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.308 lower receiver magwell dimensions


toolmaker

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I am looking for the magwell dimensions of the most popular .308 ar platforms. I understand there are several types, and am preparing tooling to cut the magwells. The .223 magwells I am quoting appear to all be the same. I am hoping to provide a source for magwell broaching for those unwilling or unable to cough up 18k for broach tooling, and want to avoid the high cost of wire edm. If anyone can link the magwell dimensions, I would certainly appreciate it.

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This guy HERE has CNC'd a bunch of different guns. He has downloadable spec's for the AR-10 platform. This is the older style AR-10 that does NOT accept the DPMS LR-308 or KAC SR-25 magazines.

That being said, I still believe the DPMS/KAC style mags are the most popular. Especially since the release of the Magpul LR-20 PMAG.

There are a few others that use FN-FAL magazines and HK-G3 magazines. Not as popular, but much less expensive due to Euro-military surplus.

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As Robocop states, there are at least three different magwell types that I can think of, the original AR-10 which took proprietery Armalite mags, the DPMS/Knights pattern which "should" accept 308 P mags, and the ones set up for the FAL mags. the only one that I have ever seen a blueprint of is the AR-10. I don't think the companys that have developed the others are likely to share those dimensions. If you're going to tool up for something like this, the DPMS/knights is the way to go because that pattern has become the most popular, so much so that Armalte has released an AR-10 that accepts the DPMS/Knights/Magpul mags.

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I am currently tooled to broach the .223 magwells, and I have have tooling for one of the .308 magwells. To be very honest, I dont know much about the rifles, so I couldnt even say which style of the .308 magwells Im tooled up for. I know its not the ar-10, because that platform doesnt have a slot on both ends, one side is simply flat. Perhaps I can post the basic profile of the magwell, and someone can tell me which style it is. The customer who originally ordered the tooling backed out, and stuck me with many thousands of dollars in tooling. Since the tooling is mine, I am free to broach magwells for anyone who needs it done in the styles I have. I might as well make something back off of that nitemare.

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I presently have 3 .308 AR receivers on hand, all different manufacturers but all DPMS/Knights pattern. If it is of any help I can measure the length/width of each magwell and give you the dimensions, perhaps another member can give you the measurements for the AR 10 magwell so that you can ascertain which pattern your broach is for.

If you don't mind me asking, I'm thinking that aside from having the broach that passes through the rough hole to create the finished magwell, wouldn't you need some method to fixture the reciever in exactly the right position, reletive to the broach? And since so many of the receivers have different outside contours, it could be a headache as far as fixturing.

You know, as I'm writing this it occurs to me that this would only be of use for people with those 80% receivers, and I'm guessing that there aren't that many different forgings being made to sell to the general public, so maybe it could be a service that people would find useful, and that you might be able to provide. Maybe you could just offer forgings that already have the magwells broached?

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I really dont want to get into the business of selling receivers. I have all of the required tooling, and fixtures to broach the magwells. I get alot of rfq's for magwell broaching, and the biggest sticking point has always been the cost of broach tooling. Since I have already made the tooling, I simply want to provide the broaching service for the .223, and more common .308 magwell styles. I have provided edm services for the magwells on many occasions, but its costly... about 60 bucks per reciever. I can broach them in the 20.00 range depending on qty. The ar-10 magwell dimensions seem to be readily available. I may have to buy a each of the .308 stlyes, and run them through the cmm to get the required dimensions. I have found that alot of folks would like to make 80% recievers, but shy away from the expense of the tooling.

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certainly, the magwell machining, along with the thread for the receiver extension tube are the two most difficult/costly operations when trying to make your own lower receiever from a forging if your working on a manual mill. Good luck with it. I may be able to use your services in the future.

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