i don't have $3,000 laying around, or even lying around, for that matter.

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