5.56mm to 9mm Conversion

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  • crolfe1984

    Enthusiast
    Oct 21, 2007
    562
    Baltimore City, MD
    I currently have a DPMS 5.56/.223 complete rifle and I was wondering what to I have to do to the lower so I can use it with a 9mm upper? I'd love to take the AP4 to indoor ranges and, 9mm is cheap to shoot.

    I'd like to switch back and forth between 5.56mm and 9mm between shoots. Does anyone else do this here? I do not have much skill with gun smithing so I hope it is not a complicated process.
     

    h2u

    Village Idiot
    Jul 8, 2007
    6,694
    South County
    The process doesn't appear to be that complicated. Everything I know about this subject I've learned from JeepDriver so far.
    The parts list is as follows: Buffer, Mag Block (to fit in magazine well to fit the 9mm mags), Hammer, and 9mm bolt assembly. In addition you will need the 9mm upper. I think that should be all of the items needed. I have never taken my AR apart, so I don't know how difficult/easy it is to change out the above items. I do know that the mag block is just a compression fit. Easily removed. As I stated, I'm in the early stages of this as well so I'm sure someone will help with finishing anything I've left out. A lot of guys have probably forgotten more than I will ever know.....
     

    Norton

    NRA Endowment Member, Rifleman
    Staff member
    Admin
    Moderator
    May 22, 2005
    122,856
    I'll defer to JeepDriver when he gets over here, but from what I remember him saying the last time I asked him it seems that it's not necessarily "complicated" but is enough of a PITA that you want a dedicated lower for the 9mm.

    The hammer alone would seem to be a hassle to switch out because from what I remember you would have to drift those pins out every time.

    Like I said, I'll let JeepDriver give the definitive answer.
     

    Decoy

    Ultimate Member
    MDS Supporter
    Mar 2, 2007
    4,926
    Dystopia
    I have also put together a few 9m AR's if you have any questions.


    Going back and forth between 9mm to 5.56 requires changing the upper, mag block, buffer and hammer in most cases. Also remember that the 9mm upper uses a different bolt carrier assembly. It's much less of a hassle to purchase a second lower because the 9mm parts are not cheap.
     

    K-Romulus

    Suburban Commando
    Mar 15, 2007
    2,427
    NE MoCO
    Aside from the 9mm buffer, complete 9mm upper, 9mm mag block, and 9mm mags, the hammer is the biggest problem.

    Fortunately, you own the DPMS. I assume the parts kit is total DPMS from the factory?

    I ask because the DPMS 5.56 hammer is the only one of the major mfrs. that can be used with a 9mm bolt. Other mfrs. have a notch cut into the hammer face that snags on the 9mm bolt and jams the rifle into a big piece of pipe. DPMS, in contrast, just has one smooth polished surface.

    I have a STAG lower with DMPS parts kit that doubles as the 9mm on occasion. Switching back and forth with calibers is simply a matter of switching uppers and putting in the mag block; I run the 9mm buffer full time for 5.56. The mag block just locks into the mag well like a magazine.

    Let me know if you have more questions, but the best source of info would be the FAQ at the AR15.com sub-forum on pistol-caliber uppers.
     

    -Mil-Surp-Phreak-

    Ultimate Member
    Feb 26, 2007
    2,187
    Gaithersburg
    Here is my 9mm toy. It loves WWB bulk packs and once I get my Aimpoint thrown on top it will be even better.

    newpictures018js5.jpg
     

    Norton

    NRA Endowment Member, Rifleman
    Staff member
    Admin
    Moderator
    May 22, 2005
    122,856
    Dang, Mil-Surp.....that is way cool.

    Now you guys have got me thinking about building my lower up as a 9mm rather than the target gun I was going to build.......
     

    -Mil-Surp-Phreak-

    Ultimate Member
    Feb 26, 2007
    2,187
    Gaithersburg
    Ummm....got the RRA upper from CTAC but they are now defunct. Snagged their last one last year before he got out of the business for $460. I sold off the railed handguard and swapped in a M4 handguard and love it. I also used my "spare" AR lower and swapped in 9mm buffer and RRA 9mm hammer. I want to upgrade my magblock though, I have an ASA block that can take ribbed back UZI mags as well as Colt, Pro-Mag, and C-Products but it doesnt lock the bolt back on empty.
     

    Norton

    NRA Endowment Member, Rifleman
    Staff member
    Admin
    Moderator
    May 22, 2005
    122,856
    This is the set up Jeep is "holding my hand" through right now--but mine will have that funny looking flash hider that makes the rounds "seem" quieter...:D

    :envy:

    Me want....bad.
     

    h2u

    Village Idiot
    Jul 8, 2007
    6,694
    South County
    I was also more interested in the 45acp than in the 9mm. Jeep said Olympic Arms is the only one he knows of. He also said that there won't be a lot of aftermarket stuff for it.
    I decided to go with the 9mm because I can find several places to purchase any of the pieces I need. ANNNNND--most importantly to me--there are choices for suppressors for them.
     

    K-Romulus

    Suburban Commando
    Mar 15, 2007
    2,427
    NE MoCO
    I forgot to add:

    The Rock River Arms/Colt-type 9mm upper is the one that has the issue with the non-DPMS 5.56 hammer.

    An Olympic Arms 9mm upper can work with any type of hammer, but you are restricted to Sten(?) mags. The RRA-type upper can use Colt/C-Products and UZI mags, and maybe(?) Sten mags.
     

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