assertion of trademark, "jj's dual purpose magazine well" for the ar-15 lower receiver ...

one of the problems in utilizing the inherent utility of the ar-15 gun platform is that people have always considered the use of cartridges larger than the 5.56x45mm nato if not impossible, then so difficult as to preclude an easy utility.

it's the matter of shoehorning a cartridge into an ar-15 magazine, so as to have the magazine fit into the ar-15 magazine well.

i am in the process of finishing a project in which "jj's brit" ™ will be fitted into an ar-15 rifle, with no modifications to the upper and lower receiver, save for the use of a barrel extension promoted by harrison beane at www.ar15performance.com , which i have written about earlier.  there's been a bit of a problem, which harrison is addressing, but i am enthusiastic about the prospects of getting the whole thing to work.

as an expedient, we will be using pri's most excellent magazine for the 6.8mm remington spc, in order to house and feed the little "brit" in the completed rifle.  it is not any slander on the pri magazine to note that this is less than ideal, as the pri magazine was designed to house a cartridge with a case head of around .410 to .416's, and was never intended to reliably feed cartridges with a .473" case head, such as my little brit.

but, i've figured a way that with an absolute minimum of violence to the ar-15 platform and its inherent limitations due to size, that a magazine housing a .473 case head cartridge can be used in an ar-15 lower, while still allowing the use of magazines designed for the 5.56mm nato.  not at the same time, mind you, and not with the same upper, ... , we are talking about different cartridges and chamberings, what?

i've outline the process in the letter attached below.

for what it's worth, and given the sometimes futility of doing so in things involving firearm's manufacture, i assert intellectual property and trademark in the process described below.  it is not a lengthy process, just a matter of some relatively simply machining, but no one else has described it or done it, to the best of my knowledge.

i call the process and end product of same, as "jj's dual purpose magazine well,"™ for lack of any better term coming from my meager imagination.

the process.  (from a letter to a friend.)

 

____:

 

 

i am absolutely convinced, after futzing around with my little make shift magazine for .473" case headed cartridges, that it would be ridiculously easy to make one rather simple modification to the ar-15 lower, such that it could use magazines intended for the .223 family of cartridges, and also could use magazines that could use the .473" family of cartridges.   and, you could do so quite easily so that uppers to be used on such a lower would not need any modification at all.

one simply uses space the other doesn't need, and the space occupied by the larger does not affect the fit of the smaller.  pretty easy, actually.

i think you could do it with about .050" of "ledge."

mill the recess for the ar-15 magazine.  just as you do now.

mill the needed recess for the "jj's brit" magazine (i think a slight modified pri 6.8mm rem spc) would work just fine.)  simply mill this recess about .050 forward of the .376" case head magazine recess.  in essence, a couple little "wedges" along side the .223 magazine well.

the .376" magazines don't slop around lengthwise because both recesses terminate at a common surface.  the .376" magazine don't slop around side to side because of the slot at the back of the recess controls this, as does the material (what, around .050" as suggested) on the end corners of the .376" mag well, just behind the end of the .473" case head recess.

the .473" case head mags don't slop around end to end, because the little wedge at the back of the mag slips into the recess for the mag fabrication.  it doesn't slop around side to side, because it is confined by its own recess.

  

this would, obviously necessitate shortening the .473 case head cartridges a little bit for overall length, but, not so much as to make any damned difference.

it doesn't take much to get the .473" case-head-cartridges into the recess in the upper receiver, so that the bolt picks them up for feeding.  i've got the lugs on the bolt head in my .223 bushmaster just nicking the edge of the cases in the little ragtag magazine i am making with my dremel.  (i could have it done, except i am a bit leary about cutting off a feed lip.  laughing.) add just a bit of volume here, (for a little stouter magazine for the .473", feed lip wise) and even magpul, the chickens, could make a plastic mag with feed lips to hold the larger cartridge.  add a little more beef to the .223 family mags, and they, of course, suffer absolutely no issues with fit.

actually, if you started with a 6.8mm pri mag, instead of slaughtering an m-14 magazine (just a five rounder, no big loss, if you've ever tried to get one of the damn things out of an m1-a, trust me on this), there would be absolutely no issue at all shoehorning the feed lips into the recess in the upper receiver.   just machine some little wedges, and it's done.

imho.  (laughing a lot.)

simple as wiping ones rear end after defecation.

i thought it was impossible without making changes.  it is not.   i've done this with a dremel, a file, just dinking around.  magpul's engineers should be able to do it standing on their heads.

john

p.s.  i am going to assert a trademark on the process tonight, if i can open typepad.   for the fat lot of good that will do.

that's it.  hardly the stuff of genius.  but, i don't think anyone else has thought of it.  if they have, more power to them.  but, whoever thought of it first, it should work, and without too much "teething."

john jay @ 02.04.2013

 

Comments

[Rod]

JJ -
Interesting project as you continue to progress into the fielding and pre-commercial stages. Hope it goes well for your endeavor. Have you given much thought to the cost to your customers? Have done business with Brownell's since the early 90's, they sell parts and new stuff (they might be interested in your package)

I think this is a good thing you do with focusing on something less stressful than researching topics for the BLOG. It is certainly more fun for the old boy and protects him from becoming a dull one.

I have been busy fighting boredom by playing with some of my toys. Have added new furniture to my M4 and M-14. Changed out the magazine release to one that has release capabilities from either side and added a magwell grip to the M4 and replaced the bolt release and mag release with extended versions (easier to find without looking) for the M-14 (standard mods for military sniper versions - who am I to question success?). Have also received parts to complete legal conversion of Post-ban AK-47 (had already changed out much of the internals with US made parts) from the 10 round to 30 + magazines for my foster son's post-ban AK. While the AK is a well engineered system, I have been shot at too many times to lowere myself by owning one. More later, keep up the good work.