Jump to content
Brian Enos's Forums... Maku mozo!

How to go about prototyping/limited manufacturing custom ar lowers...

Recommended Posts

The only gunsmiths I personally know work on just about anything, but they don't manufacture or cnc, for the most part.  None have any suggestions on this so I thought I'd try here.


I want an AR lower that will take different magazines.  Some companies have teased it over the years, but no results.


I am confident in my design abilities (I mostly work in fusion360 and solidworks, but can use several others) I know ZERO about the business side of prototyping, and I don't have any relevant machining experience.


Is this a common thing in the ffl/manufacturing world?  Any help on how it works?  Is prototyping, when done to outside (Customer provided) plans, materials plus labor plus machine time?  Or do they also bid on projects?

I expect this will take at least 5 iterations, and possibly as many as X to a large power...  


Anyone have any recommendations as to which gunsmiths/companies/people I might approach about this?  




Link to post
Share on other sites

Talk to Johnny Lim at LimCat Customs.  Johnny has an extremely open and inventive mind.  Just take a look at some of his work.






SPARKS, NV 89431

Mon-Fri 10:00AM-5:00PM PST

(Excluding Holidays)

(775) - 856 - 2011



Link to post
Share on other sites

The one issue you may run into is making a lower requires a 07(i belive) manufactures FFL this limits you most likely to working with one of the smaller niche gun manufactures (like Limcat above)  that both have the proper license and the interest in taking on such a project. I would expect a project like this to be on the order of magnitude more expensive than a regular production lower from such a shop so expect each prototype to be several thousand dollars. 


So all that said is the idea to start a new company selling new lowers and or hole guns? If so you may be best off to patent your idea before you send drawings out to get manufactured by your future competition. then start a business and obtain the correct FFL and start shopping for a mill or a licensed partner. Dropping $20K to make a prototype that has not been patented along with as many work arounds as possible seems like a good way to end up with a big hole in your bank account.


If the idea is more make a cool gun for yourself then someone like Limcat makes more sense or you could have it machined to the same level as a 80% lower by an non FFL CNC shop and then doing the 20% yourself.



Link to post
Share on other sites

07 FFL for manufacturer is what you need if you're going to produce a functioning firearm.  Single biggest piece of advice is If you're going to partner with someone and there's a chance it's going to be a commercial venture, hammer out an agreement up front when everyone is friends and getting along.  If you don't, chances are very good you'll regret it, and possibly in a very big way.  How extensive the changes are is a factor in how you do this.  Used to be you could get unmachined AR lowers for dirt cheap.  Not sure that's the case any more.  You could possibly buy partially machined lowers or maybe even modify a stock lower.  Maybe take a look at some of the early AR9 configurations and see how those were done.  Another thing to consider for prototyping is 3D printing.  That's not going to hold up for actual use, but would be good for modeling and validation.  Given the number of people doing ARs, I'd think there has to be some open source software out there for CNC that could be modified to change certain design elements.  If that's the case, anyone familiar with the software should be able to do it pretty easily.  

Link to post
Share on other sites

If you don't have a lot of cash to spend, you'll probably have to partner with somebody with the machines and come up with a profit-sharing deal.   Prototyping and iterating and so on is time consuming, and time costs money in a CNC shop.   There are "Job shops", including some with FFLs that will machine parts to your drawings, but expect high charges for one-offs.  You can get them to quote off your drawings or solid models.


Every now and then I have people want me to prototype stuff for them (btw, I don't do ARs) and are surprised how much work and time is involved.  If you can start from something like a blank AR forging, that helps, but for a nevah-been-dun-befoah mag, I'm guessing that might not work.



Link to post
Share on other sites

I use 3D printers to prototype before machining the parts(not lowers). That would be the most economical way to do it. A Ender 3 can be bought for about $200. There is a learning curve but I was making good parts in no time. As far as machined parts you would be better off finding a shop that already makes lowers because they will already be set up for it and have the fixtures. Not to mention the 07 FFL. 

Link to post
Share on other sites

Not sure what design route you're going for, but I would start with a 80% or junky lower, drill some holes for retaining pins across the magwell to fit your magwell features/prototypes in. Design the prototypes in solidworks and find someone that can 3d print them out of polymer and ship them to you. Shouldn't be expensive and you avoid gunsmiths/FFLs.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...